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Ulmer, Alex; Kohlhammer, Jörn; Shulman, Haya

Towards Enhancing the Visual Analysis of Interdomain Routing

2017

Linsen, Lars (Ed.) et al.: IVAPP 2017. Proceedings : 8th International Conference on Information Visualization Theory and Applications (VISIGRAPP 2017 Volume 3). SciTePress, 2017, pp. 209-216

International Conference on Information Visualization Theory and Applications (IVAPP) <8, 2017, Porto, Portugal>

Interdomain routing with Border Gateway Protocol (BGP) plays a critical role in the Internet, determining paths that packets must traverse from a source to a destination. Due to its importance BGP also has a long history of prefix hijack attacks, whereby attackers cause the traffic to take incorrect routes, enabling traffic hijack, monitoring and modification by the attackers. Proposals for securing the protocol are adopted slowly or erroneous. Our goal is to create a novel visual analytics approach that facilitates easy and timely detection of misconfigurations and vulnerabilities both in BGP and in the secure proposals for BGP. This work initiates the analysis of the problem, the target users and state of the art approaches. We provide a comprehensive overview of the BGP threats and describe incidents that happened over the past years. The paper introduces two new user groups beside the network administrators, which should also be addressed in future approaches. It also contributes a survey about visual analysis of interdomain routing with BGP and secure proposals for BGP. The visualization approaches are rated and we derive seven key challenges that arise when following our roadmap for an enhanced visual analysis of interdomain routing.

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Ruppert, Tobias; Bannach, Andreas; Bernard, Jürgen; Lokanc, Martin; Kohlhammer, Jörn

Visual Access to Performance Indicators in the Mining Sector

2017

Kozlíková, Barbora (Ed.) et al.: Eurographics / IEEE VGTC Conference on Visualization (EuroVis) - Short Papers. Goslar: Eurographics Association, 2017, pp. 157-161

Eurographics / IEEE VGTC Conference on Visualization (EuroVis) <19, 2017, Barcelona, Spain>

We introduce a visualization system that provides visual interactive access to information relevant for decision making in the mining sector. The mining sector is one of the most important industries in developing countries, especially in Africa. Stakeholders like governments, investors, and the civil society play an important role in the growth of the mining sector. They are interested in information reviewing individual country performances towards mining. The Mining Investment and Governance Review (MInGov) dataset explicitly addresses this issue. However, the complex data structure introduces challenges for the intuitive and easy understanding of the information. Together with mining sector experts, we conducted a design study with the goal to provide visual interactive access to investment- and policy-related information. We report on a domain characterization of the MInGov dataset, its potential users, and their tasks. Based on this analysis, we design a visualization system that supports mining-related decision making. Finally, we evaluate the visualization system in a user workshop with domain experts.

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Ruppert, Tobias; Staab, Michael; Bannach, Andreas; Lücke-Tieke, Hendrik; Bernard, Jürgen; Kuijper, Arjan; Kohlhammer, Jörn

Visual Interactive Creation and Validation of Text Clustering Workflows to Explore Document Collections

2017

Wischgoll, Thomas (Ed.) et al.: Visualization and Data Analysis 2017. Springfield: IS&T, 2017. (Electronic Imaging), pp. 46-57

Visualization and Data Analysis (VDA) <2017, Burlingame, CA, USA>

The exploration of text document collections is a complex and cumbersome task. Clustering techniques can help to group documents based on their content for the generation of overviews. However, the underlying clustering workflows comprising preprocessing, feature selection, clustering algorithm selection and parameterization offer several degrees of freedom. Since no "best" clustering workflow exists, users have to evaluate clustering results based on the data and analysis tasks at hand. In our approach, we present an interactive system for the creation and validation of text clustering workflows with the goal to explore document collections. The system allows users to control every step of the text clustering workflow. First, users are supported in the feature selection process via feature selection metrics-based feature ranking and linguistic filtering (e.g., part-of-speech filtering). Second, users can choose between different clustering methods and their parameterizations. Third, the clustering results can be explored based on the cluster content (documents and relevant feature terms), and cluster quality measures. Fourth, the results of different clusterings can be compared, and frequent document subsets in clusters can be identified. We validate the usefulness of the system with a usage scenario describing how users can explore document collections in a visual and interactive way.

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Bernard, Jürgen; Dobermann, Eduard; Vögele, Anna; Krüger, Björn; Kohlhammer, Jörn; Fellner, Dieter W.

Visual-Interactive Semi-Supervised Labeling of Human Motion Capture Data

2017

Wischgoll, Thomas (Ed.) et al.: Visualization and Data Analysis 2017. Springfield: IS&T, 2017. (Electronic Imaging), pp. 34-45

Visualization and Data Analysis (VDA) <2017, Burlingame, CA, USA>

The characterization and abstraction of large multivariate time series data often poses challenges with respect to effectiveness or efficiency. Using the example of human motion capture data challenges exist in creating compact solutions that still reflect semantics and kinematics in a meaningful way. We present a visual-interactive approach for the semi-supervised labeling of human motion capture data. Users are enabled to assign labels to the data which can subsequently be used to represent the multivariate time series as sequences of motion classes. The approach combines multiple views supporting the user in the visual-interactive labeling process. Visual guidance concepts further ease the labeling process by propagating the results of supportive algorithmic models. The abstraction of motion capture data to sequences of event intervals allows overview and detail-on-demand visualizations even for large and heterogeneous data collections. The guided selection of candidate data for the extension and improvement of the labeling closes the feedback loop of the semi-supervised workflow. We demonstrate the effectiveness and the efficiency of the approach in two usage scenarios, taking visual-interactive learning and human motion synthesis as examples.

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Bernard, Jürgen; Ritter, Christian; Sessler, David; Zeppelzauer, Matthias; Kohlhammer, Jörn; Fellner, Dieter W.

Visual-Interactive Similarity Search for Complex Objects by Example of Soccer Player Analysis

2017

Linsen, Lars (Ed.) et al.: IVAPP 2017. Proceedings : 8th International Conference on Information Visualization Theory and Applications (VISIGRAPP 2017 Volume 3). SciTePress, 2017, pp. 75-87

International Conference on Information Visualization Theory and Applications (IVAPP) <8, 2017, Porto, Portugal>

The definition of similarity is a key prerequisite when analyzing complex data types in data mining, information retrieval, or machine learning. However, the meaningful definition is often hampered by the complexity of data objects and particularly by different notions of subjective similarity latent in targeted user groups. Taking the example of soccer players, we present a visual-interactive system that learns users' mental models of similarity. In a visual-interactive interface, users are able to label pairs of soccer players with respect to their subjective notion of similarity. Our proposed similarity model automatically learns the respective concept of similarity using an active learning strategy. A visual-interactive retrieval technique is provided to validate the model and to execute downstream retrieval tasks for soccer player analysis. The applicability of the approach is demonstrated in different evaluation strategies, including usage scenarions and cross-validation tests.

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Kohlhammer, Jörn; Proff, Dirk U.; Wiener, Andreas

Der Markt für Visual Business Analytics

2016

Gluchowski, Peter (Ed.) et al.: Analytische Informationssysteme : Business Intelligence-Technologien und -Anwendungen. Springer Gabler, 2016, pp. 303-323

Visualisierung wird im Bereich Business Intelligence (BI) und Business Analytics immer wichtiger. Heutige BI-Software, gerade im Bereich der Self-Service-BI, wird von den Anwendern ohne ein interaktives Benutzerinterface, das ihnen verschiedene Visualisierungsmöglichkeiten bietet, nicht mehr akzeptiert. Dennoch muss Unternehmen und Anwendern noch besser dargelegt werden, wie sie von solchen Visualisierungslösungen am Ende tatsächlich profitieren können. Dieser genaueren Betrachtung der Vorteile widmet sich der Bereich Visual Business Analytics (VBA), der drei Teilthemen umfasst: Information Design (ID), Visual Business Intelligence (VBI) und Visual Analytics (VA). Dieser Beitrag soll anhand illustrativer Beispiele in diese Teilthemen einführen.

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Nazemi, Kawa; Steiger, Martin; Burkhardt, Dirk; Kohlhammer, Jörn

Information Visualization and Policy Modeling

2016

Khosrow-Pour, Mehdi (Editor-in-Chief): Big Data: Concepts, Methodologies, Tools, and Applications : Volume 1. Hershey, Pennsylvania: IGI Global, 2016, pp. 139-180

Policy design requires the investigation of various data in several design steps for making the right decisions, validating, or monitoring the political environment. The increasing amount of data is challenging for the stakeholders in this domain. One promising way to access the "big data" is by abstracted visual patterns and pictures, as proposed by information visualization. This chapter introduces the main idea of information visualization in policy modeling. First abstracted steps of policy design will be introduced that enables the identification of information visualization need in the entire policy lifecycle. Thereafter the foundations of information visualization will be introduced based on an established reference model. We aim to amplify the incorporation of information visualization in the entire policy design process. Therefore the aspects of data and human interaction will be introduced too. The foundation leads to description of a conceptual design for social data visualization, whereas the aspect of semantics plays an important role.

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Kohlhammer, Jörn

Informationsvisualisierung und Visual Analytics

2016

Klein, Andreas (Ed.) et al.: Visualisierung von Managementberichten. Berlin; Freiburg i. Br.: Haufe, 2016. (Der Controlling-Berater 44), pp. 81-98

Die Visualisierung von Geschäftsdaten und großen Datenmengen für die Entscheidungsfindung nimmt einen immer wichtigeren Stellenwert ein. Für die effektive Nutzung heutiger Tools ist ein Grundverständnis der Visualisierung nötig. Das Wissen über die menschliche Wahrnehmung erlaubt es, grundlegende Herangehensweisen zum Aufbau effektiver Visualisierungen zu formulieren und zu nutzen. Die richtige Informationsvisualisierung von Daten für die richtigen Nutzer und Aufgaben beschleunigt das Erkennen und Verstehen dieser Daten immens. Massive Datenmengen benötigen erweiterte Ansätze zur Integration von Visualisierung und automatischen Datenverarbeitung. Diese Ansätze bezeichnen wir als Visual Analytics. Der Prozess des User-Centered Design stellt sicher, dass der Nutzer während Planung und Entwicklung von Visualisierungen im Zentrum des Interesses steht. Der Beitrag gibt einen Überblick über Grundlagen der Visualisierung auch für große Datenmengen. Zudem hebt erdie wichtige Beachtung der Benutzer bei der Erstellung jeglicher Visualisierung hervor.

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Kohlhammer, Jörn

Informationsvisualisierung und Visual Analytics

2016

Schneider, Christian (Ed.) et al.: Managementberichte gekonnt visualisieren : Standards und Design-Grundsätze für ein aussagekräftiges Reporting. Berlin; Freiburg i. Br.: Haufe, 2016, pp. 81-98

Die Visualisierung von Geschäftsdaten und großen Datenmengen für die Entscheidungsfindung nimmt einen immer wichtigeren Stellenwert ein. Für die effektive Nutzung heutiger Tools ist ein Grundverständnis der Visualisierung nötig. Das Wissen über die menschliche Wahrnehmung erlaubt es, grundlegende Herangehensweisen zum Aufbau effektiver Visualisierungen zu formulieren und zu nutzen. Die richtige Informationsvisualisierung von Daten für die richtigen Nutzer und Aufgaben beschleunigt das Erkennen und Verstehen dieser Daten immens. Massive Datenmengen benötigen erweiterte Ansätze zur Integration von Visualisierung und automatischen Datenverarbeitung. Diese Ansätze bezeichnen wir als Visual Analytics. Der Prozess des User-Centered Design stellt sicher, dass der Nutzer während Planung und Entwicklung von Visualisierungen im Zentrum des Interesses steht. Der Beitrag gibt einen Überblick über Grundlagen der Visualisierung auch für große Datenmengen. Zudem hebt er die wichtige Beachtung der Benutzer bei der Erstellung jeglicher Visualisierung hervor.

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Ruddle, Roy A.; Bernard, Jürgen; May, Thorsten; Lücke-Tieke, Hendrik; Kohlhammer, Jörn

Methods and a Research Agenda for the Evaluation of Event Sequence Visualization Techniques

2016

IEEE Computer Society Visualization and Graphics Technical Committee (VGTC): IEEE VIS 2016 Workshop on Temporal and Sequential Event Analysis : The Event Event: Temporal & Sequential Event Analysis [online]. [cited 01 February 2017] Available from: [http://eventevent.github.io/], 2016, 4 p.

IEEE VIS 2016 Workshop on Temporal & Sequential Event Analysis <2016, Baltimore, USA>

The present paper asks how can visualization help data scientists make sense of event sequences, and makes three main contributions. The first is a research agenda, which we divide into methods for presentation, interaction & computation, and scale-up. Second, we introduce the concept of Event Maps to help with scale-up, and illustrate coarse-, medium- and fine-grained Event Maps with electronic health record (EHR) data for prostate cancer. Third, in an experiment we investigated participants' ability to judge the similarity of event sequences. Contrary to previous research into categorical data, color and shape were better than position for encoding event type. However, even with simple sequences (5 events of 3 types in the target sequence), participants only got 88% correct despite averaging 7.4 seconds to respond. This indicates that simple visualization techniques are not effective.

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Ruppert, Tobias; Bannach, Andreas; Bernard, Jürgen; Lücke-Tieke, Hendrik; Ulmer, Alex; Kohlhammer, Jörn

Supporting Collaborative Political Decision Making - An Interactive Policy Process Visualization System

2016

Kerren, Andreas (Ed.) et al.: Proceedings of the 9th International Symposium on Visual Information Communication and Interaction : INCI 2016 [online]. ACM, 2016, 8 p.

International Symposium on Visual Information Communication and Interaction (VINCI 2016) < 9, 2016, Dallas, Texas>

The process of political decision making is often complex and tedious. The policy process consists of multiple steps, most of them are highly iterative. In addition, different stakeholder groups are involved in political decision making and contribute to the process. A series of textual documents accompanies the process. Examples are official documents, discussions, scientific reports, external reviews, newspaper articles, or economic white papers. Experts from the politi- cal domain report that this plethora of textual documents often exceeds their ability to keep track of the entire policy process. We present PolicyLine, a visualization system that supports different stakeholder groups in overview-and-detail tasks for large sets of textual documents in the political decision making process. In a longitudinal design study conducted together with domain experts in political decision making, we identfied missing analytical functionality on the basis of a problem and domain characterization. In an iterative design phase, we created PolicyLine in close collaboration with the domain experts. Finally, we present the results of three evaluation rounds, and reect on our collaborative visualization system.

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Sessler, David; Spott, Martin; Nauck, Detlef; Harmer, William; Kohlhammer, Jörn; Bernard, Jürgen

Towards Combining Attribute-Based and Time Series-Based Visual Querying

2016

Isenberg, Tobias (Ed.) et al.: EuroVis 2016. Eurographics / IEEE Symposium on Visualization 2016: Posters. Goslar: Eurographics Association, 2016, pp. 73-75

Eurographics Conference on Visualization (EuroVis) <18, 2016, Groningen, The Netherlands>

We present a concept for the visual-interactive definition of meaningful subsets in data sets comprising multivariate attributes and time series data. Based on a generalization of requirements of a real-world user group, we propose a three-stage approach, combining visual-interactive querying, query filter analysis, and result exploration. The approach includes several design parameters that can easily be adapted in future design studies for alternative applications.

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Huynh, Ngoc Anh; Ng, Wee Keong; Ulmer, Alex; Kohlhammer, Jörn

Uncovering Periodic Network Signals of Cyber Attacks

2016

Best, Daniel M. (Ed.) et al.: VizSec 2016 : 2016 IEEE Symposium on Visualization for Cyber Security. The Institute of Electrical and Electronics Engineers (IEEE), 2016, 8 p.

IEEE Symposium on Visualization for Cyber Security (VizSec) <2016, Baltimore, MD, USA>

This paper addresses the problem of detecting the presence of malware that leave periodic traces in network traffic. This characteristic behavior of malware was found to be surprisingly prevalent in a parallel study. To this end, we propose a visual analytics solution that supports both automatic detection and manual inspection of periodic signals hidden in network traffic. The detected periodic signals are visually verified in an overview using a circular graph and two stacked histograms as well as in detail using deep packet inspection. Our approach offers the capability to detect complex periodic patterns, but avoids the unverifiability issue often encountered in related work. The periodicity assumption imposed on malware behavior is a relatively weak assumption, but initial evaluations with a simulated scenario as well as a publicly available network capture demonstrate its applicability.

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Bernard, Jürgen; Sessler, David; Steiger, Martin; Spott, Martin; Kohlhammer, Jörn

Visual-Interactive Exploration of Relations Between Time-Oriented Data and Multivariate Data

2016

Andrienko, Natalia (Ed.) et al.: EuroVA 2016 : EuroVis Workshop on Visual Analytics. Goslar: Eurographics Association, 2016, pp. 49-53

International EuroVis Workshop on Visual Analytics (EuroVA) <7, 2016, Groningen, The Netherlands>

The analysis of large, multivariate data sets is challenging, especially when some of these data objects are timeoriented. Exploring relationships between multivariate and temporal information, e.g., to identify patterns that support decision making is an important industrial analysis task. The target group of this design study are data analysts aiming at detecting fault patterns in a telecommunications network in order to spend maintenance budget more effectively. We present a visual analytics tool that provides overviews of multivariate data sets and associated time series. Users can select data subsets of interest in both attribute data and clustered time series data. Linked views consequently support the identification of relations between the two spaces. To ensure usefulness, the tool was designed in an iterative way, based on a careful characterization of the data, users, and tasks. A usage scenario demonstrates the applicability of the approach.

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Bernard, Jürgen; Dobermann, Eduard; Bögl, Markus; Röhlig, Martin; Vögele, Anna; Kohlhammer, Jörn

Visual-Interactive Segmentation of Multivariate Time Series

2016

Andrienko, Natalia (Ed.) et al.: EuroVA 2016 : EuroVis Workshop on Visual Analytics. Goslar: Eurographics Association, 2016, p. 31-35

International EuroVis Workshop on Visual Analytics (EuroVA) <7, 2016, Groningen, The Netherlands>

Choosing appropriate time series segmentation algorithms and relevant parameter values is a challenging problem. In order to choose meaningful candidates it is important that different segmentation results are comparable. We propose a Visual Analytics (VA) approach to address these challenges in the scope of human motion capture data, a special type of multivariate time series data. In our prototype, users can interactively select from a rich set of segmentation algorithm candidates. In an overview visualization, the results of these segmentations can be compared and adjusted with regard to visualizations of raw data. A similarity-preserving colormap further facilitates visual comparison and labeling of segments. We present our prototype and demonstrate how it can ease the choice of winning candidates from a set of results for the segmentation of human motion capture data.

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Bernard, Jürgen; Steiger, Martin; Mittelstädt, Sebastian; Thum, Simon; Keim, Daniel A.; Kohlhammer, Jörn

A Survey and Task-Based Quality Assessment of Static 2D Colormaps

2015

Kao, David L. (Ed.) et al.: Visualization and Data Analysis 2015. SPIE Press, 2015. (Proceedings of SPIE 9397), pp. 93970M-1 - 93970M-16

IS&T/SPIE Conference on Visualization and Data Analysis (VDA) <15, 2015, San Francisco, CA, USA>

Color is one of the most important visual variables since it can be combined with any other visual mapping to encode information without using additional space on the display. Encoding one or two dimensions with color is widely explored and discussed in the field. Also mapping multi-dimensional data to color is applied in a vast number of applications, either to indicate similar, or to discriminate between different elements or (multi-dimensional) structures on the screen. A variety of 2D colormaps exists in literature, covering a large variance with respect to different perceptual aspects. Many of the colormaps have a different perspective on the underlying data structure as a consequence of the various analysis tasks that exist for multivariate data. Thus, a large design space for 2D colormaps exists which makes the development and use of 2D colormaps cumbersome. According to our literature research, 2D colormaps have not been subject of in-depth quality assessment. Therefore, we present a survey of static 2D colormaps as applied for information visualization and related fields. In addition, we map seven devised quality assessment measures for 2D colormaps to seven relevant tasks for multivariate data analysis. Finally, we present the quality assessment results of the 2D colormaps with respect to the seven analysis tasks, and contribute guidelines about which colormaps to select or create for each analysis task.

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Bernard, Jürgen; Sessler, David; Bannach, Andreas; May, Thorsten; Kohlhammer, Jörn

A Visual Active Learning System for the Assessment of Patient Well-Being in Prostate Cancer Research

2015

Gschwandtner, Theresia (Conference Chair) et al.: Proceedings of the 2015 Workshop on Visual Analytics in Healthcare. New York: ACM, 2015, Art. 1, 8 p.

Workshop in Visual Analytics in Healthcare (VAHC) <2015, Chicago, IL, USA>

The assessment of patient well-being is highly relevant for the early detection of diseases, for assessing the risks of therapies, or for evaluating therapy outcomes. The knowledge to assess a patient's well-being is actually tacit knowledge and thus, can only be used by the physicians themselves. The rationale of this research approach is to use visual interfaces to capture the mental models of experts and make them available more explicitly. We present a visual active learning system that enables physicians to label the well-being state of patient histories su ering prostate cancer. The labeled instances are iteratively learned in an active learning approach. In addition, the system provides models and visual interfaces for a) estimating the number of patients needed for learning, b) suggesting meaningful learning candidates and c) visual feedback on test candidates. We present the results of two evaluation strategies that prove the validity of the applied model. In a representative real-world use case, we learned the feedback of physicians on a data collection of more than 16.000 prostate cancer histories.

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Bernard, Jürgen; Sessler, David; May, Thorsten; Schlomm, Thorsten; Pehrke, Dirk; Kohlhammer, Jörn

A Visual-Interactive System for Prostate Cancer Cohort Analysis

2015

IEEE Computer Graphics and Applications, Vol.35 (2015), 3, pp. 44-55

Data-centered research is becoming increasingly important in prostate cancer research, where a long-term goal is a sound prognosis prior to surgery. The proposed visual-interactive system, developed in close collaboration with medical researchers, helps physicians efficiently and effectively visualize single and multiple patient histories at a glance.

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Gschwandtner, Theresia; Schumann, Heidrun; Bernard, Jürgen; May, Thorsten; Bögl, Markus; Miksch, Silvia; Kohlhammer, Jörn; Röhlig, Martin; Alsallakh, Bilal

Enhancing Time Series Segmentation and Labeling Through the Knowledge Generation Model: Poster presented at the Eurographics Conference on Visualization (EuroVis)

2015

2015

Eurographics Conference on Visualization (EuroVis) <17, 2015, Cagliari, Sardinia, Italy>

Segmentation and labeling of different activities in multivariate time series data is an important task in many domains. There is a multitude of automatic segmentation and labeling methods available, which are designed to handle different situations. These methods can be used with multiple parametrizations, which leads to an overwhelming amount of options to choose from. To this end, we present a conceptual design of a Visual Analytics framework (1) to select appropriate segmentation and labeling methods with appropriate parametrizations, (2) to analyze the (multiple) results, (3) to understand different kinds and origins of uncertainties in these results, and (4) to reason which methods and which parametrizations yield stable results and fine-tune these configurations if necessary.

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Steiger, Martin; Bernard, Jürgen; Thum, Simon; Mittelstädt, Sebastian; Hutter, Marco; Keim, Daniel A.; Kohlhammer, Jörn

Explorative Analysis of 2D Color Maps

2015

Gavrilova, Marina L. (Ed.) et al.: WSCG 2015. Full Papers Proceedings : 23rd International Conference in Central Europe on Computer Graphics, Visualization and Computer Vision. [cited 16 October 2015] Available from http://wscg.zcu.cz/DL/wscg DL.htm: University of West Bohemia, 2015, pp. 151-160

International Conference in Central Europe on Computer Graphics, Visualization and Computer Vision (WSCG) <23, 2015, Plzen, Czech Republic>

Color is one of the most important visual variables in information visualization. In many cases, two-dimensional information can be color-coded based on a 2D color map. A variety of color maps as well as a number of quality criteria for the use of color have been presented. The choice of the best color map depends on the analytical task users intend to perform and the design space in choosing an appropriate 2D color map is large. In this paper, we present the ColorMap-Explorer, a visual-interactive system that helps users in selecting the most appropriate 2D color map for their particular use case. ColorMap-Explorer also provides a library of many color map implementations that have been proposed in the scientific literature. To analyze their usefulness for different tasks, ColorMap-Explorer provides use case scenarios to allow users to obtain qualitative feedback. In addition, quantitative metrics are provided on a global (i.e. per color map) and local (i.e. per point) scale. ColorMap-Explorer enables users to explore the strengths and weaknesses of existing as well as user-provided color maps to find the best fit for their task. Any color map can be exported to be reused in other visualization tools. The code is published as open source software, so that the visualization community can use both the color map library and the ColorMap-Explorer tool. This also allows users to contribute new implementations.

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Burkhardt, Dirk; Nazemi, Kawa; Ginters, Egils; Aizstrauts, Artis; Kohlhammer, Jörn

Explorative Visualization of Impact Analysis for Policy Modeling by Bonding Open Government and Simulation Data

2015

Yamamoto, Sakae (Ed.): Human Interface and the Management of Information. Proceedings Part I : Information and Knowledge Design. Springer International Publishing, 2015. (Lecture Notes in Computer Science (LNCS) 9172), pp. 34-45

International Conference on Human Interface and the Management of Information (HIMI) <2015, Los Angeles, CA, USA>

Problem identification and solution finding are major challenges in policy modeling. Statistical indicator-data build the foundation for most of the required analysis work. In particular finding effective and efficient policies that solve an existing political problem is critical, since the forecast validation of the effectiveness is quite difficult. Simulation technologies can help to identify optimal policies for solutions, but nowadays many of such simulators are standalone technologies. In this paper we introduce a new visualization approach to enable the coupling of statistical indicator data from Open Government Data sources with simulators and especially simulation result data with the goal to provide an enhanced impact analysis for political analysts and decision makers. This allows, amongst others a more intuitive and effective way of solution finding.

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Burkhardt, Dirk; Nazemi, Kawa; Zilke, Jan Ruben; Kohlhammer, Jörn; Kuijper, Arjan

Fundamental Aspects for E-Government

2015

Information Resources Management Association (IRMA): Standards and Standardization : Concepts, Methodologies, Tools, and Applications (3 Volumes). IGI Global, 2015, pp. 52-68

The upcoming initiatives using ICT in the government process should strengthen the benefit of e-government in most countries. Since e-government among other e-related terms is a widely (interpreted) term, it is sometimes challenging to understand the objective and goals of an initiative. Therefore, in this chapter, the authors introduce and explain most e-government related terms. Even more, they outline some interesting initiatives and implementations to explain the benefits of using ICT in the government domain. Concrete activities are aligned to the terms to explain their practical use in a better way. The authors conclude with several challenges that arise when thinking of the implementation of e-government services. Overall, this chapter should give a good overall view of e-government and the related issues.

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Encarnação, L. Miguel; Chuang, Yung-Yu; Stork, André; Kasik, Dave; Rhyne, Theresa-Marie; Avila, Lisa S.; Kohlhammer, Jörn; LaViola, Joseph J.; Tory, Melanie; Dill, John; Domik, Gitta; Owen, G. Scott; Wong, Pak Chung

Future Directions in Computer Graphics and Visualization: From CG&A's Editorial Board: Letter from the Editor

2015

IEEE Computer Graphics and Applications, Vol.35 (2015), 1, pp. 20-32

With many new members joining the CG&A editorial board over the past year, and with a renewed commitment to not only document the state of the art in computer graphics research and applications but to anticipate and where possible foster future areas of scientific discourse and industrial practice, CG&A asked its editorial and advisory council members about where they see their fields of expertise going. The answers compiled here aren't meant to be all encompassing or deterministic when it comes to the opportunities computer graphics and interactive visualization hold for the future. Instead, the goal is to give a more in-depth introduction of members of the editorial board to the CG&A readership and encourage cross-disciplinary discourse toward approaching, complementing, or disputing the visions laid out in this compilation. Here's what the CG&A editorial and advisory council members had to say.

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Burkhardt, Dirk; Nazemi, Kawa; Kohlhammer, Jörn

Policy Modeling Methodologies

2015

Information Resources Management Association: Public Affairs and Administration : Concepts, Methodologies, Tools, and Applications (4 Volumes). Hershey, Pennsylvania: IGI Global, 2015, pp. 512-524

The process to develop sustainable public policies is done by public authorities ensuring the involvement of all stakeholders. ICT is rarely included in most of the today's applied policymaking processes. Other process definitions with a focus on ICT inclusion in policy modeling still exist, but they are not well defined. This chapter gives an overview of the existing policy modeling process types and explains their major foci and how they consider ICT and the practical process in public authorities. Afterwards, based on these descriptions, the general requirements on a new ICT-oriented policy modeling process that allows the inclusion of ICT into a valid and useful process for public authorities is given.

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Nazemi, Kawa; Burkhardt, Dirk; Ginters, Egils; Kohlhammer, Jörn

Semantics Visualization - Definition, Approaches and Challenges

2015

Procedia Computer Science [online], Vol.75 (2015), pp. 75-83

2015 International Conference on Virtual and Augmented Reality in Education (VARE) <3, 2015, Monterrey City, Mexico>

The visualization of the simulation results must be done in conformity with beneficiaries perception and professional domain understanding. It means that right data must be identified before. Semantic technologies provide new ways for accessing data and acquiring knowledge. The underlying structures allow finding information easier, gathering meanings and associations of the data entities and associating the data to users' knowledge. Even though the focus of the research in this area is more to provide ''machine readable'' data, human-centered systems benefit from the technologies too. Especially graphical representations of the semantically structured data play a key-role in today's research. The meaningful relations of data entities and the meaningful and labeled clustering of data in form of semantic concepts enable new ways to visualize data. With these new ways, various challenges are related with deploying semantics visualizations beyond analytical search and simulation. The goal is to give a common understanding of the term semantics as it is used in semantic web. This paper dealt with the general idea of semantics visualization. First a short introduction to semantic formalisms is given followed by a general definition. Subsequently approaches and techniques of existing semantics visualizations are presented, where-as a new classification is introduced to describe the techniques. The article concludes with future challenges in semantics visualization focusing on users, data and tasks.

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Steiger, Martin; Fellner, Dieter W. (Betreuer); Kohlhammer, Jörn (Betreuer)

Supporting Management of Sensor Networks through Interactive Visual Analysis

2015

Darmstadt, TU, Diss., 2015

With the increasing capabilities of measurement devices and computing machines, the amount of recorded data grows rapidly. It is so high that manual processing is no longer feasible. The Visual Analytics approach is powerful because it combines the strengths of human recognition and vision system with today's computing power. Different, but strongly linked visualizations and views provide unique perspectives on the same data elements. The views are linked using position on the screen as well as color, which also plays a secondary role in indicating the degree of similarity. This enables the human recognition system to identify trends and anomalies in a network of measurement readings. As a result, the data analyst has the ability to approach more complex questions such as: are there anomalies in the measurement records? What does the network usually look like? In this work we propose a collection of Visual Analytics approaches to support the user in exploratory search and related tasks in graph data sets. One aspect is graph navigation, where we use the information of existing labels to support the user in analyzing with this data set. Another consideration is the preservation of the user's mental map, which is supported by smooth transitions between individual keyframes. The later chapters focus on sensor networks, a type of graph data that additionally contains time series data on a per-node basis; this adds an extra dimension of complexity to the problem space. This thesis contributes several techniques to the scientific community in different domains and we summarize them as follows. We begin with an approach for network exploration. This forms the basis for subsequent contributions, as it to supports user in the orientation and the navigation in any kind of network structure. This is achieved by providing a showing only a small subset of the data (in other words: a local graph view). The user expresses interest in a certain area by selecting one of more focus nodes that define the visible subgraph. Visual cues in the form of pointing arrows indicate other areas of the graph that could be relevant for the user. Based on this network exploration paradigm, we present a combination of different techniques that stabilize the layout of such local graph views by reducing acting forces. As a result, the movement of nodes in the node-link diagram is reduced, which reduces the mental effort to track changes on the screen. However, up to this point the approach suffers from one of the most prominent shortcomings of force-directed graph layouts. Little changes in the initial setup, force parameters, or graph topology changes have a strong impact on the visual representation of the drawing. When the user explores the network, the set of visible nodes continuously changes and therefore the layout will look different when an area of the graph is visited a second time. This makes it difficult to identify differences or recognize different drawing as equal in terms of topology. We contribute an approach for the deterministic generation of layouts based on pre-computed layout patches that are stitched at runtime. This ensures that even force-directed layouts are deterministic, allowing the analyst to recognize previvously explored areas of the graph. In the next step, we apply these rather general purpose concepts from theory in practical applications. One of the most important network category is that of sensor networks, a type of graph data structure where every node is annotated with a time series. Such networks exist in the form of electric grids and other supply networks. In the wake of distributed and localized energy generation, the analysis of these networks becomes more and more important. We present and discuss a multi-view and multi-perspective environment for network analysis of sensor networks that integrates different data sources. It is then extended into a visualization environment that enables the analyst to track the automated analysis of the processing pipeline of an expert system. As a result, the user can verify the correctness of the system and intervene where necessary. One key issue with expert systems, which typically operate on manually written rules, is that they can deal with explicit statements. They cannot grasp terms such as "uncommon" or "anomalous". Unfortunately, this is often what the domain experts are looking for. We therefore modify and extend the system into an integrated analysis system for the detection of similar patterns in space and in different granularities of time. Its purpose is to obtain an overview of a large system and to identify hot spots and other anomalies. The idea here is to use similar colors to indicate similar patterns in the network. For that, it is vital to be able to rely on the mapping of time series patterns to color. The Colormap-Explorer supports the analysis and comparison of different implementations of 2D color maps to find the best fit for the task. As soon as the domain expert has identified problems in the networks, he or she might want to take countermeasures to improve the network stability. We present an approach that integrates simulation in the process to perform "What-If" analysis based on an underlying simulation framework. Subsequent runs can be compared to quickly identify differences and discover the effect of changes in the network. The approaches that are presented can be utilized in a large variety of applications and application domains. This enables the domain expert to navigate and explore networks, find key elements such as bridges, and detect spurious trends early.

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Ramfos, Antonis; Kiousi, Akrivi; Kokkonidis, Miltiadis; Leclercq, Christophe; Mekkaoui, David; Sattonnay, Maxime; Maragoudakis, Manolis; Androutsopoulou, Aggeliki; Charalabidis, Yannis; Kohlhammer, Jörn; Ruppert, Tobias; Lücke-Tieke, Hendrik; Dimakopoulos, Nikos; Kallipolitis, Leonidas; Nikodem, Pavel; Madlenak, Tomas; Mureddu, Francesco; Pyrenis, Demetrios; Protonotarios, Matthew; Ipektsidis, Charalampos

The "EU Community" Project - Coupling the Power of Data with Community Expertise

2015

Askounis, Dimitros (Ed.) et al.: EEPM 2015 Enabling Effective Policy Making : Proceedings of the Workshop on Enabling Effective Policy Making 2015 -. CEUR-Workshop Proceedings, 2015. (CEUR Workshop Proceedings 1553), 9 p.

Workshop on Enabling Effective Policy Making (EEPM) <2015, Thessaloniki, Greece>

The EU Community project seeks to promote, facilitate, and ultimately exploit the synergy of a cutting-edge intelligent collaboration platform with a community of institutional actors, stakeholders, scientists, consultants, media analysts and other individuals that can make valuable contributions to EU policy debates. Its ultimate goal is to effectuate a transformation in the modus operandi of EU politics and move closer to achieving the illusive goals of improved transparency, efficiency, awareness and engagement, ultimately leading to better policies for a better European Union.

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Twellmeyer, James; Hutter, Marco; Behrisch, Michael; Kohlhammer, Jörn; Schreck, Tobias

The Visual Exploration of Aggregate Similarity for Multi-dimensional Clustering

2015

Braz, José (Ed.) et al.: IVAPP 2015. Proceedings : 6th International Conference on Information Visualization Theory and Applications. SciTePress, 2015, pp. 40-50

International Conference on Information Visualization Theory and Applications (IVAPP) <6, 2015, Berlin, Germany>

We present a visualisation prototype for the support of a novel approach to clustering called TRIAGE. TRIAGE uses aggregation functions which are more adaptable and flexible than the weighted mean for similarity modelling. While TRIAGE has proven itself in practice, the use of complex similarity models makes the interpretation of TRIAGE clusterings challenging. We address this challenge by providing analysts with a linked, matrix-based visualisation of all relevant data attributes. We employ data sampling and matrix seriation to support both effective overviews and fluid, interactive exploration using the same visual metaphor for heterogeneous attributes. The usability of our prototype is demonstrated and assessed with the help of real-world usage scenarios from the cyber-security domain.

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Bernard, Jürgen; Daberkow, Debora; Fellner, Dieter W.; Fischer, Katrin; Koepler, Oliver; Kohlhammer, Jörn; Runnwerth, Mila; Ruppert, Tobias; Schreck, Tobias; Sens, Irina

VisInfo: A Digital Library System for Time Series Research Data Based on Exploratory Search - a User-centered Design Approach

2015

International Journal on Digital Libraries, Vol.16 (2015), 1, pp. 37-59

To this day, data-driven science is a widely accepted concept in the digital library (DL) context (Hey et al. in The fourth paradigm: data-intensive scientific discovery. Microsoft Research, 2009). In the same way, domain knowledge from information visualization, visual analytics, and exploratory search has found its way into the DL workflow. This trend is expected to continue, considering future DLchallenges such as content-based access to newdocument types, visual search, and exploration for information landscapes, or big data in general. To cope with these challenges, DL actors need to collaborate with external specialists from different domains to complement each other and succeed in given tasks such as making research data publicly available. Through these interdisciplinary approaches, the DL ecosystem may contribute to applications focused on data-driven science and digital scholarship. In this work, we present Vis- Info (2014) , a web-based digital library system (DLS) with the goal to provide visual access to time series research data. Based on an exploratory search (ES) concept (White and Roth in Synth Lect Inf Concepts Retr Serv 1(1):1-98, 2009), VisInfo at first provides a content-based overview visualization of large amounts of time series research data. Further, the system enables the user to define visual queries by example or by sketch. Finally, VisInfo presents visual-interactive capability for the exploration of search results. The development process of VisInfo was based on the user-centered design principle. Experts from computer science, a scientific digital library, usability engineering, and scientists from the earth, and environmental sciences were involved in an interdisciplinary approach. We report on comprehensive user studies in the requirement analysis phase based on paper prototyping, user interviews, screen casts, and user questionnaires. Heuristic evaluations and two usability testing rounds were applied during the system implementation and the deployment phase and certify measurable improvements for our DLS. Based on the lessons learned in VisInfo, we suggest a generalized project workflow that may be applied in related, prospective approaches.

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Steiger, Martin; Bernard, Jürgen; Schader, Philipp; Kohlhammer, Jörn

Visual Analysis of Relations in Attributed Time-Series Data

2015

Bertini, Enrico (Ed.) et al.: EuroVA 2015 : EuroVis Workshop on Visual Analytics. Goslar: Eurographics Association, 2015, pp. 61-65

International EuroVis Workshop on Visual Analytics (EuroVA) <6, 2015, Cagliari, Sardinia, Italy>

In this paper, we present visual-interactive techniques for revealing relations between two co-existing multivariate feature spaces. Such data is generated, for example, by sensor networks characterized by a set of (categorical) attributes which continuously measure physical quantities over time. A challenging analysis task is the seeking for interesting relations between the time-oriented data and the sensor attributes. Our approach uses visualinteractive analysis to enable analysts to identify correlations between similar time series and similar attributes of the data. It is based on a combination of machine-based encoding of this information in position and color and the human ability to recognize cohesive structures and patterns. In our figures, we illustrate how analysts can identify similarities and anomalies between time series and categorical attributes of metering devices and sensors.

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Koldijk, Saskia; Bernard, Jürgen; Ruppert, Tobias; Kohlhammer, Jörn; Neerincx, Mark A.; Kraaij, Wessel

Visual Analytics of Work Behavior Data - Insights on Individual Differences

2015

Kozlíková, Barbora (Ed.) et al.: Eurographics Conference on Visualization (EuroVis) - Short Papers. Goslar: Eurographics Association, 2017, pp. 79-83

Eurographics Conference on Visualization (EuroVis) <17, 2015, Cagliari, Sardinia, Italy>

Stress in working environments is a recent concern. We see potential in collecting sensor data to detect patterns in work behavior with potential danger to well-being. In this paper, we describe how we applied visual analytics to a work behavior dataset, containing information on facial expressions, postures, computer interactions, physiology and subjective experience. The challenge is to interpret this multi-modal low level sensor data. In this work, we alternate between automatic analysis procedures and data visualization. Our aim is twofold: 1) to research the relations of various sensor features with (stress related) mental states, and 2) to develop suitable visualization methods for insight into a large amount of behavioral data. Our most important insight is that people differ a lot in their (stress related) work behavior, which has to be taken into account in the analyses and visualizations.

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Ruppert, Tobias; Dambruch, Jens; Krämer, Michel; Balke, Tina; Gavanelli, Marco; Bragaglia, Stefano; Chesani, Federico; Milano, Michela; Kohlhammer, Jörn

Visual Decision Support for Policy Making: Advancing Policy Analysis with Visualization

2015

Janssen, Marijn (Ed.) et al.: Policy Practice and Digital Science : Integrating Complex Systems, Social Simulation and Public Administration in Policy Research. Springer International Publishing, 2015. (Public Administration and Information Technology 10), pp. 321-353

Today's politicians are confronted with new information technologies to tackle complex decision-making problems. In order to make sustainable decisions, a profound analysis of societal problems and possible solutions (policy options) needs to be performed. In this policy-analysis process, different stakeholders are involved. Besides internal direct advisors of the policy makers (policy analysts), external experts from different scientific disciplines can support evidence-based decision making. Despite the alleged importance of scientific advice in the policy-making process, it is observed that scientific results are often not used. In this work, a concept is described that supports the collaboration between scientists and politicians. We propose a science-policy interface that is realized by including information visualization in the policy-analysis process. Therefore, we identify synergy effects between both fields and introduce a methodology for addressing the current challenges of science-policy interfaces with visualization. Finally, we describe three exemplary case studies carried out in European research projects that instantiate the concept of this approach.

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Nazemi, Kawa; Retz, Reimond; Burkhardt, Dirk; Kuijper, Arjan; Kohlhammer, Jörn; Fellner, Dieter W.

Visual Trend Analysis with Digital Libraries

2015

Lindstaedt, Stefanie (Ed.) et al.: i-KNOW 2015 : Proceedings of the 15th International Conference on Knowledge Technologies and Data-driven Business. New York: ACM, 2015. (ACM International Conference Proceedings Series 1098), pp. 14:1-14:8

International Conference on Knowledge Management and Data-driven Business (I-KNOW) <15, 2015, Graz, Austria>

The early awareness of new technologies and upcoming trends is essential for making strategic decisions in enterprises and research. Trends may signal that technologies or related topics might be of great interest in the future or obsolete for future directions. The identification of such trends premises analytical skills that can be supported through trend mining and visual analytics. Thus the earliest trends or signals commonly appear in science, the investigation of digital libraries in this context is inevitable. However, digital libraries do not provide sufficient information for analyzing trends. It is necessary to integrate data, extract information from the integrated data and provide effective interactive visual analysis tools. We introduce in this paper a model that investigates all stages from data integration to interactive visualization for identifying trends and analyzing the market situation through our visual trend analysis environment. Our approach improves the visual analysis of trends by investigating the entire transformation steps from raw and structured data to visual representations.

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Ruppert, Tobias; Bernard, Jürgen; Lücke-Tieke, Hendrik; May, Thorsten; Kohlhammer, Jörn

Visual-Interactive Text Analysis to Support Political Decision Making - From Sentiments to Arguments to Policies

2015

Bertini, Enrico (Ed.) et al.: EuroVA 2015 : EuroVis Workshop on Visual Analytics. Goslar: Eurographics Association, 2015, pp. 37-41

International EuroVis Workshop on Visual Analytics (EuroVA) <6, 2015, Cagliari, Sardinia, Italy>

Political decision making involves the evaluation of alternative solutions (so called policy models) to a given societal problem and the selection of the most promising one. Large amounts of textual information to be considered in decision making processes can be found on the web. This includes general information about policy models, individual arguments in favor or against these policies, and public opinions. Monitoring large text collections and extracting the relevant information is time consuming. In this approach we present a visual analytics system that supports users in assessing the results of automatic text analysis methods. The methods extract text segments from large document collections and associate them with predefined policy domains, policy models, and policy arguments. Moreover, sentiment analysis is applied on the text segments. Visualization techniques provide non-IT experts an intuitive access to the results. With the system, users can monitor public debates on the web. In addition, we analyze concepts that enable the user to give visual-interactive feedback on the text analysis results. This direct user feedback can help to improve the accuracy of individual text analysis modules and the credibility of the overall text analysis process. The system was tested with real users from the political decision making domain.

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Twellmeyer, James; Kuijper, Arjan; Kohlhammer, Jörn

WOW-A-Cluster! A Visual Similarity-Based Approach to Log Exploration

2015

Peters, Christopher E. (Ed.) et al.: Proceedings of SIGRAD 2015. Linköping: Linköping University Electronic Press, 2015. (Linköping Electronic Conference Proceedings 120), pp. 61-64

SIGRAD Conference <14, 2015, Stockholm, Sweden>

We present our work on a visual, similarity-based approach to log file exploration. The use of similarity rather than simple aggregation schemes empowers users to focus on the high-level events behind log entries, rather than the entries themselves. We make use of an accelerated version of TRIAGE to determine the similarity coefficients for each pair of log entries. The model is embedded in an interactive visualization system which enables the fluid interpretation of similarities with the help of a simple clustering approach.

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Steiger, Martin; Bernard, Jürgen; May, Thorsten; Kohlhammer, Jörn

A Survey of Direction-Preserving Layout Strategies

2014

Gutierrez, Diego (Ed.): Proceedings of the 30th Spring Conference on Computer Graphics : SCCG 2014. New York: ACM, 2014, pp. 21-28

Spring Conference on Computer Graphics (SCCG) <30, 2014, Smolenice, Slovakia>

In this paper we analyze different layout algorithms that preserve relative directions in geo-referenced networks. This is an important criterion for many sensor networks such as the electric grid and other supply networks, because it enables the user to match the geographic setting with the drawing on the screen. Even today, the layouts of these networks are often created manually. This is due to the requirement that these layouts must respect geographic references but should still be easy to read and understand. The range of available automatic algorithms spans from general graph layouts over schematic maps to semi-realistic drawings. At first sight, schematics seem to be a promising compromise between geographic correctness and readability. The former property exploits the mental map of the user while the latter makes it easier for the user to learn about the network structure. We investigate different algorithms for such maps together with different visualization techniques. In particular, the group of octi-linear layouts is prominent in handcrafted subway maps. These algorithms have been used extensively to generate drawings for subway maps. Also known as Metro Map layouts, only horizontal, vertical and diagonal directions are allowed. This increases flexibility and makes the resulting layout look similar to the well-known subway maps of large cities. The key difference to general graph layout algorithms is that geographic relations are respected in terms of relative directions. However, it is not clear, whether this metaphor can be transferred from metro maps to other domains. We discuss applicability of these different approaches for geo-based networks in general with the electric grid as a use-case scenario

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Fischer, Fabian; Davey, James; Fuchs, Johannes; Thonnard, Olivier; Kohlhammer, Jörn; Keim, Daniel A.

A Visual Analytics Field Experiment to Evaluate Alternative Visualizations for Cyber Security Applications

2014

Pohl, Margit (Ed.) et al.: EuroVA 2014 : International EuroVis Workshop on Visual Analytics. Goslar: Eurographics Association, 2014, pp. 43-47

International EuroVis Workshop on Visual Analytics (EuroVA) <5, 2014, Swansea, Wales, UK>

The analysis and exploration of emerging threats in the Internet is important to better understand the behaviour of attackers and develop new methods to enhance cyber security. Fully automated algorithms alone are often not capable of providing actionable insights about the threat landscape. We therefore combine a multi-criteria clustering algorithm, tailor-made for the identification of such attack campaigns with three interactive visualizations, namely treemap representations, interactive node-link diagrams, and chord diagrams, to allow the analysts to visually explore and make sense of the resulting multi-dimensional clusters. To demonstrate the potential of the system, we share our lessons learned in conducting a field experiment with experts in a security response team and show how it helped them to gain new insights into various threat landscapes.

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Nazemi, Kawa; Burkhardt, Dirk; Retz, Reimond; Kuijper, Arjan; Kohlhammer, Jörn

Adaptive Visualization of Linked-Data

2014

Bebis, George (Ed.) et al.: Advances in Visual Computing. 10th International Symposium, ISVC 2014 : Proceedings, Part II. Berlin, Heidelberg, New York: Springer, 2014. (Lecture Notes in Computer Science (LNCS) 8888), pp. 872-883

International Symposium on Visual Computing (ISVC) <10, 2014, Las Vegas, NV, USA>

Adaptive visualizations reduces the required cognitive effort to comprehend interactive visual pictures and amplify cognition. Although the research on adaptive visualizations grew in the last years, the existing approaches do not consider the transformation pipeline from data to visual representation for a more efficient and effective adaptation. Further todays systems commonly require an initial training by experts from the field and are limited to adaptation based either on user behavior or on data characteristics. A combination of both is not proposed to our knowledge. This paper introduces an enhanced instantiation of our previously proposed model that combines both: involving different influencing factors for and adapting various levels of visual peculiarities, on content, visual layout, visual presentation, and visual interface. Based on data type and users' behavior, our system adapts a set of applicable visualization types. Moreover, retinal variables of each visualization type are adapted to meet individual or canonical requirements on both, data types and users' behavior. Our system does not require an initial expert modeling.

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Nazemi, Kawa; Burkhardt, Dirk; Retz, Wilhelm; Kohlhammer, Jörn

Adaptive Visualization of Social Media Data for Policy Modeling

2014

Bebis, George (Ed.) et al.: Advances in Visual Computing. 10th International Symposium, ISVC 2014 : Proceedings, Part I. Berlin, Heidelberg, New York: Springer, 2014. (Lecture Notes in Computer Science (LNCS) 8887), pp. 333-344

International Symposium on Visual Computing (ISVC) <10, 2014, Las Vegas, NV, USA>

The visual analysis of social media data emerged a huge number of interactive visual representations that use different characteristics of the data to enable the process of information acquisition. The social data are used in the domain of policy modeling to gather information about citizens' demands, opinions, and requirements and help to decide about political policies. Although existing systems already provide a huge number of visual analysis tools, the search and exploration paradigm is not really clear. Furthermore, the systems commonly do not provide any kind of human centered adaptation for the different stakeholders involved in the policy making process. In this paper, we introduce a novel approach that investigates the exploration and search paradigm from two different perspectives and enables a visual adaptation to support the exploration and analysis process.

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Ruppert, Tobias; Bernard, Jürgen; May, Thorsten; Kohlhammer, Jörn

Combining Computational Models and Interactive Visualization to Support Rational Decision Making

2014

Bebis, George (Ed.) et al.: Advances in Visual Computing. 10th International Symposium, ISVC 2014 : Proceedings, Part I. Berlin, Heidelberg, New York: Springer, 2014. (Lecture Notes in Computer Science (LNCS) 8887), pp. 345-356

International Symposium on Visual Computing (ISVC) <10, 2014, Las Vegas, NV, USA>

Decision making is a complex process consisting of several consecutive steps. Before converting a decision into effective action the problem to be tackled needs to be analyzed, alternative solutions need to be developed, and the best solution needs to be picked. In many cases computational models support decision makers in this process. Therefore, providing an intuitive access to these model-driven techniques is crucial. In this approach, we introduce a decision support system that provides visual-interactive access to three computational models - a simulation model, an optimization model, and an opinion mining model - covering different aspects of decision making. For each model our decision support system realizes the visual access to the model, an in-depth analysis of the generated solutions, and the comparison of alternative solutions. Finally, we evaluate the usefulness and the usability of our system in a use case in the field of public policy making.

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Burkhardt, Dirk; Nazemi, Kawa; Klamm, Christopher; Kohlhammer, Jörn; Kuijper, Arjan

Comparison of e-Participation Roadmap in Industrial and Developing Countries based on Germany and Kenya

2014

Estevez, Elsa (Ed.) et al.: ICEGOV 2014 : Proceedings of the 8th International Conference on Theory and Practice of Electronic Governance. New York: ACM Press, 2014, pp. 399-402

International Conference on Theory and Practice of Electronic Governance (ICEGOV) <8, 2014, Guimaraes, Portugal>

This paper compares the E-Participation roadmaps of industrial and developing countries, based on Germany and Kenya as representatives. Therefore, the ICT roadmap of each country is de-scribed in a clear shape and with representative E-Participation projects of each country. Based on these projects, the comparison is performed on a categorical level in terms of (1) participation forms, (2) used ICT, and (3) socio-political requirements. After-wards, the results are summarized to determine an overall view on the E-Participation situation in both countries. As a result of the comparison similarities and significant differences will be identified. The results are useful for software developing organizations that want to create ICT governance tools for industrial as well as developing countries and therefore need to consider the characteristics and requirements of both country types.

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Steiger, Martin; Lücke-Tieke, Hendrik; May, Thorsten; Kuijper, Arjan; Kohlhammer, Jörn

Deterministic Local Layouts through High-Dimensional Layout Stitching

2014

Kurosu, Masaaki (Ed.): Human-Computer Interaction: Part 1 : Theories, Methods, and Tools. HCI International 2014. Berlin, Heidelberg, New York: Springer, 2014. (Lecture Notes in Computer Science (LNCS) 8510), pp. 643-651

International Conference on Human-Computer Interaction (HCII) <16, 2014, Heraklion, Crete, Greece>

In this paper we present a layout technique for dynamic views of large static graphs. It aims to minimize changes between two consecutive frames and most importantly, it is deterministic. First, a set of small layout patches is pre-computed. Then, depending on the users view focus, a subset of these patches is selected and connected to generate the final layout. In contrast to the state-of-the-art approach that operates in the 2D screen space only, we perform this process in high-dimensional space before projecting the results into the 2D plane. This gives additional degrees of freedom and consequently a smoother transition process between two consecutive frames. Whenever the user visits an area of the graph for a second time, the layout will still look the same. This enables the user to recognize areas that have already been explored and thus preserve the mental map.

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Konstantinos, Votis; Karras, Yiannis; Kohlhammer, Jörn; Steiger, Martin; Tzovaras, Dimitrios; Gounopoulos, Elias

Enhanced Visual Analytics Services for the Optimal Planning of Renewable Energy Resources Installations

2014

Iliadis, Lazaros (Ed.) et al.: Artificial Intelligence Applications and Innovations : AIAI 2014 Workshops: CoPA, MHDW, IIVC, and MT4BD. Berlin, Heidelberg, New York: Springer, 2014. (IFIP Advances in Information and Communication Technology 437), pp. 330-339

International Conference on Artificial Intelligence Applications and Innovations (AIAI) <10, 2014, Rhodes, Greece>

This paper presents an integrated and novel service environment for real-time interactions between users, as well as enhanced visualization and decision support services over extremely large volumes of heterogeneous Renewable data sources. The integrated visual analytics methods, allow energy analysts to incorporate their expert knowledge into the analysis, so as to dynamically investigate the observed events and locations, and accurately identify the preferable results. The goal of visual analytics research is to turn the information overload into an opportunity by enabling decision-makers to examine this massive amount of information to make effective decisions.

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Steiger, Martin; Hutter, Marco; Schader, Philipp; Kohlhammer, Jörn; Kuijper, Arjan

Exploring Simulation in Sensor Network Models

2014

Bender, Jan (Ed.) et al.: VMV 2014 : Vision, Modeling, and Visualization. Goslar: Eurographics Association, 2014, pp. 135-142

Workshop on Vision, Modeling, and Visualization (VMV) <19, 2014, Darmstadt, Germany>

Simulation is an important measure to estimate different properties of a planned network such as throughput and cost. However, many parameters need to be adjusted to approximate real-world conditions properly. In this paper we present a visualization system that visually supports and guides the analysis of (physical) network simulation problems. Automatic optimizers run as a black box giving an (locally) optimal result in terms of the underlying simulation model and parameter configuration. This is often not ideal for practical usage. Our system assists the user in the process of comparing different simulations to quickly achieve the optimal configuration in terms of user preference. It highlights differences between simulation runs and indicates which parameter modification leads to the best improvement. We expect that this results in large time savings for the domain expert while configuring the simulation system.

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May, Thorsten; Nazemi, Kawa; Kohlhammer, Jörn

From Raw Data to Rich Visualization: Combining Visual Search with Data Analysis

2014

Wahlster, Wolfgang (Ed.) et al.: Towards the Internet of Services: The THESEUS Research Program. Berlin, Heidelberg, New York: Springer, 2014. (Cognitive Technologies), pp. 203-209

Visual analytics is an interdisciplinary field of research at the boundary between data mining, statistics and visualization. Patterns and relations in the data complement a semantic representation of knowledge on a lower level of abstraction. One important goal of visual analytics is to find relations hidden in vast amounts of data, which can be turned into useful knowledge. Analysis needs to be "visual", because human's visual cognitive abilities are important for the identification and refinement of the analytical process. Further the results of the analysis have to be presented in a way to match the user's perspective on the proposed task. However, typical users are not experts in statistics or data mining. The challenge of visual analytics is to keep domain experts in charge of the analytical process while reducing the workload due to the complexity of the techniques. While search and analysis usually arc mentioned in different contexts, they are highly interdependent processes. In fact, every exploratory analysis is a search for new knowledge. In turn, this knowledge can be used to refine future searches by introducing new concepts or relations to draw from. This article will show how automated and visual methods can be combined to connect knowledge artifacts on multiple levels of abstraction.

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Burkhardt, Dirk; Nazemi, Kawa; Zilke, Jan Ruben; Kohlhammer, Jörn; Kuijper, Arjan

Fundamental Aspects for E-Government

2014

Sonntagbauer, Peter et al.: Handbook of Research on Advanced ICT Integration for Governance and Policy Modeling. Hershey, Pennsylvania: IGI Global, 2014, pp. 1-18

The upcoming initiatives using ICT in the government process should strengthen the benefit of E-Government in most countries. Since E-Government among other e-related terms is a widely (interpreted) term, it is sometimes challenging to understand the objective and goals of an initiative. Therefore in this paper we introduce and explain the most E-Government related terms. Even more, we outline some interesting initiatives and implementations to explain the benefits of using ICT in the government domain. So next to the term description, concrete activities will be aligned to the terms to explain the practical use in a better way. We conclude with several challenges that arise when thinking of the implementation of E-Government services. Overall this chapter should give a good overall view about E-Government and the relating issues.

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Nazemi, Kawa; Steiger, Martin; Burkhardt, Dirk; Kohlhammer, Jörn

Information Visualization and Policy Modeling

2014

Sonntagbauer, Peter et al.: Handbook of Research on Advanced ICT Integration for Governance and Policy Modeling. Hershey, Pennsylvania: IGI Global, 2014, pp. 145-215

Policy design requires the investigation of various data in several design steps for making the right decisions, validating, or monitoring the political environment. The increasing amount of data is challenging for the stakeholders in this domain. One promising way to access the "big data" is by abstracted visual patterns and pictures, as proposed by information visualization. This chapter introduces the main idea of information visualization in policy modeling. First abstracted steps of policy design will be introduced that enables the identification of information visualization need in the entire policy lifecycle. Thereafter the foundations of information visualization will be introduced based on an established reference model. We aim to amplify the incorporation of information visualization in the entire policy design process. Therefore the aspects of data and human interaction will be introduced too. The foundation leads to description of a conceptual design for social data visualization, whereas the aspect of semantics plays an important role.

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Nazemi, Kawa; Kuijper, Arjan; Hutter, Marco; Kohlhammer, Jörn; Fellner, Dieter W.

Measuring Context Relevance for Adaptive Semantics Visualizations

2014

Lindstaedt, Stefanie (Ed.) et al.: i-KNOW 2014 : Proceedings of the 14th International Conference on Knowledge Technologies and Data-driven Business. New York: ACM, 2014. (ACM International Conference Proceedings Series 889), Article 14, 8 p.

International Conference on Knowledge Technologies and Data-driven Business (I-KNOW) <14, 2014, Graz, Austria>

Semantics visualizations enable the acquisition of information to amplify the acquisition of knowledge. The dramatic increase of semantics in form of Linked Data and Linked-Open Data yield search databases that allow to visualize the entire context of search results. The visualization of this semantic context enables one to gather more information at once, but the complex structures may as well confuse and frustrate users. To overcome the problems, adaptive visualizations already provide some useful methods to adapt the visualization on users' demands and skills. Although these methods are very promising, these systems do not investigate the relevance of semantic neighboring entities that commonly build most information value. We introduce two new measurements for the relevance of neighboring entities: The Inverse Instance Frequency allows weighting the relevance of semantic concepts based on the number of their instances. The Direct Relation Frequency inverse Relations Frequency measures the relevance of neighboring instances by the type of semantic relations. Both measurements provide a weighting of neighboring entities of a selected semantic instance, and enable an adaptation of retinal variables for the visualized graph. The algorithms can easily be integrated into adaptive visualizations and enhance them with the relevance measurement of neighboring semantic entities. We give a detailed description of the algorithms to enable a replication for the adaptive and semantics visualization community. With our method, one can now easily derive the relevance of neighboring semantic entities of selected instances, and thus gain more information at once, without confusing and frustrating users.

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Burkhardt, Dirk; Nazemi, Kawa; Kohlhammer, Jörn

Policy Modeling Methodologies

2014

Sonntagbauer, Peter et al.: Handbook of Research on Advanced ICT Integration for Governance and Policy Modeling. Hershey, Pennsylvania: IGI Global, 2014, pp. 48-60

The process to develop sustainable public policies is precisely defined in public authorities to ensure the involvement of all stakeholders and to ensure the creation of an effective policy. The inclusion of ICT in most of the today's applied policy making processes in public authorities is mostly less considered. Indeed, other process definitions with focus on ICT inclusion in policy modeling still exist, but they are mostly not well defined. This chapter gives an overview about the existing policy modeling process types and explains their major focus and how they consider ICT and the practical process in public authorities. Afterwards based on these descriptions the general requirements on a new ICT-oriented policy modeling process that allows the inclusion of ICT into a valid and useful process for public authorities will be given.

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Mittelstädt, Sebastian; Bernard, Jürgen; Schreck, Tobias; Steiger, Martin; Kohlhammer, Jörn; Keim, Daniel A.

Revisiting Perceptually Optimized Color Mapping for High-Dimensional Data Analysis

2014

Elmqvist, N. (Ed.) et al.: EuroVis - Short Papers 2014. Goslar: Eurographics Association, 2014, pp. 91-95

Eurographics Conference on Visualization (EuroVis) <16, 2014, Swansea, Wales, UK>

Colors is one of the most effective visual variables since it can be combined with other mappings and encode information without using any additional space on the display. An important example where expressing additional visual dimensions is direly needed is the analysis of high-dimensional data. The property of perceptual linearity is desirable in this application, because the user intuitively perceives clusters and relations among multi-dimensional data points. Many approaches use two-dimensional colormaps in their analysis, which are typically created by interpolating in RGB, HSV or CIELAB color spaces. These approaches share the problem that the resulting colors are either saturated and discriminative but not perceptual linear or vice versa. A solution that combines both advantages has been previously introduced by Kaski et al.; yet, this method is to date underutilized in Information Visualization according to our literature analysis. The method maps high-dimensional data points into the CIELAB color space by maintaining the relative perceived distances of data points and color discrimination. In this paper, we generalize and extend the method of Kaski et al. to provide perceptual uniform color mapping for visual analysis of high-dimensional data. Further, we evaluate the method and provide guidelines for different analysis tasks.

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Nazemi, Kawa; Breyer, Matthias; Burkhardt, Dirk; Stab, Christian; Kohlhammer, Jörn

SemaVis: A New Approach for Visualizing Semantic Information

2014

Wahlster, Wolfgang (Ed.) et al.: Towards the Internet of Services: The THESEUS Research Program. Berlin, Heidelberg, New York: Springer, 2014. (Cognitive Technologies), pp. 191-202

Information is an indispensable resource today. Access to and interaction with information play more and more a key role, whereas the amount of accessible information increases. Semantic technologies provide new solutions to structure this important property. One promising way to access the complex semantic structures and the huge amount of data is visualization. Today's Semantic Visualization systems offer primarily proprietary solutions for predefined and known users and usage scenarios. The adaptation to other scenarios and users is often cost-and time-consuming. This article presents a novel model for a fully adaptable and adaptive Semantics Visualization framework. Starling with the introduction of a new visualization model, the implementation of this model will be described. The article concludes with selected advantages of the described visualization technology.

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Steiger, Martin; May, Thorsten; Kohlhammer, Jörn

Stable Incremental Layouts for Dynamic Graph Visualizations

2014

IADIS International Journal on Computer Science and Information Systems, Vol.8 (2014), 2, pp. 12-26

In this paper we present a set of extension techniques to stabilize interactive dynamic graph layout algorithms. It works with different existing Focus & Context methods. We first deal with the initial placement of newly inserted nodes to mitigate acting forces in the layout algorithm. Then, their influence on the existing layout is gradually increased to create a smooth transition between the old and the new layout. To complement this approach we use a look-ahead strategy that integrates additional nodes in the layout to stabilize the layout even more. Our approach is validated using both quantitative and qualitative measures.

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Ruppert, Tobias; Bernard, Jürgen; Lücke-Tieke, Hendrik; Kohlhammer, Jörn

Towards a Tighter Coupling of Visualization and Public Policy Making

2014

Chen, Min (Ed.) et al.: IEEE Conference on Visual Analytics Science and Technology. Proceedings : VAST 2014. Los Alamitos, Calif.: IEEE Computer Society, 2014, pp. 271-272

IEEE Symposium on Visual Analytics Science and Technology (VAST) <9, 2014, Paris, France>

The purpose of this ongoing work is to motivate public policy making as an application area for information visualization and visual analytics. Through our expertise gathered in several policy making related projects, we identified parallels between the benefits of visualization and the needs of evidence-based public policy making. In the following, we will share our previous work consisting of the conceptual introduction of information visualization and visual analytics into the application field of public policy making. Moreover, we will show two real-world cases applying this concept. Finally, we will share identified challenges to be addressed by the information visualization and visual analytics domains in the future.

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Bernard, Jürgen; Hutter, Marco; Sessler, David; Schreck, Tobias; Behrisch, Michael; Kohlhammer, Jörn

Towards a User-Defined Visual-Interactive Definition of Similarity Functions for Mixed Data

2014

Chen, Min (Ed.) et al.: IEEE Conference on Visual Analytics Science and Technology. Proceedings : VAST 2014. Los Alamitos, Calif.: IEEE Computer Society, 2014, pp. 227-228

IEEE Symposium on Visual Analytics Science and Technology (VAST) <9, 2014, Paris, France>

The creation of similarity functions based on visual-interactive user feedback is a promising means to capture the mental similarity notion in the heads of domain experts. In particular, concepts exist where users arrange multivariate data objects on a 2D data landscape in order to learn new similarity functions. While systems that incorporate numerical data attributes have been presented in the past, the remaining overall goal may be to develop systems also for mixed data sets. In this work, we present a feedback model for categorical data which can be used alongside of numerical feedback models in future.

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Nazemi, Kawa; Retz, Wilhelm; Kohlhammer, Jörn; Kuijper, Arjan

User Similarity and Deviation Analysis for Adaptive Visualizations

2014

Yamamoto, Sakae (Ed.): Human Interface and the Management of Information. Proceedings Part I : Information and Interaction for Learning, Culture, Collaboration and Business.. Berlin, Heidelberg, New York: Springer, 2014. (Lecture Notes in Computer Science (LNCS) 8521), pp. 64-75

International Conference on Human Interface and the Management of Information (HIMI) <2014, Heraklion, Crete, Greece>

Adaptive visualizations support users in information acquisition and exploration and therewith in human access of data. Their adaptation effect is often based on approaches that require the training by an expert. Further the effects often aim to support just the individual aptitudes. This paper introduces an approach for modeling a canonical user that makes the predefined training-files dispensable and enables an adaptation of visualizations for the majority of users. With the introduced user deviation algorithm, the behavior of individuals can be compared to the average user behavior represented in the canonical user model to identify behavioral anomalies. The further introduced similarity measurements allow to cluster similar deviated behavioral patterns as groups and provide them effective visual adaptations.

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Bernard, Jürgen; Sessler, David; Ruppert, Tobias; Davey, James; Kuijper, Arjan; Kohlhammer, Jörn

User-Based Visual-Interactive Similarity Definition for Mixed Data Objects - Concept and First Implementation

2014

Skala, Vaclav (Ed.): WSCG 2014. Communication Papers Proceedings : 22nd International Conference in Central Europe on Computer Graphics, Visualization and Computer Vision. Plzen: University of West Bohemia, 2014, pp. 329-338

International Conference in Central Europe on Computer Graphics, Visualization and Computer Vision (WSCG) <22, 2014, Plzen, Czech Republic>

The definition of similarity between data objects plays a key role in many analytical systems. The process of similarity definition comprises several challenges as three main problems occur: different stakeholders, mixed data, and changing requirements. Firstly, in many applications the developers of the analytical system (data scientists) model the similarity, while the users (domain experts) have distinct (mental) similarity notions. Secondly, the definition of similarity for mixed data types is challenging. Thirdly, many systems use static similarity models that cannot adapt to changing data or user needs. We present a concept for the development of systems that support the visual-interactive similarity definition for mixed data objects emphasizing 15 crucial steps. For each step different design considerations and implementation variants are presented, revealing a large design space. Moreover, we present a first implementation of our concept, enabling domain experts to express mental similarity notions through a visual-interactive system. The provided implementation tackles the different-stakeholders problem, the mixed data problem, and the changing requirements problem. The implementation is not limited to a specific mixed data set. However, we show the applicability of our implementation in a case study where a functional similarity model is trained for countries as objects.

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Ruppert, Tobias; Bernard, Jürgen; Ulmer, Alex; Lücke-Tieke, Hendrik; Kohlhammer, Jörn

Visual Access to an Agent-based Simulation Model to Support Political Decision Making

2014

Lindstaedt, Stefanie (Ed.) et al.: i-KNOW 2014 : Proceedings of the 14th International Conference on Knowledge Technologies and Data-driven Business. New York: ACM, 2014. (ACM International Conference Proceedings Series 889), Article 16, 8 p.

International Conference on Knowledge Technologies and Data-driven Business (I-KNOW) <14, 2014, Graz, Austria>

Decision making in the field of policy making is a complex task. On the one hand conflicting objectives influence the availability of alternative solutions for a given problem. On the other hand economic, social, and environmental impacts of the chosen solution have to be considered. In the political context, these solutions are called policy options. To tackle societal problems a thorough analysis of policy options needs to be executed before a policy can be put into practice. Computational simulation is a method considered for measuring the impacts of policy options. However, due to their complexity, the underlying models and their output may be difficult to access by decision makers. In this work, we present a visual-interactive interface for an agent-based simulation model that enables decision makers to evaluate the impacts of alternative policy options in the field of regional energy planning. The decision maker can specify different subsidy strategies for supporting public photovoltaic installations as input and evaluate their impact on the actual adoption via the simulation output. We show the usability and usefulness of the visual interface in a real-world example evolved from the European research project ePolicy.

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Behrisch, Michael; Davey, James; Fischer, Fabian; Thonnard, Olivier; Schreck, Tobias; Keim, Daniel A.; Kohlhammer, Jörn

Visual Analysis of Sets of Heterogeneous Matrices Using Projection-Based Distance Functions and Semantic Zoom

2014

Computer Graphics Forum, Vol.33 (2014), 3, pp. 411-420

Eurographics Conference on Visualization (EuroVis) <16, 2014, Swansea, Wales, UK>

Matrix visualization is an established technique in the analysis of relational data. It is applicable to large, dense networks, where node-link representations may not be effective. Recently, domains have emerged in which the comparative analysis of sets of matrices of potentially varying size is relevant. For example, to monitor computer network traffic a dynamic set of hosts and their peer-to-peer connections on different ports must be analysed. A matrix visualization focused on the display of one matrix at a time cannot cope with this task. We address the research problem of the visual analysis of sets of matrices. We present a technique for comparing matrices of potentially varying size. Our approach considers the rows and/or columns of a matrix as the basic elements of the analysis. We project these vectors for pairs of matrices into a low-dimensional space which is used as the reference to compare matrices and identify relationships among them. Bipartite graph matching is applied on the projected elements to compute a measure of distance. A key advantage of this measure is that it can be interpreted and manipulated as a visual distance function, and serves as a comprehensible basis for ranking, clustering and comparison in sets of matrices. We present an interactive system in which users may explore the matrix distances and understand potential differences in a set of matrices. A flexible semantic zoom mechanism enables users to navigate through sets of matrices and identify patterns at different levels of detail. We demonstrate the effectiveness of our approach through a case study and provide a technical evaluation to illustrate its strengths.

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Steiger, Martin; Bernard, Jürgen; Mittelstädt, Sebastian; Lücke-Tieke, Hendrik; Keim, Daniel A.; May, Thorsten; Kohlhammer, Jörn

Visual Analysis of Time-Series Similarities for Anomaly Detection in Sensor Networks

2014

Computer Graphics Forum, Vol.33 (2014), 3, pp. 401-410

Eurographics Conference on Visualization (EuroVis) <16, 2014, Swansea, Wales, UK>

We present a system to analyze time-series data in sensor networks. Our approach supports exploratory tasks for the comparison of univariate, geo-referenced sensor data, in particular for anomaly detection. We split the recordings into fixed-length patterns and show them in order to compare them over time and space using two linked views. Apart from geo-based comparison across sensors we also support different temporal patterns to discover seasonal effects, anomalies and periodicities. The methods we use are best practices in the information visualization domain. They cover the daily, the weekly and seasonal and patterns of the data. Daily patterns can be analyzed in a clustering-based view, weekly patterns in a calendar-based view and seasonal patterns in a projection-based view. The connectivity of the sensors can be analyzed through a dedicated topological network view. We assist the domain expert with interaction techniques to make the results understandable. As a result, the user can identify and analyze erroneous and suspicious measurements in the network. A case study with a domain expert verified the usefulness of our approach.

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Burkhardt, Dirk; Nazemi, Kawa; Parisay, Mohsen; Kohlhammer, Jörn

Visual Correlation Analysis to Explain Open Government Data based on Linked-Open Data for Decision Making

2014

International Journal of Digital Society, Vol.5 (2014), 3-4, pp. 915-923

Public authorities normally consider statistical data about indicators in their decision makings. Such valid kind of data allows an objective observation about indicator developments over time. In case of a significant deviation from the normal indicator level, it is difficult to understand the reasons for upcoming problems. In this article we present an approach that allows an enhanced information gathering through an improved information overview about the depending aspects to such an indicator by considering governmental data-sources that provide also other types of data than just statistics. Even more, our approach integrates a system that allows generating explanations for Open Government Data, especially to specific indicators, based on Linked-Open Data and shows it in graphical form to enable a fast overview gathering. This allows decision-makers to get hints for unexpected reasons of concrete problems that may influence an indicator.

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Burkhardt, Dirk; Nazemi, Kawa; Retz, Wilhelm; Kohlhammer, Jörn

Visual Explanation of Government-Data for Policy Making through Open-Data Inclusion

2014

Shoniregun, Charles A. (Ed.) et al.: International Conference for Internet Technology and Secured Transactions : ICITST-2014. Los Alamitos, Calif.: IEEE Computer Society, 2014, pp. 84-90

International Conference for Internet Technology and Secured Transactions (ICITST) <9, 2014, London, UK>

Commonly, data used in public authorities are statistical data about certain indicator. Such valid kind of data allows an objective observation about indicator developments over time. In case of a significant deviation from the normal indicator level, it is difficult to understand the reasons for upcoming problems. In our paper we present an approach that allows an enhanced information gathering through an improved information overview about the depending aspects to such an indicator by considering governmental data-sources that provide also other types of data than just statistics. Even more, our approach integrates a system that allows generating explanations for Open Government Data, especially to specific indicators, based on Linked-Open Data. This enables decision-makers to get hints for unexpected reasons of concrete problems that may influence an indicator.

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Burkhardt, Dirk; Nazemi, Kawa; Kohlhammer, Jörn

Visual Process Support to Assist Users in Policy Making

2014

Sonntagbauer, Peter et al.: Handbook of Research on Advanced ICT Integration for Governance and Policy Modeling. Hershey, Pennsylvania: IGI Global, 2014, pp. 149-162

The policy making process requires the involvement of various stakeholders, who bring in very heterogeneous experiences and skills concerning the policy making domain, as well as experiences of ICT solutions. Current solutions primary designed to provide "one-solution-fits-all", which in most cases fail the needs of all stakeholders. In this paper we introduce a new approach to assist users based on their tasks. Therefore the system observes the interaction of the user and recognizes the current phase of the policy making process and the profile of the user to assist him more sufficiently in solving his task. For this purpose the system automatically enables or disables supporting features such as visualization, tools and supporting techniques.

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Bernard, Jürgen; Steiger, Martin; Widmer, Sven; Lücke-Tieke, Hendrik; May, Thorsten; Kohlhammer, Jörn

Visual-interactive Exploration of Interesting Multivariate Relations in Mixed Research Data Sets

2014

Computer Graphics Forum, Vol.33 (2014), 3, pp. 291-300

Eurographics Conference on Visualization (EuroVis) <16, 2014, Swansea, Wales, UK>

The analysis of research data plays a key role in data-driven areas of science. Varieties of mixed research data sets exist and scientists aim to derive or validate hypotheses to find undiscovered knowledge. Many analysis techniques identify relations of an entire dataset only. This may level the characteristic behavior of different subgroups in the data. Like automatic subspace clustering, we aim at identifying interesting subgroups and attribute sets. We present a visual-interactive system that supports scientists to explore interesting relations between aggregated bins of multivariate attributes in mixed data sets. The abstraction of data to bins enables the application of statistical dependency tests as the measure of interestingness. An overview matrix view shows all attributes, ranked with respect to the interestingness of bins. Complementary, a node-link view reveals multivariate bin relations by positioning dependent bins close to each other. The system supports information drill-down based on both expert knowledge and algorithmic support. Finally, visual-interactive subset clustering assigns multivariate bin relations to groups. A list-based cluster result representation enables the scientist to communicate multivariate findings at a glance. We demonstrate the applicability of the system with two case studies from the earth observation domain and the prostate cancer research domain. In both cases, the system enabled us to identify the most interesting multivariate bin relations, to validate already published results, and, moreover, to discover unexpected relations.

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Burkhardt, Dirk; Nazemi, Kawa; Encarnacao, Jose Daniel; Retz, Wilhelm; Kohlhammer, Jörn

Visualization Adaptation Based on Environmental Influencing Factors

2014

Kurosu, Masaaki (Ed.): Human-Computer Interaction: Part 1 : Theories, Methods, and Tools. HCI International 2014. Berlin, Heidelberg, New York: Springer, 2014. (Lecture Notes in Computer Science (LNCS) 8510), pp. 411-422

International Conference on Human-Computer Interaction (HCII) <16, 2014, Heraklion, Crete, Greece>

Working effectively with computer-based devices is challenging, especially under mobile conditions, due to the various environmental influences. In this paper a visualization adaptation approach is described, to support the user under discriminatory environmental conditions. For this purpose, a context model for environmental influencing factors is being defined. Based on this context model, an approach to adapt visualizations in regards of certain environmental influences is being evolved, such as the light intensity, air quality, or heavy vibrations.

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Nazemi, Kawa; Retz, Reimond; Bernard, Jürgen; Kohlhammer, Jörn; Fellner, Dieter W.

Adaptive Semantic Visualization for Bibliographic Entries

2013

Bebis, George (Ed.) et al.: Advances in Visual Computing. 9th International Symposium, ISVC 2013 : Proceedings, Part II. Berlin, Heidelberg, New York: Springer, 2013. (Lecture Notes in Computer Science (LNCS) 8034), pp. 13-24

International Symposium on Visual Computing (ISVC) <9, 2013, Rethymnon, Crete, Greece>

Adaptive visualizations aim to reduce the complexity of visual representations and convey information using interactive visualizations. Although the research on adaptive visualizations grew in the last years, the existing approaches do not make use of the variety of adaptable visual variables. Further the existing approaches often premises experts, who has to model the initial visualization design. In addition, current approaches either incorporate user behavior or data types. A combination of both is not proposed to our knowledge. This paper introduces the instantiation of our previously proposed model that combines both: involving different influencing factors for and adapting various levels of visual peculiarities, on visual layout and visual presentation in a multiple visualization environment. Based on data type and users' behavior, our system adapts a set of applicable visualization types. Moreover, retinal variables of each visualization type are adapted to meet individual or canonic requirements on both, data types and users' behavior. Our system does not require an initial expert modeling.

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Ruppert, Tobias; Bernard, Jürgen; Kohlhammer, Jörn

Bridging Knowledge Gaps in Policy Analysis with Information Visualization

2013

Wimmer, Maria A. (Ed.) et al.: Electronic Government and Electronic Participation : Joint Proceedings of Ongoing Research of IFIP EGOV and IFIP ePart 2013. Bonn: Köllen, 2013. (GI-Edition - Lecture Notes in Informatics (LNI) P-221), pp. 92-103

International conferences on Electronic GOVernment (EGOV) <2013, Koblenz, Germany>

Today's politicians are confronted with new (digital) ways to tackle complex decision-making problems. In order to make the right decisions profound analysis of the problems and possible solutions has to be performed. Therefore policy analysts need to collaborate with external experts consulted as advisors. Due to different expertises of these stakeholders the whole process may suffer from knowledge gaps. In our approach, we describe a concept to bridge these knowledge gaps by introducing information visualization and visual analytics to the policy analysis domain. Therefore, we refine a standard policy cycle at the stages relevant for the policy analysis. Secondly, we characterize the main stakeholders in the process, and identify knowledge gaps between these roles. Finally, we emphasize the merits of including advanced visualization techniques into the policy analysis process, and describe visualization as a facet bridging the knowledge gaps in a collaborative policy making life-cycle.

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Owen, G. Scott; Domik, Gitta; Ebert, David S.; Kohlhammer, Jörn; Rushmeier, Holly; Santos, Beatriz Sousa; Weiskopf, Daniel

How Visualization Courses Have Changed over the Past 10 Years

2013

IEEE Computer Graphics and Applications, Vol.33 (2013), 4, pp. 14-19

The past 10 years have seen profound changes in visualization algorithms, techniques, methodologies, and applications. These changes are forcing alterations to visualization courses. Unfortunately, outdated course content recommendations, together with profound changes in the underlying technology and methodology, are producing an unstable ground for educators at a time when visual representations are becoming increasingly important. To address this issue, educators held meetings or workshops at Siggraph 2011 and 2012 and a panel and workshop at Eurographics 2012. This article presents the insights gathered at these events.

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Burkhardt, Dirk; Nazemi, Kawa; Sonntagbauer, Peter; Kohlhammer, Jörn

Interactive Visualizations in the Process of Policy Modeling

2013

Wimmer, Maria A. (Ed.) et al.: Electronic Government and Electronic Participation : Joint Proceedings of Ongoing Research of IFIP EGOV and IFIP ePart 2013. Bonn: Köllen, 2013. (GI-Edition - Lecture Notes in Informatics (LNI) P-221), pp. 104-115

International conferences on Electronic GOVernment (EGOV) <2013, Koblenz, Germany>

The policy making process in public authorities is nowadays usually an offline process. ICT is just very conservatively used, which also limits the inclusion of citizens' opinions. In difference the ICT sector consists of a rapid development in the area of eParticitpation and also in data-storing approaches and visualizations. But today it is hard to assign such new technical approaches to the policy modeling process, because of their non-ICT orientation. In this paper we introduce a new detailed ICT-based policy modeling process and an assignment of some modern ICT technology features. To support decision-makers, the main contribution of this paper is an assignment of useful visualization-types to the technological features and furthermore to the ICT-based policy-making process. Therewith we describe an approach how interactive visualizations can lead to a more effective policy making.

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Bernard, Jürgen; Wilhelm, Nils; Krüger, Björn; May, Thorsten; Schreck, Tobias; Kohlhammer, Jörn

MotionExplorer: Exploratory Search in Human Motion Capture Data Based on Hierarchical Aggregation

2013

IEEE Transactions on Visualization and Computer Graphics, Vol.19 (2013), 12, pp. 2257-2266

IEEE Symposium on Visual Analytics Science and Technology (VAST) <8, 2013, Atlanta, GA, USA>

We present MotionExplorer, an exploratory search and analysis system for sequences of human motion in large motion capture data collections. This special type of multivariate time series data is relevant in many research fields including medicine, sports and animation. Key tasks in working with motion data include analysis of motion states and transitions, and synthesis of motion vectors by interpolation and combination. In the practice of research and application of human motion data, challenges exist in providing visual summaries and drill-down functionality for handling large motion data collections. We find that this domain can benefit from appropriate visual retrieval and analysis support to handle these tasks in presence of large motion data. To address this need, we developed MotionExplorer together with domain experts as an exploratory search system based on interactive aggregation and visualization of motion states as a basis for data navigation, exploration, and search. Based on an overview-first type visualization, users are able to search for interesting sub-sequences of motion based on a query-by-example metaphor, and explore search results by details on demand. We developed MotionExplorer in close collaboration with the targeted users who are researchers working on human motion synthesis and analysis, including a summative field study. Additionally, we conducted a laboratory design study to substantially improve MotionExplorer towards an intuitive, usable and robust design. MotionExplorer enables the search in human motion capture data with only a few mouse clicks. The researchers unanimously confirm that the system can efficiently support their work.

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Steiger, Martin; May, Thorsten; Davey, James; Kohlhammer, Jörn

Smart Grid Monitoring through Visual Analysis

2013

IEEE Power & Energy Society (PES): 2013 4th IEEE PES Innovative Smart Grid Technologies Europe : IEEE PES ISGT Europe 2013. Piscataway: IEEE, 2013, 5 p.

IEEE/PES Innovative Smart Grid Technologies Europe (ISGT Europe) <4, 2013, Copenhagen, Denmark>

In this paper we present a visualization system for the real-time monitoring of Smart Grids. In particular, it supports the control room operators of electric grids with large amounts of distributed power generation. As measurements are continuously read from connected Smart Meters, an expert system performs a classification of these events to relieve the operator from the manual inspection of irrelevant and trivial information items. A coordinated, multiple view environment displays the electric grid model which is annotated with status indicators. This gives the operator both a reasonable overview on the entire system, but also enables him to inspect specific parts in detail. Other sources of information such as ICT coverage and weather conditions are included to provide additional context. The visualization system thus provides monitoring and control support for operators to keep the grid in a stable condition.

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Steiger, Martin; May, Thorsten; Kohlhammer, Jörn

Stable Incremental Layouts for Dynamic Graph Visualizations

2013

Xiao, Yingcai (Ed.): Proceedings of the IADIS International Conference Computer Graphics, Visualization, Computer Vision and Image Processing : CGVCVIP 2013. IADIS Press, 2013, pp. 91-98

IADIS International Conference Computer Graphics, Visualization, Computer Vision and Image Processing (CGVCVIP) <2013, Prague, Czech Republic>

In this paper we present a set of extension techniques to stabilize interactive dynamic graph layout algorithms. It works with different existing Focus & Context methods. We first deal with the initial placement of newly inserted nodes to mitigate acting forces in the layout algorithm. Then, their influence on the existing layout is gradually increased to create a smooth transition between the old and the new layout. To complement this approach we use a look-ahead strategy that integrates additional nodes in the layout to stabilize the layout even more.

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Steiger, Martin; Lücke-Tieke, Hendrik; May, Thorsten; Kuijper, Arjan; Kohlhammer, Jörn

Using Layout Stitching to Create Deterministic Local Graph Layouts

2013

Oliveira, Manuel M. (Ed.) et al.: WSCG 2013. Full Papers. Proceedings : The 21st International Conference in Central Europe on Computer Graphics, Visualization and Computer Vision. Plzen: University of West Bohemia, 2013, pp. 1-9

International Conference in Central Europe on Computer Graphics, Visualization and Computer Vision (WSCG) <21, 2013, Plzen, Czech Republic>

Dynamic graph layouts are often used to position nodes in local views of large graphs. These layouts can be optimized to minimize changes when navigating to other parts of the graph. Dynamic graph layout techniques do not, however, guarantee that a local layout is recognizable when the user visits the same area twice. In this paper we present a method to create stable and deterministic layouts of dynamic views of large graphs. It is based on a well-known panorama-stitching algorithm from the image processing domain. Given a set of overlapping photographs it creates a larger panorama that combines the original images. In analogy to that our algorithm stitches pre-computed layouts of subgraphs to form a larger, single layout. This deterministic approach makes structures and node locations persistent which creates identical visual representations of the graph. This enables the user to recognize previously encountered parts and to decide whether a certain part of a dataset has already been explored before or not.

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Ruppert, Tobias; Bernard, Jürgen; Ulmer, Alex; Kuijper, Arjan; Kohlhammer, Jörn

Visual Access to Optimization Problems in Strategic Environmental Assessment

2013

Bebis, George (Ed.) et al.: Advances in Visual Computing. 9th International Symposium, ISVC 2013 : Proceedings, Part II. Berlin, Heidelberg, New York: Springer, 2013. (Lecture Notes in Computer Science (LNCS) 8034), pp. 361-372

International Symposium on Visual Computing (ISVC) <9, 2013, Rethymnon, Crete, Greece>

The complexity of actual decision making problems especially in the field of policy making is increasing due to conflicting aspects to be considered. Methods from the field of strategic environmental assessment consider environmental, economic, and social impacts caused by political decisions. This makes the analysis of reasonable decisions more complex. Mathematical models like optimization can help to balance conflicting aspects. Although they are not easy to understand, these complex models and the resulting policy options have to be reviewed by the decision makers. In this work we present a visual-interactive interface to an optimization system capable of solving multidimensional decision problems. The interface enables visual access to the complex optimization models, and the analysis of alternative solutions. As a result strategic environmental assessment can be included in the decision making process. An evaluation in the domain of regional energy planning underlines the usability and usefulness of the visual interface.

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Steiger, Martin; May, Thorsten; Davey, James; Kohlhammer, Jörn

Visual Analysis of Expert Systems for Smart Grid Monitoring

2013

Pohl, Margit (Ed.) et al.: EuroVA 2013 : International EuroVis Workshop on Visual Analytics. Goslar: Eurographics Association, 2013, pp. 43-47

International EuroVis Workshop on Visual Analytics (EuroVA) <4, 2013, Leipzig, Germany>

This application paper introduces the combination of an expert system with a visualization system, specifically designed for SmartGrid control rooms. It supports operators in the efficient monitoring of electric grids with a focus on distributed, small-scale power generation. A rule-based expert system filters the stream of a large amount of incoming events, searching for potential problems. A multiple, coordinated view environment provides the required situational awareness for the user and presents the analysis results in a details-on-demand manner. Being a critical infrastructure, the electric grid is highly sensitive and any modification must be well justified. Our visualization system therefore also provides insight into the expert system enabling the user to validate and verify the expert system's analysis process. This provides the required decision support to assist the operator in keeping the grid in stable operating condition.

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Kohlhammer, Jörn; Proff, Dirk U.; Wiener, Andreas

Visual Business Analytics: Effektiver Zugang zu Daten und Informationen

2013

Heidelberg : dpunkt, 2013

Edition TDWI

Business-Intelligence-Lösungen sind für Unternehmen unabdingbar, um Datenmengen in vertretbarer Zeit zu analysieren und daraus resultierend Entscheidungen zu treffen. Dieses Buch zeigt den Weg auf, wie aus Daten mittels Visualisierung entscheidungsrelevante Informationen für den Empfänger werden. Neue, interaktive und grafische Darstellungen tragen dazu bei, dass Entscheider ihr Wissen und ihre Fähigkeiten besser nutzen können, um einen echten Mehrwert für ihr Unternehmen zu generieren. Die Autoren bieten eine fundierte Einführung in das Thema und geben einen praxisnahen Überblick über Visual Business Analytics mit seinen drei Teilgebieten: Information Design, Visual Business Intelligence und Visual Analytics. Sie erläutern anhand vieler Beispiele aus Business-Intelligence-Anwendungsszenarien, welche Darstellungsformen jeweils geeignet sind, um komplexe Zusammenhänge abzubilden, wie Unternehmen Visual Business Analytics erfolgreich nutzen können und welche zukünftigen Möglichkeiten sich durch interaktive Darstellungen ergeben.

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Behrisch, Michael; Davey, James; Simon, Svenja; Schreck, Tobias; Keim, Daniel A.; Kohlhammer, Jörn

Visual Comparison of Orderings and Rankings

2013

Pohl, Margit (Ed.) et al.: EuroVA 2013 : International EuroVis Workshop on Visual Analytics. Goslar: Eurographics Association, 2013, pp. 7-11

International EuroVis Workshop on Visual Analytics (EuroVA) <4, 2013, Leipzig, Germany>

In many data analysis problems, sequentially ordered (or ranked) data occurs that needs to be understood and compared. Ranking information is essential in applications such as multimedia search where retrieval rankings need to be inspected; alignments of gene sequences in bio-molecular applications; or for a more abstract example, considering the permutations of rows and columns for purpose of matrix visualization. In each of these examples, often many different orderings of a given data set are possible. E.g., a search engine may produce, based on different user parameterizations, different rankings. A relevant problem then is to understand the commonalities and differences of a potentially large set of rankings. E.g., finding global or partial orderings in which different ranking or sorting algorithms agree can support the certainty in the respective ranking by the user. We consider the problem of comparing sets of rankings with these questions in mind. We present an approach for a visual comparison of sets of rankings that effectively allows to spot commonalities and differences among rankings. The approach relies on a small-multiple view of glyphs each of which visually contrasts a pair of rankings. The glyph in turn is defined on a radial node-link representation which allows effective perception of agreements and differences in pairs of rankings. We apply our approach on different use cases and demonstrate its effectiveness in spotting patterns of similarity and differences in sets of rankings.

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Burkhardt, Dirk; Nazemi, Kawa; Stab, Christian; Steiger, Martin; Kuijper, Arjan; Kohlhammer, Jörn

Visual Statistics Cockpits for Information Gathering in the Policy-Making Process

2013

Bebis, George (Ed.) et al.: Advances in Visual Computing. 9th International Symposium, ISVC 2013 : Proceedings, Part II. Berlin, Heidelberg, New York: Springer, 2013. (Lecture Notes in Computer Science (LNCS) 8034), pp. 86-97

International Symposium on Visual Computing (ISVC) <9, 2013, Rethymnon, Crete, Greece>

A major step in ICT-driven policy making is information gathering. During this phase, analysts and experts have to deal with a high number of statistical data which they use as a basis to identify problems and find appropriate solutions. This paper introduces a statistical data model to support these analysts and experts. It allows for handling the complexity (i.e. the dimensions) of the data for the visualizations. In particular, it helps to use the same data for two-dimensional, but also multi-dimensional statistics visualizations. Based on this statistic data model we introduce an interactive approach of visual statistics cockpits. This results in highly interactive statistics visualization cockpits that enable both analysts and experts to improve problem assessment and solution finding.

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Nazemi, Kawa; Kohlhammer, Jörn

Visual Variables in Adaptive Visualizations: Presented at the 1st International Workshop on User-Adaptive Visualization (WUAV 2013)

2013

Berkovsky, Shlomo (Ed.) et al.: UMAP 2013 Extended Proceedings : Late-Breaking Results, Project Papers and Workshop Proceedings of the 21st Conference on User Modeling, Adaptation, and Personalization. [cited 20 June 2013] Available from:http://ceur-ws.org/Vol-997, 2013. (CEUR Workshop Proceedings 997), pp. 32-36

International Workshop on User-Adaptive Visualization (WUAV) <1, 2013, Rome, Italy>

Visualizations provide various variables for the adaptation to the usage context and the users. Today's adaptive visualizations make use of various visual variables to order or filter information or visualizations. However, the capabilities of visual variables in context of human information processing and tasks are not comprehensively exploited. This paper discusses the value of the different visual variables providing beneficial and more accurately adapted information visualizations.

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Steiger, Martin; Krämer, Michel; Ruppert, Tobias; Kohlhammer, Jörn

Visualizing Uncertain Underground Information for Urban Management

2013

Xiao, Yingcai (Ed.): Proceedings of the IADIS International Conference Computer Graphics, Visualization, Computer Vision and Image Processing : CGVCVIP 2013. IADIS Press, 2013, pp. 75-82

IADIS International Conference Computer Graphics, Visualization, Computer Vision and Image Processing (CGVCVIP) <2013, Prague, Czech Republic>

In this paper we present approaches for visualizing uncertainty in an application context for urban management. We describe techniques for the visualization of uncertainty and methods for the reduction of the complexity of the visualization to avoid cognitive overload. Uncertainty in both natural and man-made structures in the underground is thus communicated to the user in an appropriate, non-threatening manner. The methods were evaluated during an end-user workshop. The results of this workshop have led to various extensions to the current approach to the visualization of uncertainty in urban management.

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Stab, Christian; Breyer, Matthias; Burkhardt, Dirk; Nazemi, Kawa; Kohlhammer, Jörn

Analytical Semantics Visualization for Discovering Latent Signals in Large Text Collections

2012

Kerren, Andreas (Ed.) et al.: Proceedings of SIGRAD 2012 : Interactive Visual Analysis of Data. Linköping: Linköping University Electronic Press, 2012. (Linköping Electronic Conference Proceedings 81), pp. 83-86

SIGRAD Conference <11, 2012, Växjö, Sweden>

Considering the increasing pressure of competition and high dynamics of markets, the early identification and specific handling of novel developments and trends becomes more and more important for competitive companies. Today, those signals are encoded in large amounts of textual data like competitors' web sites, news articles, scientific publications or blog entries which are freely available in the web. Processing large amounts of textual data is still a tremendous challenge for current business analysts and strategic decision makers. Although current information systems are able to process that amount of data and provide a wide range of information retrieval tools, it is almost impossible to keep track of each thread or opportunity The presented approach combines semantic search and data mining techniques with interactive visualizations for analyzing and identifying weak signals in large text collections. Beside visual summarization tools, it includes an enhanced trend visualization that supports analysts in identifying latent topic-related relations between competitors and their temporal relevance. It includes a graph-based visualization tool for representing relations identified during semantic analysis. The interaction design allows analysts to verify their retrieved hypothesis by exploring the documents that are responsible for the current view.

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Davey, James; Hutter, Marco; May, Thorsten; Kohlhammer, Jörn

Combining Linked Matrix Visualizations with Multi-Dimensional Clustering to Detect Cybercrime: Poster presented at the International Workshop on Visual Analytics (EuroVA)

2012

Darmstadt, 2012

International Workshop on Visual Analytics (EuroVA) <3, 2012, Vienna, Austria>

Our goal is to find a useful multi-dimensional clustering (MDC) of a data set from the network security domain. Algorithms from the Multi-Criteria Decision Analysis (MCDA) domain are used for the calculation of fused similarity matrices, in which the information from several dimensions are combined. However, the results of MCDA algorithms are often difficult to interpret. We present a linked, interactive, matrix-based visualization which simplifies the comparison of clusters and increases the understanding of MCDA results.

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Bernard, Jürgen; Ruppert, Tobias; Scherer, Maximilian; Kohlhammer, Jörn; Schreck, Tobias

Content-Based Layouts for Exploratory Metadata Search in Scientific Research Data

2012

Association for Computing Machinery (ACM): JCDL 2012. Proceedings : 12th ACM/IEEE-CS Joint Conference on Digital Libraries. New York: ACM, 2012, pp. 139-148

ACM/IEEE-CS Joint Conference on Digital Libraries (JCDL) <12, 2012, Washington, DC, USA>

Today's digital libraries (DLs) archive vast amounts of information in the form of text, videos, images, data measurements, etc. User access to DL content can rely on similarity between metadata elements, or similarity between the data itself (content-based similarity). We consider the problem of exploratory search in large DLs of time-oriented data. We propose a novel approach for overview-first exploration of data collections based on user-selected metadata properties. In a 2D layout representing entities of the selected property are laid out based on their similarity with respect to the underlying data content. The display is enhanced by compact summarizations of underlying data elements, and forms the basis for exploratory navigation of users in the data space. The approach is proposed as an interface for visual exploration, leading the user to discover interesting relationships between data items relying on content-based similarity between data items and their respective metadata labels. We apply the method on real data sets from the earth observation community, showing its applicability and usefulness.

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Bernard, Jürgen; Ruppert, Tobias; Scherer, Maximilian; Schreck, Tobias; Kohlhammer, Jörn

Guided Discovery of Interesting Relationships Between Time Series Clusters and Metadata Properties

2012

Lindstaedt, Stefanie (Ed.) et al.: i-KNOW '12. Proceedings : 12th International Conferences on Knowledge Management and Knowledge Technologies. New York: ACM, 2012. (ACM International Conference Proceedings Series 642), pp. 22:1-22:8

International Conference on Knowledge Management and Knowledge Technologies (I-KNOW) <12, 2012, Graz, Austria>

Visual cluster analysis provides valuable tools that help analysts to understand large data sets in terms of representative clusters and relationships thereof. Often, the found clusters are to be understood in context of belonging categorical, numerical or textual metadata which are given for the data elements. While often not part of the clustering process, such metadata play an important role and need to be considered during the interactive cluster exploration process. Traditionally, linked-views allow to relate (or loosely speaking: correlate) clusters with metadata or other properties of the underlying cluster data. Manually inspecting the distribution of metadata for each cluster in a linked-view approach is tedious, especially for large data sets, where a large search problem arises. Fully interactive search for potentially useful or interesting cluster to metadata relationships may constitute a cumbersome and long process. To remedy this problem, we propose a novel approach for guiding users in discovering interesting relationships between clusters and associated metadata. Its goal is to guide the analyst through the potentially huge search space. We focus in our work on metadata of categorical type, which can be summarized for a cluster in form of a histogram. We start from a given visual cluster representation, and compute certain measures of interestingness defined on the distribution of metadata categories for the clusters. These measures are used to automatically score and rank the clusters for potential interestingness regarding the distribution of categorical metadata. Identified interesting relationships are highlighted in the visual cluster representation for easy inspection by the user. We present a system implementing an encompassing, yet extensible, set of interestingness scores for categorical metadata, which can also be extended to numerical metadata. Appropriate visual representations are provided for showing the visual correlations, as well as the calculated ranking scores. Focusing on clusters of time series data, we test our approach on a large real-world data set of time-oriented scientific research data, demonstrating how specific interesting views are automatically identified, supporting the analyst discovering interesting and visually understandable relationships.

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Behrisch, Michael; Davey, James; Schreck, Tobias; Keim, Daniel A.; Kohlhammer, Jörn

Matrix-Based Visual Correlation Analysis on Large Timeseries Data

2012

Santucci, Giuseppe (Ed.) et al.: IEEE Conference on Visual Analytics Science and Technology 2012. Proceedings : VAST 2012. New York: IEEE Press, 2012, pp. 209-210

IEEE Symposium on Visual Analytics Science and Technology (VAST) <7, 2012, Seattle, WA, USA>

In recent years, the quantity of time series data generated in a wide variety of domains grown consistently. Thus, it is difficult for analysts to process and understand this overwhelming amount of data. In the specific case of time series data another problem arises: time series can be highly interrelated. This problem becomes even more challenging when a set of parameters influences the progression of a time series. However, while most visual analysis techniques support the analysis of short time periods, e.g. one day or one week, they fail to visualize large-scale time series, ranging over one year or more. In our approach we present a time series matrix visualization that tackles this problem. Its primary advantages are that it scales to a large number of time series with different start and end points and allows for the visual comparison / correlation analysis of a set of influencing factors. To evaluate our approach, we applied our technique to a real-world data set, showing the impact of local weather conditions on the efficiency of photovoltaic power plants.

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Stab, Christian; Nazemi, Kawa; Breyer, Matthias; Burkhardt, Dirk; Kohlhammer, Jörn

Semantics Visualization for Fostering Search Result Comprehension

2012

Simperl, Elena (Ed.) et al.: The Semantic Web: Research and Applications. Proceedings : ESWC 2012. Berlin, Heidelberg, New York: Springer, 2012. (Lecture Notes in Computer Science (LNCS) 7295), pp. 633-646

Extended Semantic Web Conference (ESWC) <9, 2012, Heraklion, Greece>

Current search engines present search results in an ordered list even if semantic technologies are used for analyzing user queries and the document contents. The semantic information that is used during the search result generation mostly remains hidden from the user although it significantly supports users in understanding why search results are considered as relevant for their individual query. The approach presented in this paper utilizes visualization techniques for offering visual feedback about the reasons the results were retrieved. It represents the semantic neighborhood of search results, the relations between results and query terms as well as the relevance of search results and the semantic interpretation of query terms for fostering search result comprehension. It also provides visual feedback for query enhancement. Therefore, not only the search results are visualized but also further information that occurs during the search processing is used to improve the visual presentation and to offer more transparency in search result generation. The results of an evaluation in a real application scenario show that the presented approach considerably supports users in assessment and decision-making tasks and alleviates information seeking in digital semantic knowledge bases.

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Kohlhammer, Jörn; Nazemi, Kawa; Ruppert, Tobias; Burkhardt, Dirk

Toward Visualization in Policy Modeling

2012

IEEE Computer Graphics and Applications, Vol.32 (2012), 5, pp. 84-89

Graphically Speaking

Information visualization and visual analytics have become widely recognized research fields applied to a variety of domains and data-related challenges. This development's main driver has been the rapidly increasing amount of data that must be dealt with daily. At the same time, citizens, shareholders, and customers expect highly efficient, informed decision-making based on increasingly complex, dynamic, and interdependent data and information. All this applies in many ways to public-policy modeling. As the recent financial crisis has shown, policy making and regulation are highly challenging tasks. The outcomes of policy choices and individual behavior aren't easily predictable in our complex society. Ubiquitous computing, crowd sourcing, and open data, to name just a few examples, are creating masses of data that governments struggle to make sense of for policy modeling. Increasingly, policy makers are perceiving visualization and data analysis as critical to this sense-making process. This article examines the current and future roles of information visualization, semantics visualization, and VA in policy modeling.

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Shum, S. Buckingham; Aberer, K.; Schmidt, A.; Bishop, S.; Lukowicz, P.; Anderson, S.; Charalabidis, Y.; Domingue, J.; Freitas, S. de; Dunwell, I.; Edmonds, B.; Grey, F.; Haklay, M.; Jelasity, M.; Karpistsenko, A.; Kohlhammer, Jörn; Lewis, J.; Pitt, J.; Sumner, R.; Helbing, D.

Towards a Global Participatory Platform: Democratising Open Data, Complexity Science and Collective Intelligence

2012

The European Physical Journal Special Topics, Vol.214 (2012), pp. 109-152

The FuturICT project seeks to use the power of big data, analytic models grounded in complexity science, and the collective intelligence they yield for societal benefit. Accordingly, this paper argues that these new tools should not remain the preserve of restricted government, scientific or corporate élites, but be opened up for societal engagement and critique. To democratise such assets as a public good, requires a sustainable ecosystem enabling different kinds of stakeholder in society, including but not limited to, citizens and advocacy groups, school and university students, policy analysts, scientists, software developers, journalists and politicians. Our working name for envisioning a sociotechnical infrastructure capable of engaging such a wide constituency is the Global Participatory Platform (GPP). We consider what it means to develop a GPP at the different levels of data, models and deliberation, motivating a framework for different stakeholders to find their ecological niches at different levels within the system, serving the functions of (i) sensing the environment in order to pool data, (ii) mining the resulting data for patterns in order to model the past/present/future, and (iii) sharing and contesting possible interpretations of what those models might mean, and in a policy context, possible decisions. A research objective is also to apply the concepts and tools of complexity science and social science to the project's own work. We therefore conceive the global participatory platform as a resilient, epistemic ecosystem, whose design will make it capable of selforganization and adaptation to a dynamic environment, and whose structure and contributions are themselves networks of stakeholders, challenges, issues, ideas and arguments whose structure and dynamics can be modelled and analysed.

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Paolucci, M.; Kossman, D.; Conte, R.; Lukowicz, P.; Argyrakis, P.; Blandford, A.; Bonelli, G.; Anderson, S.; Freitas, S. de; Edmonds, B.; Gilbert, N.; Gross, Markus; Kohlhammer, Jörn; Koumoutsakos, P.; Krause, A.; Linner, B.-O.; Slusallek, P.; Sorkine, O.; Sumner, R.; Helbing, D.

Towards a Living Earth Simulator

2012

The European Physical Journal Special Topics, Vol.214 (2012), pp. 77-108

The Living Earth Simulator (LES) is one of the core components of the FuturICT architecture. It will work as a federation of methods, tools, techniques and facilities supporting all of the FuturICT simulation-related activities to allow and encourage interactive exploration and understanding of societal issues. Society-relevant problems will be targeted by leaning on approaches based on complex systems theories and data science in tight interaction with the other components of FuturICT. The LES will evaluate and provide answers to real-world questions by taking into account multiple scenarios. It will build on present approaches such as agent-based simulation and modeling, multiscale modelling, statistical inference, and data mining, moving beyond disciplinary borders to achieve a new perspective on complex social systems.

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May, Thorsten; Steiger, Martin; Davey, James; Kohlhammer, Jörn

Using Signposts for Navigation in Large Graphs

2012

Computer Graphics Forum, Vol.31 (2012), 3, pp. 985-994

Eurographics Conference on Visualization (EuroVis) <14, 2012, Vienna, Austria>

In this paper we present a new Focus & Context technique for the exploration of large, abstract graphs. Most Focus & Context techniques present context in a visual way. In contrast, our technique uses a symbolic representation: while the focus is a set of visible nodes, labelled signposts provide cues for the context - off-screen regions of the graph - and indicate the direction of the shortest path linking the visible nodes to these regions. We show how the regions are defined and how they are selected dynamically, depending on the visible nodes. To define the set of visible nodes we use an approach developed by van Ham and Perer that dynamically extracts a subgraph based on an initial focal node and a degree-of-interest function. This approach is extended to support multiple focal nodes. With the symbolic visualization, potentially interesting regions of a graph may be represented with a very small visual footprint. We conclude the paper with an initial user study to evaluate the effectiveness of the signposts for navigation tasks.

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Landesberger, Tatiana von; Schreck, Tobias; Fellner, Dieter W.; Kohlhammer, Jörn

Visual Search and Analysis in Complex Information Spaces - Approaches and Research Challenges

2012

Dill, John (Ed.) et al.: Expanding the Frontiers of Visual Analytics and Visualization. Berlin, Heidelberg, New York: Springer, 2012, pp. 45-67

One of the central motivations for visual analytics research is the so-called information overload - implying the challenge for human users in understanding and making decisions in presence of too much information [37]. Visual-interactive systems, integrated with automatic data analysis techniques, can help in making use of such large data sets [35]. Visual Analytics solutions not only need to cope with data volumes that are large on the nominal scale, but also with data that show high complexity. Important characteristics of complex data are that the data items are difficult to compare in a meaningful way based on the raw data. Also, the data items may be composed of different base data types, giving rise to multiple analytical perspectives. Example data types include research data compound of several base data types, multimedia data composed of different media modalities, etc. In this paper, we discuss the role of data complexity for visual analysis and search, and identify implications for designing respective visual analytics applications. We first introduce a data complexity model, and present current example visual analysis approaches based on it, for a selected number of complex data types. We also outline important research challenges for visual search and analysis we deem important.

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Bernard, Jürgen; Ruppert, Tobias; Goroll, Oliver; May, Thorsten; Kohlhammer, Jörn

Visual-Interactive Preprocessing of Time Series Data

2012

Kerren, Andreas (Ed.) et al.: Proceedings of SIGRAD 2012 : Interactive Visual Analysis of Data. Linköping: Linköping University Electronic Press, 2012. (Linköping Electronic Conference Proceedings 81), pp. 39-48

SIGRAD Conference <11, 2012, Växjö, Sweden>

Time series data is an important data type in many different application scenarios. Consequently, there are a great variety of approaches for analyzing time series data. Within these approaches different strategies for cleaning, segmenting, representing, normalizing, comparing, and aggregating time series data can be found. When combining these operations, the time series analysis preprocessing workflow has many degrees of freedom. To define an appropriate preprocessing pipeline, the knowledge of experts coming from the application domain has to be included into the design process. Unfortunately, these experts often cannot estimate the effects of the chosen preprocessing algorithms and their parameterizations on the time series. We introduce a system for the visual-interactive exploitation of the preprocessing parameter space. In contrast to 'black box'-driven approaches designed by computer scientists based on the requirements of domain experts, our system allows these experts to visual-interactively compose time series preprocessing pipelines by themselves. Visual support is provided to choose the right order and parameterization of the preprocessing steps. We demonstrate the usability of our approach with a case study from the digital library domain, in which time-oriented scientific research data has to be preprocessed to realize a visual search and analysis application.

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Bernard, Jürgen; Brase, Jan; Fellner, Dieter W.; Koepler, Oliver; Kohlhammer, Jörn; Ruppert, Tobias; Schreck, Tobias; Sens, Irina

A Visual Digital Library Approach for Time-Oriented Scientific Primary Data

2011

International Journal on Digital Libraries, Vol.11 (2011), 2, pp. 111-123

European Conference on Research and Advanced Technology for Digital Libraries (ECDL) <14, 2010, Glasgow, UK>

Digital Library support for textual and certain types of non-textual documents has significantly advanced over the last years. While Digital Library support implies many aspects along the whole library workflow model, interactive and visual retrieval allowing effective query formulation and result presentation are important functions. Recently, new kinds of non-textual documents which merit Digital Library support, but yet cannot be fully accommodated by existing Digital Library technology, have come into focus. Scientific data, as produced for example, by scientific experimentation, simulation or observation, is such a document type. In this article we report on a concept and first implementation of Digital Library functionality for supporting visual retrieval and exploration in a specific important class of scientific primary data, namely, time-oriented research data. The approach is developed in an interdisciplinary effort by experts from the library, natural sciences, and visual analytics communities. In addition to presenting the concept and to discussing relevant challenges, we present results from a first implementation of our approach as applied on a real-world scientific primary data set. We also report from initial user feedback obtained during discussions with domain experts from the earth observation sciences, indicating the usefulness of our approach.

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May, Thorsten; Bannach, Andreas; Davey, James; Ruppert, Tobias; Kohlhammer, Jörn

Guiding Feature Subset Selection with an Interactive Visualization

2011

Miksch, Silvia (Ed.) et al.: IEEE Conference on Visual Analytics Science and Technology 2011. Proceedings : VAST 2011. New York: IEEE Press, 2011, pp. 111-120

IEEE Symposium on Visual Analytics Science and Technology (VAST) <6, 2011, Providence, RI, USA>

We propose a method for the semi-automated refinement of the results of feature subset selection algorithms. Feature subset selection is a preliminary step in data analysis which identifies the most useful subset of features (columns) in a data table. So-called filter techniques use statistical ranking measures for the correlation of features. Usually a measure is applied to all entities (rows) of a data table. However, the differing contributions of subsets of data entities are masked by statistical aggregation. Feature and entity subset selection are, thus, highly interdependent. Due to the difficulty in visualizing a high-dimensional data table, most feature subset selection algorithms are applied as a black box at the outset of an analysis. Our visualization technique, SmartStripes, allows users to step into the feature subset selection process. It enables the investigation of dependencies and interdependencies between different feature and entity subsets. A user may even choose to control the iterations manually, taking into account the ranking measures, the contributions of different entity subsets, as well as the semantics of the features.

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Kohlhammer, Jörn; Keim, Daniel A.; Pohl, Margit; Santucci, Giuseppe; Andrienko, Gennady

Solving Problems with Visual Analytics

2011

Procedia Computer Science [online], Vol.7 (2011), pp. 117- 120

Proceedings of the 2nd European Future Technologies Conference and Exhibition (FET) <5 ,2011, Budapest, Hungary>

Visual analytics is an emerging research discipline aiming at making the best possible use of huge information loads in a wide variety of applications by appropriately combining the strengths of intelligent automatic data analysis with the visual perception and analysis capabilities of the human user. The major goal of visual analytics is the integration of these disciplines into visual analytics to acquire well-established and agreed upon concepts and theories, combining scientific breakthroughs in a single discipline to have a potential impact on visual analytics and vice versa. In a session at FET11, the leaders of the thematic working groups of the recently finalised FET Open coordination action VisMaster CA presented the scientific challenges that were identified in the visual analytics research roadmap, and the connection between the various disciplines and the broader vision of visual analytics. This article contains excerpts from this research roadmap to motivate further research in this direction within FET. © Selection and peer-review under responsibility of FET11 conference organizers and published by Elsevier B.V.

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Krämer, Michel; Dummer, Martin; Ruppert, Tobias; Kohlhammer, Jörn

Tackling Uncertainty in Combined Visualizations of Underground Information and 3D City Models

2011

HafenCity University, Hamburg: GeoViz Hamburg 2011 Workshop : Linking Geovisualization with Spatial Analysis and Modeling [online]. [cited 4 April 2011] Available from: http://www.geomatik-hamburg.de/geoviz/program.html, 2011, 2 p.

GeoViz Workshop <2, 2011, Hamburg, Germany>

Cities are under constant development. They are characterized not only by their surface constructions like buildings and traffic infrastructure, but also by their underground structures. Besides human-created lifelines, tunnels and quarries, there are also diverse geological formations. Underground information contains a lot of uncertainty by nature, because measurements provide information along drilling lines only. Additionally, man-made structures are often hardly documented. In this paper we will present ways to visualize such uncertainty in combination with exact surface structures from 3D city models in order to assist stakeholders in making decisions. We will evaluate existing techniques and describe the requirements imposed on uncertainty visualization.

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Landesberger, Tatiana von; Kuijper, Arjan; Schreck, Tobias; Kohlhammer, Jörn; van Wijk, Jarke; Fekete, Jean-Daniel; Fellner, Dieter W.

Visual Analysis of Large Graphs: State-of-the-Art and Future Research Challenges

2011

Computer Graphics Forum, Vol.30 (2011), 6, pp. 1719-1749

The analysis of large graphs plays a prominent role in various fields of research and is relevant in many important application areas. Effective visual analysis of graphs requires appropriate visual presentations in combination with respective user interaction facilities and algorithmic graph analysis methods. How to design appropriate graph analysis systems depends on many factors, including the type of graph describing the data, the analytical task at hand and the applicability of graph analysis methods. The most recent surveys of graph visualization and navigation techniques cover techniques that had been introduced until 2000 or concentrate only on graph layouts published until 2002. Recently, new techniques have been developed covering a broader range of graph types, such as timevarying graphs. Also, in accordance with ever growing amounts of graph-structured data becoming available, the inclusion of algorithmic graph analysis and interaction techniques becomes increasingly important. In this State-of-the-Art Report, we survey available techniques for the visual analysis of large graphs. Our review first considers graph visualization techniques according to the type of graphs supported. The visualization techniques form the basis for the presentation of interaction approaches suitable for visual graph exploration. As an important component of visual graph analysis, we discuss various graph algorithmic aspects useful for the different stages of the visual graph analysis process. We also present main open research challenges in this field.

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Dummer, Martin; Krämer, Michel; Ruppert, Tobias; Kohlhammer, Jörn

Visualizing Uncertain Underground Information for Urban Management: Poster presented at the Working with Uncertainty Workshop (IEEE VisWeek 2011)

2011

2011

Working with Uncertainty Workshop <1, 2011, Providence, Rhode Island>

We present approaches for visualizing uncertainty in an application context through techniques for the visualization of uncertainty. We also describe methods for the reduction of the complexity of the visualization to avoid cognitive overload. Uncertainty in both natural and man-made structures under ground is thus communicated to the user in an appropriate, non threatening manner. The methods were evaluated during an end-user workshop of the research project DeepCity3D. The results of this workshop have led to various extensions to our uncertainty visualization approach in urban management

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Knuth, Martin; Kohlhammer, Jörn; Kuijper, Arjan

A Geometry-Shader-Based Adaptive Mesh Refinement Scheme Using Semiuniform Quad/Triangle Patches and Warping

2010

Erleben, Kenny (Ed.) et al.: VRIPHYS 10: 7th Workshop in Virtual Reality Interactions and Physical Simulations. Goslar: Eurographics Association, 2010, pp. 21-29

International Workshop in Virtual Reality Interaction and Physical Simulations (VRIPhys) <7, 2010, Copenhagen, Denmark>

In the field of garment simulation the resolution of the simulation mesh has a direct impact on visual quality. Unfortunately, an increase in mesh resolution introduces a much higher computational cost and potentially causes instability inside the simulation. In addition, it increases the amount of data sent to the renderer for visualisation. Therefore, a GPU-based refinement of the simulated mesh has several advantages, since all additional data is generated immediately before rendering. This allows an increase in visual quality without adding to computational costs for the simulation process or bandwidth necessary for rendering. In this paper we present a view-dependent, adaptive tessellation method designed for the geometry processing stage of modern GPUs. It uses uniform meshes internally, removing the necessity to store external patches. Since we deal with a local refinement scheme, sudden changes in the mesh structure size on adjacent patches may occur incidentally. To reduce this effect as far as possible, we control the triangle density distribution of the refinement process inside a refined triangle patch.

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Ruppert, Tobias; Kohlhammer, Jörn

A Radial Visualization Tool for Depicting Hierarchically Structured Video Content

2010

MacEachren, Alan M. (Ed.) et al.: IEEE Conference on Visual Analytics Science and Technology 2010. Proceedings : VAST 2010. New York: IEEE Press, 2010, pp. 251-252

IEEE Symposium on Visual Analytics Science and Technology (VAST) <5, 2010, Salt Lake City, UT, USA>

The visual analysis of video content is an important research topic due to the huge amount of video data that is generated every day. Annotating this data will become a major problem since the amount of videos further increases. With this work we introduce a system that combines a visualization tool with automatic video segmentation techniques and a characteristic key-frame extraction. A summary of the content of a whole video in one view is realized. Furthermore, the user can interactively browse through the video via our visualization interface to get more detailed information. The system is adapted to two application scenarios and a third application is discussed for future work.

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Bernard, Jürgen; Brase, Jan; Fellner, Dieter W.; Koepler, Oliver; Kohlhammer, Jörn; Ruppert, Tobias; Schreck, Tobias; Sens, Irina

A Visual Digital Library Approach for Time-Oriented Scientific Primary Data

2010

Lalmas, Mounia (Ed.) et al.: Research and Advanced Technology for Digital Libraries : 14th European Conference ECDL. Proceedings. Berlin, Heidelberg, New York: Springer, 2010. (Lecture Notes in Computer Science (LNCS) 6273), pp. 352-363

European Conference on Research and Advanced Technology for Digital Libraries (ECDL) <14, 2010, Glasgow, UK>

Digital Library support for textual and certain types of non-textual documents has significantly advanced over the last years. While Digital Library support implies many aspects along the whole library workflow model, interactive and visual retrieval allowing effective query formulation and result presentation are important functions. Recently, new kinds of non-textual documents which merit Digital Library support, but yet cannot be accommodated by existing Digital Library technology, have come into focus. Scientific primary data, as produced for example, by scientific experimentation, earth observation, or simulation, is such a data type. We report on a concept and first implementation of Digital Library functionality, supporting visual retrieval and exploration in a specific important class of scientific primary data, namely, time-oriented data. The approach is developed in an interdisciplinary effort by experts from the library, natural sciences, and visual analytics communities. In addition to presenting the concept and discussing relevant challenges, we present results from a first implementation of our approach as applied on a real-world scientific primary data set.

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May, Thorsten; Davey, James; Kohlhammer, Jörn

Combining Details of the Chi-Square Goodness-of-Fit Test with Multivariate Data Visualization

2010

Kohlhammer, Jörn (Ed.) et al.: EuroVAST 2010 : International Symposium on Visual Analytics Science and Technology. Goslar: Eurographics Association, 2010, pp. 45-50

International Symposium on Visual Analytics Science and Technology (EuroVAST) <1, 2010, Bordeaux, France>

In this work, we combine KVMaps, a visualization technique presented in [May07] for the visualization of statistical aggregations in multivariate contingency tables, with the measures used for the statistical Chi-Square goodness-of-fit test. Goodness-of-fit tests are used to check whether a given distribution of values matches an expected distribution. A single test statistic is calculated to represent the deviation of the complete dataset. By visualizing the deviations for all entries in the contingency table, it is possible to identify the patterns in the distribution of data items, which contribute most to the overall deviation of the dataset. We present two use cases to illustrate how the information about the patterns can be used.

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Krämer, Michel; Ruppert, Tobias; Klien, Eva; Kohlhammer, Jörn

DeepCity3D: Integration von 3D-Stadtmodellen und Untergrundinformationen

2010

Zipf, Alexander (Ed.) et al.: Geoinformatik 2010. Konferenzband : "Die Welt im Netz". Heidelberg: Akademische Verlagsgesellschaft Aka, 2010, pp. 72-80

Geoinformatik-Tagung <2010, Kiel, Germany>

Modern cities are under constant development. They are characterized not only by their surface constructions like buildings and traffic infrastructure, but also by their underground structures. Besides human-created lifelines, tunnels and quarries, there are also diverse geological formations. All this information is important for a sustainable urban planning and utility management. The DeepCity3D project therefore aims to develop application-adaptive 3D visualization tools that integrate underground data and city models (provided in standardized formats) with advanced functionality to support decision making for stakeholders involved in urban planning, construction companies, insurance companies, architecture, or environmental protection.

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Knuth, Martin; Kohlhammer, Jörn; Kuijper, Arjan

Embedding Hierachical Deformation within a Realtime Scene Graph: A Simple Approach for Embedding GPU-based Realtime Deformations using Trilinear Transformations Embedded in a Scene Graph

2010

Institute for Systems and Technologies of Information, Control and Communication (INSTICC): VISIGRAPP 2010. Proceedings : International Joint Conference on Computer Vision, Imaging and Computer Graphics Theory and Applications. INSTICC Press, 2010, pp. 246-253

International Conference on Computer Graphics Theory and Applications (GRAPP) <5, 2010, Angers, France>

Scene graphs are widely used as a description of spatial relations between objects in a scene. Current scene graphs use linear transformations for this purpose. This limits the relation of two objects in the hierarchy to simple transformations like sheer, translation, rotation and scaling. In contrast to this, we want to represent and control deformations that result from propagating the dynamics of objects to deformable attached objects. Our solution is to replace the linear 4x4 matrix-based transformation of a scene graph by a more generic trilinear transformation. The linear transformation allows the composition of the transformation hierarchy into one transformation. Our approach additionally allows the handling of deformations on the same level. Building on this concept we present a system capable of real-time rendering. The computations of the applied deformations of the scene graph are performed in real-time on the GPU. We allow the approximation of arbitrary nonlinear transformations and deformations by utilising grids of trilinear transformations in our system. As an application we show geometric attachments on deformable objects and their deformation on a scene graph level.

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Kohlhammer, Jörn; Keim, Daniel A.

EuroVAST 2010: International Symposium on Visual Analytics Science and Technology

2010

Goslar : Eurographics Association, 2010

International Symposium on Visual Analytics Science and Technology (EuroVAST) <1, 2010, Bordeaux, France>

EuroVAST 2010 is the first international symposium on visual analytics science and technology held in Europe. The goal of the symposium is to promote and advance the combination and integration of visualization and analytics methods for the purpose of problem solving in a variety of application domains (engineering, business, public policy, medicine, security, etc). Visual Analytics is the science of analytical reasoning supported by the interactive visual interfaces, which requires interdisciplinary science integrating techniques from visualization and computer graphics, statistics and mathematics, data management and knowledge representation, data analysis and machine learning, cognitive and perceptual sciences, and more.

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Kohlhammer, Jörn; Ruppert, Tobias; Mansmann, Florian; Keim, Daniel A.

Information Visualisation and Visual Analytics for Governance and Policy Modelling

2010

European Commission: Future Research on ICT for Governance and Policy Modelling : Crossroad - A Participative Roadmap for ICT Research in Electronic Governance and Policy Modelling. [cited 01 August 2012] Available from: http://crossroad.epu.ntua.gr/public-materia/contributions/, 2010, 8 p.

Gap Analyses & Roadmap Validation Workshop <2010, Samos, Greece>

Professionals involved in governance and policy modelling have seen a dramatic increase in the volume of potentially relevant data. As in many other knowledge-based fields today, policy makers face the problem of an information overload. Putting data from sources as diverse as blogs, online opinion polls and government reports to effective use is a task which requires new tools for their analysis and visualisation. In this paper, we introduce the research field known as Visual Analytics and we argue that it can help policy makers integrate large amounts of heterogeneous data into their decisionmaking processes. In so doing, Visual Analytics has the potential to increase not only the relevance, but also the legitimacy of policy decisions. In addition, policy modelling could provide the Visual Analytics community with new research challenges.

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Keim, Daniel A.; Kohlhammer, Jörn; Mansmann, Florian; May, Thorsten; Wanner, Franz

Introduction

2010

Keim, Daniel A. (Ed.) et al.: Mastering the Information Age. Solving Problems with Visual Analytics. Goslar: Eurographics Association, 2010, pp. 1-6

Raw data has no value in itself, only the extracted information has value. Time and money are wasted and opportunities are lost. Success depends on availability of the right information. Visual analytics aims at making data and information processing transparent. Visual analytics combines the strengths of humans and computers.

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Keim, Daniel A.; Kohlhammer, Jörn; Ellis, Geoffrey; Mannsmann, Florian

Mastering the Information Age. Solving Problems with Visual Analytics

2010

Goslar : Eurographics Association, 2010

This book is the result of a community effort of the partners of the VisMaster Coordinated Action funded by the European Union. The overarching aim of VisMaster was to create a research roadmap that outlines the current state of visual analytics across many disciplines, and to describe the next steps that have to be taken to foster a strong visual analytics community, thus enabling the development of advanced visual analytic applications.

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Ellis, Geoffrey; Keim, Daniel A.; Kohlhammer, Jörn

Recommendations

2010

Keim, Daniel A. (Ed.) et al.: Mastering the Information Age. Solving Problems with Visual Analytics. Goslar: Eurographics Association, 2010, pp. 145-153

This chapter summarises the challenges according to what we believe to be the main entities of visual analytics and then consolidates the recommendations presented in the individual chapters into higher level recommendations for enabling successful visual analytics research. The challenges and recommendations highlight the interdisciplinary nature of visual analytics and the importance of working together. While many initiatives have been started in di erent countries including many EU member states, only under a worldwide and EU-wide umbrella can significant overlap be avoided, and continued strong collaboration between the research groups be fostered.

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Landesberger, Tatiana von; Kuijper, Arjan; Schreck, Tobias; Kohlhammer, Jörn; van Wijk, Jarke; Fekete, Jean-Daniel; Fellner, Dieter W.

Visual Analysis of Large Graphs

2010

Hauser, Helwig (Ed.) et al.: Eurographics 2010. State of the Art Reports (STARs), pp. 113-136

Eurographics <31, 2010, Norrköping, Sweden>

The analysis of large graphs plays a prominent role in various fields of research and is relevant in many important application areas. Effective visual analysis of graphs requires appropriate visual presentations in combination with respective user interaction facilities and algorithmic graph analysis methods. How to design appropriate graph analysis systems depends on many factors, including the type of graph describing the data, the analytical task at hand, and the applicability of graph analysis methods. The most recent surveys of graph visualization and navigation techniques were presented by Herman et al. [HMM00] and Diaz [DPS02]. The first work surveyed the main techniques for visualization of hierarchies and graphs in general that had been introduced until 2000. The second work concentrated on graph layouts introduced until 2002. Recently, new techniques have been developed covering a broader range of graph types, such as time-varying graphs. Also, in accordance with ever growing amounts of graph-structured data becoming available, the inclusion of algorithmic graph analysis and interaction techniques becomes increasingly important. In this State-of-the-Art Report, we survey available techniques for the visual analysis of large graphs. Our review firstly considers graph visualization techniques according to the type of graphs supported. The visualization techniques form the basis for the presentation of interaction approaches suitable for visual graph exploration. As an important component of visual graph analysis, we discuss various graph algorithmic aspects useful for the different stages of the visual graph analysis process.

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Keim, Daniel A.; Kohlhammer, Jörn; Mansmann, Florian; May, Thorsten; Wanner, Franz

Visual Analytics

2010

Keim, Daniel A. (Ed.) et al.: Mastering the Information Age. Solving Problems with Visual Analytics. Goslar: Eurographics Association, 2010, pp. 7-18

Visual analytics is not easy to define, due to its multi-disciplinary nature involving multiple processes and the wide variety of application areas. An early definition was "the science of analytical reasoning facilitated by interactive human-machine interfaces". However, based on current practice, a more specific definition would be: "Visual analytics combines automated Visual analytics combines automated analysis with interactive visualisations analysis techniques with interactive visualisations for an effctive understanding, reasoning and decision making on the basis of very large and complex datasets". So, in terms of the goal of visual analytics, we can elaborate on this definition to state that visual analytics is the creation of tools and techniques to enable people to: - Synthesise information and derive insight from massive, dynamic, ambiguous, and often conflicting data. - Detect the expected and discover the unexpected. - Provide timely, defensible, and understandable assessments. - Communicate these assessment effectively for action

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Kohlhammer, Jörn; May, Thorsten; Davey, James; Ruppert, Tobias

Visual Analytics - Verbindung von Analyseverfahren und Visualisierungstechniken

2010

IM - Die Fachzeitschrift für Information Management & Consulting, Vol.25 (2010), 3, pp. 10-17

Visual Analytics bietet eine Möglichkeit, um große Datenmengen besser zu verstehen. Wissen kann damit aus den gesammelten Unternehmensdaten gewonnen werden. Dieses Wissen kann für Unternehmen einen Wettbewerbsvorteil bedeuten. Bisher werden Unternehmenskennzahlen lediglich mithilfe von statistischen Modellen berechnet. Doch der Bezug zwischen den Daten, den Modellen und den Unternehmenszielen bleibt häufig unklar. Wenn die Visualisierung als wesentlicher Bestandteil des Analyseprozesses eingebunden wird, wird das Verständnis von den Modellen sowie auch von den Daten erhöht. Fehler in den zugrundeliegenden Annahmen können früher behoben werden und neu entdeckte Zusammenhänge können zu sicheren, an Fakten und Zielen überprüfbaren Kennzahlen beim Reporting führen.

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Ruppert, Tobias; May, Thorsten; Kohlhammer, Jörn; Schreck, Tobias

Visuelle Analysen des Datensatzes: Wie versteckte Zusammenhänge sichtbar werden

2010

Trepte, Sabine (Ed.) et al.: Allgemeinbildung in Deutschland : Erkenntnisse aus dem SPIEGEL-Studentenpisa-Test. Wiesbaden: VS Verlag, 2010, pp. 87-104

Wenn Wissenschaftler Daten (z.B. des Studentenpisa-Tests des SPIEGEL) analysieren, stellen sie gemeinhin Hypothesen auf und überprüfen diese dann. In diesem Beitrag wird ein anderes Verfahren vorgestellt. Es handelt sich um ein exploratives Vorgehen, das es erlaubt, versteckte Zusammenhänge in großen und komplexen Datensammlungen zu finden. Dazu werden die Daten ohne die Formulierung einer bestimmten Fragestellung mittels interaktiver graphischer Darstellungen untersucht. Der Beitrag erläutert diese Herangehensweise und stellt drei Techniken vor, die für diesen Zweck am Fraunhofer-Institut für Graphische Datenverarbeitung in Darmstadt und an der TU Darmstadt entwickelt worden sind. Die Vielzahl von möglichen Aussagen über einen unbekannten Datensatz wird mit diesen und vergleichbaren Techniken auf jene reduziert, die es wert sind, genauer untersucht zu werden.

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Hoffmann, Marcus; Kohlhammer, Jörn

A Generic Framework for Using Interactive Visualization on Mobile Devices

2009

Tavangarian, Djamshid (Ed.) et al.: Intelligent Interactive Assistance and Mobile Multimedia Computing : International Conference, IMC 2009. Berlin, Heidelberg, New York: Springer, 2009. (Communications in Computer and Information Science 53), p. 131-142

International Conference on Interactive Applications of Mobile Computing (IMC) <2009, Warnemünde, Germany>

The latest mobile devices are capable of displaying graphical content on larger screens and by increased CPU power offer possibilities for new interesting system approaches and technologies especially in the field of 3D visualization. This paper presents a generic framework for remote visualization on such devices. The presented framework focuses on increased portability and flexibility that goes beyond the results of previous work in this research area. On the server side, existing visualization applications can easily be integrated with and connected to mobile devices. On the client side, the utilization of current standard technologies assures a high portability over a variety of different mobile operating systems and devices.

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Knuth, Martin; Kohlhammer, Jörn

A Hybrid Ambient Occlusion Technique for Dynamic Scenes

2009

Chen, Min (Ed.) et al.: WSCG 2009. Communication Papers Proceedings. Plzen: University of West Bohemia, 2009, pp. 1-8

International Conference in Central Europe on Computer Graphics, Visualization and Computer Vision (WSCG) <17, 2009, Plzen, Czech Republic>

In this paper we present a hybrid technique for illuminating a dynamic scene with self shadowing. Our goal is to perform the necessary calculations with real-time or interactive frame rates. The main idea is to split up the self shadowing process into a global and a local part. This separation allows us to choose combinations of completely independent algorithmic approaches. The global part calculates the self shadowing information of the entire scene. Since it has to process the whole scene, it has a high computational cost; however, a coarse approximation can be created in a short time. In contrast the process for the local part deals with fine details, which have local impact on the scene. It only processes a relevant subset of the scene. Finally we present results based on an implementation using a GPU based self shadowing approximation combined with screen space ambient occlusion for solving the local part.

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Hoffmann, Marcus; Kohlhammer, Jörn

An Interactive Remote Visualization System for Mobile Application Access

2009

Hansen, Hans Robert (Ed.) et al.: Business Services: Konzepte, Technologien, Anwendungen Band 1 : 9. Internationale Tagung Wirtschaftsinformatik. Wien: Österreichische Computer Gesellschaft, 2009. (books@ocg.at 246), pp. 641-650

Internationale Tagung Wirtschaftsinformatik (WI) <9, 2009, Vienna, Austria>

This paper introduces a remote visualization approach that enables the visualization of data sets on mobile devices or in web environments. With this approach the necessary computing power can be outsourced to a server environment. The developed system allows the rendering of 2D and 3D graphics on mobile phones or web browsers with high quality independent of the size of the original data set. Compared to known terminal server or other proprietary remote systems our approach offers a very simple way to integrate with a large variety of applications which makes it useful for real-life application scenarios in business processes.

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Stasko, John; van Wijk, Jarke; Kohlhammer, Jörn

IEEE Symposium on Visual Analytics Science and Technology 2009. Proceedings: VAST 2009

2009

New York : IEEE Press, 2009

IEEE Symposium on Visual Analytics Science and Technology (VAST) <4, 2009, Atlantic City, NJ, USA>

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Landesberger, Tatiana von; Voss, Viktor; Kohlhammer, Jörn

Semantic Search and Visualization of Time-Series Data

2009

Pellegrini, Tassilo (Ed.) et al.: Networked Knowledge - Networked Media : Integrating Knowledge Management, New Media Technologies and Semantic Systems. Berlin, Heidelberg, New York: Springer, 2009. (Studies in Computational Intelligence 221), pp. 205-216

In the economic and financial analysis domain a quick access to the right information plays a major role. Using current systems, the search for and presentation of data is very cumbersome. The data, mostly in form of time-series, is stored in various databases. In order to retrieve the searched data, the analysts need to know where to search and sometimes even the structure of the database and its coding. Then it is required to export the data, process the data and create a chart to view the data. This might take time from tens of minutes to hours. In our work we present a first prototype of an integrated search engine that takes as input a natural language query and offers graphic and text output depending on the user task. The system automatically identifies the time-series answers, types of graphical data presentation and shows the results in a web browser and in Excel. The knowledge-based expert system uses domain ontologies for extraction of economic terms in the search queries and specially built data type taxonomy with user task and chart type ontologies for identification of graphic output.

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Kohlhammer, Jörn; May, Thorsten; Hoffmann, Marcus

Visual Analytics for the Strategic Decision Making Process

2009

Amicis, Raffaele de (Ed.) et al.: GeoSpatial Visual Analytics : Geographical Information Processing and Visual Analytics for Environmental Security. Springer Science+Business Media, 2009. (NATO Science for Peace and Security Series C: Environmental Security), pp. 299-310

NATO Advanced Research Workshop on Geographical Information Processing and Visual Analytics for Environmental Security <2009, Trento, Italy>

The collection and storage of huge amounts of data is no longer a challenge by itself. However, rapidly growing data repositories are creating considerable challenges in many application areas. Visualizations that worked well with a few data items now produce confusing or illegible displays. Decision-makers struggle to act based on a severely restricted understanding of the situation. The goal of Visual Analytics is to overcome this information overload and create new opportunities with these large amounts of data and information. The key challenge is to intelligently combine visualization techniques and analytic algorithms, and to enable the human expert to guide the decision making process. This chapter covers interesting and relevant previous work on situation awareness, naturalistic decision making, and decision-centred visualization. These concepts are put into the context of Visual Analytics research and are further illustrated by application examples.

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Schreck, Tobias; Bernard, Jürgen; Landesberger, Tatiana von; Kohlhammer, Jörn

Visual Cluster Analysis of Trajectory Data With Interactive Kohonen Maps

2009

Information Visualization, Vol.8 (2009), 1, pp. 14-29

Visual-interactive cluster analysis provides valuable tools for effectively analyzing large and complex data sets. Due to desirable properties and an inherent predisposition for visualization, the Kohonen Feature Map (or Self-Organizing Map, or SOM) algorithm is among the most popular and widely used visual clustering techniques. However, the unsupervised nature of the algorithm may be disadvantageous in certain applications. Depending on initialization and data characteristics, cluster maps (cluster layouts) may emerge that do not comply with user preferences, expectations, or the application context. Considering SOM-based analysis of trajectory data, we propose a comprehensive visual-interactive monitoring and control framework extending the basic SOM algorithm. The framework implements the general Visual Analytics idea to effectively combine automatic data analysis with human expert supervision. It provides simple, yet effective facilities for visually monitoring and interactively controlling the trajectory clustering process at arbitrary levels of detail. The approach allows the user to leverage existing domain knowledge and user preferences, arriving at improved cluster maps. We apply the framework on a trajectory clustering problem, demonstrating its potential in combining both unsupervised (machine) and supervised (human expert) processing, in producing appropriate cluster results.

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Wilczek, Arkadiusz; Landesberger, Tatiana von (Betreuer); Kohlhammer, Jörn (Betreuer); Suri, Sachindra (Betreuer)

Visualization Concepts for Asset Planning Tools: Application of Usability Methods in Information Visualization

2009

Darmstadt, TU, Diplomarbeit, 2009

This thesis discribes the interplay between usability engineering and information visualization by analyzing the possible intersections between them, conducting an usability evaluation of existing asset planning tools and developing visualization concepts for an asset planning tool using the findings of the thesis.

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Landesberger, Tatiana von; Knuth, Martin; Schreck, Tobias; Kohlhammer, Jörn

Data Quality Visualization for Multivariate Hierarchic Data

2008

IEEE Computer Society: VisWeek 08. Conference Proceedings [DVD-ROM] : VIS - INFOVIS - VAST [DVD-ROM]. Los Alamitos, Calif.: IEEE Computer Society Press, 2008, pp. 108-109

IEEE Information Visualization Conference (INFOVIS) <14, 2008, Columbus, OH, USA>

In many business applications, decision makers often have to base their decisions on large amounts of data from various sources. Often, the quality of this data varies substantially, affecting the degree of certainty the analyst can put into the analyzed data values. The data quality measures may be of qualitative or quantitative nature, and consist of one or many dimensions. In this poster paper, we first present a brief survey of currently available uncertainty visualization techniques. We then present experimental results we obtained with several techniques for visualization of multidimensional data quality information, applied on multivariate hierarchic data used in an economic data analysis scenario.

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Tekusová, Tatiana; Voss, Viktor; Kohlhammer, Jörn

Semantic Search and Visualization of Time-Series Data

2008

Tochtermann, Klaus (Ed.) et al.: I-KNOW '08 and I-MEDIA '08. Proceedings : International Conferences on Knowledge Management and New Media Technology. Graz: Know-Center, 2008. (J.UCS Journal of Universal Computer Science Special Issue), pp. 332-340

International Conference on Knowledge Management (I-KNOW) <8, 2008, Graz, Austria>

In the economic and financial analysis domain a quick access to the right information plays a major role. Using current systems, the search for and presentation of data is very cumbersome. The data, mostly in form of time-series, is stored in various databases. In order to retrieve the searched data, the analysts need to know where to search and sometimes even the structure of the database and its coding. Then it is required to export the data, process the data and create a chart to view the data. This might take time from tens of minutes to hours. In our work we present a first prototype of an integrated search engine that takes as input a natural language query and offers graphic and text output depending on the user task. The system automatically identifies the time-series answers, types of graphical data presentation and shows the results in a web browser and in Excel. The knowledge-based expert system uses domain ontologies for extraction of economic terms in the search queries and specially built data type taxonomy with user task and chart type ontologies for identification of graphic output.

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May, Thorsten; Kohlhammer, Jörn

Towards Closing the Analysis Gap: Visual Generation of Decision Supporting Schemes from Raw Data

2008

Computer Graphics Forum, Vol.27 (2008), 3, pp. 911-918

Eurographics and IEEE VGTC Symposium on Visualization (EuroVis) <10, 2008, Eindhoven, The Netherlands>

The derivation, manipulation and verification of analytical models from raw data is a process which requires a transformation of information across different levels of abstraction. We introduce a concept for the coupling of data classification and interactive visualization in order to make this transformation visible and steerable for the human user. Data classification techniques generate mappings that formally group data items into categories. Interactive visualization includes the user into an iterative refinement process. The user identifies and selects interesting patterns to define these categories. The following step is the transformation of a visible pattern into the formal definition of a classifier. In the last step the classifier is transformed back into a pattern that is blended with the original data in the same visual display. Our approach allows in intuitive assessment of a formal classifier and its model, the detection of outliers and the handling of noisy data using visual pattern-matching. We instantiated the concept using decision trees for classification and KVMaps as the visualization technique. The generation of a classifier from visual patterns and its verification is transformed from a cognitive to a mostly pre-cognitive task.

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Tekusová, Tatiana; Kohlhammer, Jörn

Visual Analysis and Exploration of Complex Corporate Shareholder Networks

2008

The International Society for Optical Engineering (SPIE): Electronic Imaging 2008. Proceedings CD-ROM : SPIE Proceedings Volumes 6803-6822. Bellingham: SPIE Press, 2008. (Proceedings of SPIE CDS203), Proc. of SPIE 6809, 10 p.

SPIE Conference on Visualization and Data Analysis (VDA) <2008, San Jose, California, USA>

The analysis of large corporate shareholder network structures is an important task in corporate governance, in financing, and in financial investment domains. In a modern economy, large structures of cross-corporation, cross-border shareholder relationships exist, forming complex networks. These networks are often difficult to analyze with traditional approaches. An efficient visualization of the networks helps to reveal the interdependent shareholding formations and the controlling patterns. In this paper, we propose an effective visualization tool that supports the financial analyst in understanding complex shareholding networks. We develop an interactive visual analysis system by combining state-oft he- art visualization technologies with economic analysis methods. Our system is capable to reveal patterns in large corporate shareholder networks, allows the visual identification of the ultimate shareholders, and supports the visual analysis of integrated cash flow and control rights. We apply our system on an extensive real-world database of shareholder relationships, showing its usefulness for effective visual analysis.

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Keim, Daniel A.; Andrienko, Gennady; Fekete, Jean-Daniel; Görg, Carsten; Kohlhammer, Jörn; Melançon, Guy

Visual Analytics: Definition, Process, and Challenges

2008

Kerren, A. (Ed.) et al.: Information Visualization : Human-Centered Issues and Perspectives. Berlin, Heidelberg, New York: Springer, 2008. (Lecture Notes in Computer Science (LNCS) 4950), pp. 154-175

We are living in a world which faces a rapidly increasing amount of data to be dealt with on a daily basis. In the last decade, the steady improvement of data storage devices and means to create and collect data along the way influenced our way of dealing with information: Most of the time, data is stored without filtering and refinement for later use. Virtually every branch of industry or business, and any political or personal activity nowadays generate vast amounts of data. Making matters worse, the possibilities to collect and store data increase at a faster rate than our ability to use it for making decisions. However, in most applications, raw data has no value in itself; instead we want to extract the information contained in it.

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Kohlhammer, Jörn; Tekusová, Tatiana; Bange, Carsten

Visual Business Intelligence

2008

Is-Report, Vol.12 (2008), 7/8, pp. 20-25

Immens wachsende Datenmengen stellen aktuelle Business-Intelligence-Ansätze und Datenverarbeitungsprozesse vor große Herausforderungen. Visual Business Intelligence bezeichnet die Antwort auf die wachsenden Anforderungen der Benutzer insbesondere im Hinblick auf einen intuitiven, zielführenden und interaktiven Zugang zu großen Mengen an Daten und Informationen. Neue interaktive grafische Darstellungen werden dafür sorgen, dass Entscheider ihr Wissen und ihre Fähigkeiten stärker nutzen können, um diese wachsenden Datenmengen effektiv und effizient auswerten zu können.

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Schreck, Tobias; Bernard, Jürgen; Tekusová, Tatiana; Kohlhammer, Jörn

Visual Cluster Analysis of Trajectory Data With Interactive Kohonen Maps

2008

Ebert, David S. (Ed.) et al.: IEEE Symposium on Visual Analytics Science and Technology 2008. Proceedings : VAST 2008. New York: IEEE Press, 2008, pp. 3-10

IEEE Symposium on Visual Analytics Science and Technology (VAST) <3, 2008, Columbus, OH, USA>

Visual-interactive cluster analysis provides valuable tools for effectively analyzing large and complex data sets. Due to desirable properties and an inherent predisposition for visualization, the Kohonen Feature Map (or Self-Organizing Map, or SOM) algorithm is among the most popular and widely used visual clustering techniques. However, the unsupervised nature of the algorithm may be disadvantageous in certain applications. Depending on initialization and data characteristics, cluster maps (cluster layouts) may emerge that do not comply with user preferences, expectations, or the application context. Considering SOM-based analysis of trajectory data, we propose a comprehensive visual-interactive monitoring and control framework extending the basic SOM algorithm. The framework implements the general Visual Analytics idea to effectively combine automatic data analysis with human expert supervision. It provides simple, yet effective facilities for visually monitoring and interactively controlling the trajectory clustering process at arbitrary levels of detail. The approach allows the user to leverage existing domain knowledge and user preferences, arriving at improved cluster maps. We apply the framework on a trajectory clustering problem, demonstrating its potential in combining both unsupervised (machine) and supervised (human expert) processing, in producing appropriate cluster results.

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May, Thorsten; Kohlhammer, Jörn

Visual Verification of Hypotheses

2008

Bebis, George (Ed.) et al.: Advances in Visual Computing. Proceedings Part II : ISVC 2008. Berlin, Heidelberg, New York: Springer, 2008. (Lecture Notes in Computer Science (LNCS) 5359), pp. 31-42

International Symposium on Visual Computing (ISVC) <4, 2008, Las Vegas, NV, USA>

The analytical derivation of a hypothesis is a process, that requires a transformation of information between raw data and an analytical model. Even though much effort has been spent to support the creation of hypotheses both by algorithmic and visual means, much less research has been done on how the process can be reversed for the verification of existing hypotheses. An evaluation of empirical hypotheses must be grounded in raw data and may require many tedious drill-downs, especially for complex data. We present a concept combining an analytical technique for the representation of hypotheses and their transformation into the data-space. We also show visualization techniques for the formalization of the hypothesis in the analytical space and its visual evaluation in the data space. The evaluation is supported by a visual-matchmaking between original raw data and a modification of this data based upon the assumptions implied by the hypothesis.

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Fellner, Dieter W.; Kamps, Thomas; Kohlhammer, Jörn; Stricker, Anna

Vorsprung durch Wissen

2008

ZWF Zeitschrift für wirtschaftlichen Fabrikbetrieb, Vol.103 (2008), 4, pp. 205-208

Seit über 20 Jahren überlassen die Wissenschaftler des FraunhoferInstituts für Graphische Datenverarbeitung IGD Wissensmanagement nicht dem Zufall. Die Forscher erarbeiten intelligente Suchlösungen und Informationsvisualisierungstechnologien und bieten mit ihren Innovationen vielen Unternehmen und Organisationen die Möglichkeit, auf Anforderungen der heutigen dynamischen Informationsgesellschaft schnell reagieren zu können. Die am Fraunhofer IGD entwickelte Software ConWeaver bietet Unternehmen eine semantische und integrierte Suche über Datenbankgrenzen hinweg. Das Suchsystem extrahiert Unternehmenswissen automatisiert aus heterogenen Datenquellen und repräsentiert es in Form multilingualer, semantischer Wissensnetze. Mit der Datenvisualisierung und Informationsanalyse beschäftigt sich die Visual Analytics-Gruppe des Fraunhofer IGD. Die Wissenschafter entwickeln Echtzeitlösungen für die Simulation und die interaktive Visualisierung großer multidimensionaler Daten- und Informationsmengen.

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Tekusová, Tatiana; Kohlhammer, Jörn

Applying Animation to the Visual Analysis of Financial Time-Dependent Data

2007

Banissi, Ebad (Ed.) et al.: 11th International Conference on Information Visualization. Proceedings : IV 2007. Los Alamitos, Calif.: IEEE Computer Society, 2007, pp. 101-108

IEEE International Conference on Information Visualization (IV) <11, 2007, Zurich, Switzerland>

For decades, financial analysts have strived to use modern data visualization tools to improve the timeliness and quality of their analysis. As the amount of data to be processed increases rapidly and requirements on quality of financial analysis rise, the demand for analysis support systems grows. We present a system for the visual analysis of large amounts of time-dependent data using animation. For each data entity, indicators are presented in a scatter-plot framework, displaying the correlation between them. The design of the glyphs illustrates additional data dimensions. The system uses animation to handle the time-dimension of the data. It offers various features, such as focus, zoom, details on demand and time period selection to support the analysis. Financial indicators are used to demonstrate the usability of the system. The animation proves to be a powerful tool for analysing time-dependent processes in cross-sectional data sets and discovering patterns in the data.

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Tritsch, Bernhard; Kohlhammer, Jörn

Cash Code: Mit kreativer Software zum kommerziellen Erfolg

2007

München : Hanser, 2007

In ihrem Buch zeigen Bernhard Tritsch und Jörn Kohlhammer, wie man mit etwas Engagement aus Code Bares machen kann. Aus ihrer eigenen Berufspraxis heraus haben sie einen Leitfaden zusammengestellt und erklären, welche Aufgaben zu erledigen sind und mit welchen rechtlichen oder bürokratischen Hürden zu rechnen ist. Alle wichtigen Themen werden angesprochen: von Urheberrechtsfragen und Anforderungen an die Dokumentation über die Auswahl der geeigneten Installationsroutine und des geeigneten Lizenzmodells bis hin zu Marketing, Kundengewinnung, Service und Support.

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Khakzar, Karim; Blum, Rainer; Kohlhammer, Jörn; Fuhrmann, Arnulph; Maier, Angela; Maier, Axel

Interactive Product Visualization for an In-store Sales Support System for the Clothing Retail

2007

HCI International 2007. Proceedings and Posters [DVD-ROM] : With 8 further Associated Conferences. Berlin, Heidelberg, New York: Springer, 2007. (Lecture Notes in Computer Science (LNCS)), LNCS 4557, pp. 307-316

Symposium on Human Interface <2007, Beijing, China>

The development of an in-store sales support system that focuses on the "virtual try-on" of clothing is the aim of the research project "IntExMa". Based on sophisticated virtual reality technology, the interactive system provides visualization of made-to-measure shirts in combination with digital customer counterparts. The system is intended for seamless integration into existing processes at the point-of-sale and for the support of the collaborative consultation process between salesperson and customer. This paper describes the various system parts stemming from different research disciplines and their integration under the goal of high usability in an everyday setting.

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Kohlhammer, Jörn; Holweg, Daniel

Mobile Day - Markt der Zukunft abgeklopft

2007

GIS Business, (2007), 1/2, pp. 7-9

Mobile Dienste gelten als einer der Zukunftsmärkte schlechthin. Experten erwarten ein Umsatzwachstum auf bis zu 11 Milliarden Euro im Jahr 2007. Forschungsinstitutionen und Unternehmen arbeiten auf Hochtouren an der Entwicklung neuer Anwendungen. Die Nutzungspotenziale der Geräte als Fremdenführer, Navigationsgerät, Unterhaltungsmedium oder elektronische Geldbörse zeigen den multimedialen Alleskönner - zumindest theoretisch. Praktisch nutzt nur ein verschwindend geringer Anteil der Handybesitzer die mobilen Dienste. Nur neun Prozent rufen mit Ihrem Mobiltelefon E-Mails ab, ganze zwei Prozent nutzen mobile Informationsdienste. Laufen die Entwicklungen also ins Leere? Was müssen Hersteller und Anbieter berücksichtigen, damit etwa mobile Internetdienste bald so populär werden wie es das SMS-Schreiben heute bereits ist? Diese Fragen standen im Mittelpunkt der gemeinsamen Veranstaltung "Mobile Anwendungen der Zukunft" von Fraunhofer-Institut für Graphische Datenverarbeitung und InGeoForum am 14. November 2006 in Darmstadt.

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Schreck, Tobias; Tekusová, Tatiana; Kohlhammer, Jörn; Fellner, Dieter W.

Trajectory-Based Visual Analysis of Large Financial Time Series Data

2007

ACM SIGKDD Explorations Newsletter, Vol.9 (2007), 2, pp. 30-37

Visual Analytics seeks to combine automatic data analysis with visualization and human-computer interaction facilities to solve analysis problems in applications characterized by occurrence of large amounts of complex data. The financial data analysis domain is a promising field for research and application of Visual Analytics technology, as it prototypically involves the analysis of large data volumes in solving complex analysis tasks. We introduce a Visual Analytics system for supporting the analysis of large amounts of financial time-varying indicator data. A system, driven by the idea of extending standard technical chart analysis from one to two-dimensional indicator space, is developed. The system relies on an unsupervised clustering algorithm combined with an appropriately designed movement data visualization technique. Several analytical views on the full market and specific assets are offered for the user to navigate, to explore, and to analyze. The system includes automatic screening of the potentially large visualization space, preselecting possibly interesting candidate data views for presentation to the user. The system is applied to a large data set of time varying 2-D stock market data, demonstrating its effectiveness for visual analysis of financial data. We expect the proposed techniques to be beneficial in other application areas as well.

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Keim, Daniel A.; Kohlhammer, Jörn; May, Thorsten; Thomas, Jim

Event Summary of the Workshop on Visual Analytics

2006

Computers & Graphics, Vol.30 (2006), 2, pp.284-286

The increasing power of computer, simulation and sensor technologies enables us to produce and store data at ever growing rates. Nevertheless, in virtually every application area, data has no value in itself: In very large amounts, data actually hides the important information and makes information more and more difficult to acquire. Decision makers and analysts are often confronted with vast amounts of complex, seemingly inconsistent or incomplete data, which are derived from a number of heterogeneous sources. The strategic effort of Fraunhofer IGD is pursued in collaboration with other national and international experts in this area. The recent Workshop on Visual Analytics was jointly organized with Prof. Keim, University of Konstanz and received endorsement by Jim Thomas, PNNL, who is head of the extensive Visual Analytics efforts in the United States.

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Kohlhammer, Jörn; Schulz, Thorsten

Efficient GIS-based Interaction for Emergency Management

2005

TESI 2005 Conference Proceedings CD-ROM : Training, Education & Simulation International. [Maastricht], 2005, 7 p.

Training, Education & Simulation International (TESI) <2005, Maastricht, Netherlands>

This paper presents a framework for efficient GIS-based visualization, simulation and interaction in the emergency management context. Especially the inclusion of availability, distribution, and comprehensibility of information in emergency situations are preconditions for efficient decision making and emergency response. Time-critical domains such as emergency management demand fast decisions from expert users under stress. Decision-centered visualization (DCV) is an approach to adaptive, interactive visualization at the intersection of knowledge engineering and information visualization that is focused on visualization and simulation in time-critical domains. DCV and the covered graphics- and sketch-based interaction approach are the two building blocks of a comprehensive system concept for time-critical applications like emergency management.

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Jenke, Bert; Kohlhammer, Jörn (Betreuer)

Integration einer GIS-Umgebung in ein entscheidungsunterstützendes System mit 3D-Visualisierung

2005

Wiesbaden, FH, Diplomarbeit, 2005

In dieser Diplomarbeit wurde zur Verbesserung der Visualisierung geopositionierter Informationen das geographische Informationssystem ESRI® ArcGIS® Desktop 9.0 mit der 3D-Analyst® Extension, in das aktuelle DCV-System integriert. Decision-Centered Visualization (DCV) ist ein Ansatz für adaptive und interaktive Visualisierung in zeitkritischen und informationsintensiven Anwendungen. Das Hauptaugenmerk liegt dabei auf dem Hervorheben aufgabenrelevanter Informationen, die zum Situationsbewusstsein eines Benutzers unter Zeitdruck beitragen. In zeitkritischen Anwendungen, wie dem Katastrophenschutz, müssen die verantwortlichen Benutzer Entscheidungen in kürzester Zeit treffen. In solchen Anwendungen ist dabei unter anderem die effektive Visualisierung von Informationen von Bedeutung. Die Benutzeroberfläche des aktuellen DCV-Prototyps besteht aus zwei Darstellungsbereichen (oder Frames), einen für die 2D- und den anderen für die 3D-Darstellung, sowie weitere Informationsfelder von ausgewählten Objekten. Die Schnittstelle zur GIS-Funktionalität wird über die ArcObjects®-Technologie zur Verfügung gestellt. Dabei ersetzt ArcGIS® die bisherige Lösung der Karten- und Terraindarstellung in 2D bzw. 3D. Auf der Benutzeroberfläche von DCV werden die Map Control, die Scene Control und die Toolbar Control eingesetzt, um ArcMap®- und ArcScene®-Dokumente zu laden und zu verarbeiten. Die Toolbar Control bietet dabei das gewohnte Erscheinungsbild und die Funktionalitäten von ArcMap® bzw. ArcScene®. Des Weiteren stehen wichtige GIS-Funktionen wie Rotation, Zoomen oder Auslesen von geographischen Daten zur Verfügung. Durch die Darstellung geographischer Informationen auf der Basis von einzelnen Layern bei ArcGIS® ist die Verwendung für mehrere Anwendungsgebiete gewährleistet, z.B. Stadtkarten als Grundlayer für Anwendungen im Notfallmanagement. Je nach Bedarf können weitere Layer mit benötigten Informationen geladen werden. Layer werden im DCV-System für statische Informationen verwendet. Diese Layer können je nach Situation ein- oder ausgeblendet werden. Dynamische Objekte werden für die temporäre Darstellung in Graphikcontainern hinterlegt. Die Schnittstellen zur GIS-Funktionalität von ESRI® und die zusätzliche DCV-eigene Verknüpfung von Karte und Terrain ermöglicht eine koordinierte Darstellung, mit der es beispielsweise möglich ist, die Kamera des 3D-Terrain automatisch an die Position zu setzen, welche in der 2D-Karte durch den Benutzer angeklickt wurde. Durch die erfolgreiche Integration von ArcGIS® in DCV können somit originalgetreue Karten mit den benötigten geopositionierten Informationen in 2D wie auch in 3D visualisiert werden.

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Kohlhammer, Jörn; Encarnação, José L. (Betreuer)

Knowledge Representation for Decision-Centered Visualization

2005

Herdecke : GCA-Verlag, 2005

Forschung und Wissen - Informatik

Zugl.: Darmstadt, TU, Diss., 2005

Users of information systems in timecritical domains are under pressure to digest and process information that is vital for their task. Too often analysts receive the important information buried within a collection of insignificant data and information. Sorting through such a cluttered display and finding the critical information requires a high level of attention and becomes even more challenging with the increasing amounts of information available. Especially in timecritical domains, the problem of information assessment is replaced by the problem of avoiding the timeintensive efforts to review all the available information. The focus of this dissertation was the combination of knowledge representation, information visualization, and human-centered computing to reduce the probability of such information overload, defining the field of decision-centered visualization (DCV). The DCV approach is unique in how it ties together information visualization and knowledge representation in time-critical and information-intensive environments to support the user's situation awareness. The knowledge representation for DCV as it is defined in this thesis corresponds to the conceptual and architectural requirements of DCV to enable decision- centered applications. The goal of this work was a knowledge representation approach that is user-centered, allows scalable information handling, supports knowledge- based information visualization, flexibly supports various kinds of display and presentation systems, and can be realized in a dynamic network environment - all aspects of information systems typically encountered in time-critical domains like air traffic control. Part of the solution introduced in this work was the scalable combination of domain ontologies and domain databases for human-centered and knowledge-based information visualization. The domain ontology as the knowledge structuring element of the representation is integrated with the scalability advantages of databases, together representing the visualization-relevant aspects of a domain. This thesis extends the current information visualization theory by socalled presentation requirements (PRs). PRs allow the abstract analytical description of information, particularly for the support of situation awareness. By describing entity types, their attributes, and relationships between entity types, knowledge about the information in the domain can be combined with knowledge about the necessary information visualization to users under time pressure. This is enabled by using presentation types and data types for the description of information visualization environments, leaning on and extending the current information visualization models with aspects for time-critical and information-intensive domains. With the help of so-called DCV transformations, this work enables the flexible guidance of various display systems by a DCV system tuning the visualization to the current situation, to the task that the user is working working on, and to the role of the user in the current situation. Depending on the needs of the user and the used display system, filtered and prioritized information can be flexibly mapped to visual structures and presented in an effective and efficient way. The results of this work are most applicable to the area of emergency management and are also applied to the field of visual analytics, an integrated field between data mining and information visualization in the area of very information-intensive domains. Here, the presentation requirements enable the reduction of the complexity of the information on an abstract level based on the provided semantics, before any data instances have to be considered.

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Fuhrmann, Arnulph; Groß, Clemens; Knuth, Martin; Kohlhammer, Jörn

Virtual Prototyping of Garments

2005

ProSTEP iViP Association: ProSTEP iVip Science Days 2005 : Cross-Domain Engineering. Bobingen: Kessler Verlagsdruckerei, 2005, pp. 232-243

ProSTEP iVip Science Days <2, 2005, Darmstadt, Germany>

This paper presents a system for virtual prototyping of garments. The garments are constructed using standard 2D tools for pattern design. We present data structures for representing virtual garments, which are used for creating an interface between the 2D pattern construction and 3D garment simulation. The clothing is visualized three-dimensionally on virtual humans. Our system allows interactive draping and adjustment of the virtual garments. The system creates cost savings by reducing the number of real prototypes and decreasing the time-to-market.

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Schulz, Thorsten; Kohlhammer, Jörn

Efficient Query and Visualization Techniques in Mobile GIS Environments

2004

Villanueva, J.J. (Ed.): Proceedings of the Fourth IASTED International Conference on Visualization, Imaging, and Image Processing. Anaheim: ACTA Press, 2004, pp. 123-128

IASTED International Conference on Visualization, Imaging, and Image Processing <4, 2004, Marbella, Spain>

Continuing advances in communication technologies enable mobile users to access complex functionality like geographic information systems. Extensions to traditional interaction metaphors are needed for visual queries, decision support, and visualization to facilitate better and faster understanding in users accessing geo-spatial information. We focus on two modules of a general mobile GIS software architecture: SketchQuery and decision-centered visualization (DCV). SketchQuery enables users to freely specify graphic- und sketch-based queries in a GIS context, while the DCV approach supports decision making by integrating domain knowledge and knowledge about human situation awareness for effective informaion visualization. Efficient and user-centered interaction with GIS information is vital to the user's performance in mobile environments.

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Kohlhammer, Jörn; Zeltzer, David

Towards a Visualization Architecture for Time-Critical Applications

2004

Jardim Nunes, Nuno (Ed.) et al.: International Conference on Intelligent User Interfaces 2004. Proceedings : IUI 2004. New York: ACM Press, 2004, pp. 271-273

International Conference on Intelligent User Interfaces (IUI) <2004, Funchal, Madeira, Portugal>

Time-critical domains, such as emergency management, demand fast decisions from expert users under stress. Our Decision-Centered Visualization (DCV) system supports decision making by integrating domain knowledge and knowledge about human situation awareness for time-critical visualization. Efficient information presentation is vital for the user's situation awareness and, in consequence, to his or her task performance. We address the problem of efficiently visualizing both existing and incoming information by connecting domain data types and presentation requirements of the domain's tasks.

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Kohlhammer, Jörn; Zeltzer, David

DCV: A Decision-Centered Visualization System for Time-Crititical Applications

2003

IEEE Systems, Man and Cybernetics Society: IEEE International Conference on Systems, Man and Cybernetics 2003. Proceedings : System Security and Assurance. New York: IEEE Press, 2003, pp. 3905-3911

IEEE International Conference on Systems, Man and Cybernetics (SMC) <2003, Washington, D.C, USA>

Users of information systems in time-critical domains are under constant pressure to digest and process information that is vital for their task. Thus, the user needs efficient information visualization that avoids displaying information that is not vital at the moment. Decision-Centered Visualization is an adaptive, interactive visualization system that supports decision making by integrating domain knowledge and knowledge about human decision making with an interactive visualization architecture. An important facet of this system is the representation of the underlying domain knowledge. We will first describe the main modules and the main structures of the knowledge representation of the DCV system. We then describe how DCV uses the represented domain knowledge to guide the information visualization in time-critical applications.

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Zeltzer, David; Kohlhammer, Jörn

Knowledge-Based Interactive Visualization for Time-Critical Decision Making

2003

Callaos, Nagib (Ed.) et al.: 7th World Multiconference on Systemics, Cybernetics and Informatics. Proceedings : Volume VI - Informations Systems, Technologies and Applications: Part I. Orlando, Florida: International Institute of Informatics and Systemics, 2003, pp. 409-414

World Multiconference on Systemics, Cybernetics and Informatics (SCI) <7, 2003, Orlando, FL, USA>

In time-critical domains, such as emergency management or military command and control, users are required to make decisions in highly stressful situations. The Decision-Centered Visualization (DCV) system under development at Fraunhofer CRCG supports decision making by integrating domain knowledge and knowledge about human decision making with an interactive visualization architecture. Naturalistic Decision Making (NDM) models inform the design of the DCV user interface module in order to appropriately supply the decision-maker with the necessary information.

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Ester, Martin; Kohlhammer, Jörn; Kriegel, Hans-Peter

The DC-Tree: A Fully Dynamic Index Structure for Data Warehouses

2000

IEEE Computer Society: 16th International Conference on Data Engineering 2000. Proceedings. Los Alamitos, Calif.: IEEE Computer Society, 2000, pp. 379-388

International Conference on Data Engineering (ICDE) <16, 2000, San Diego, California, USA>

In a data warehouse, updates are typically collected and performed periodically in a batch mode, e.g., over night. This standard approach of bulk incremental updates to data warehouses has some drawbacks. First, the average runtime for a single update is small but the total runtime for the whole batch of updates may become rather large. Second, the contents of the data warehouse is not always up to date. In this paper, we introduce the DC-tree, a fully dynamic index structure for data warehouses modeled as a data cube. This new index structure is designed for applications where the above drawbacks of the bulk update approach are critical. The DC-tree is a hierarchical index structure - similar to the X-tree - exploiting the concept hierarchies typically defined for the dimensions of a data cube. We conducted an extensive experimental performance evaluation using the TPC-D benchmark data. Our results demonstrate that the DC-tree yields a significant speed-up compared to the Xtree and the sequential search when processing general range queries on a data cube.

Jedes Semester (siehe TUCaN):

  • 20-00-0216-se 3D Animation & Visualisierung (Seminar mit Martin Knuth)

Jedes Wintersemester:

  • 20-00-0294-iv Informationsvisualisierung und Visual Analytics (mit Tatiana von Landesberger)

Jedes Sommersemester:

  • 20-00-0268-se Visual Analytics (Seminar mit Tatiana von Landesberger)

Mitglied des redaktionellen Beirats

Promotionsgutachten

  • 2013: Promotion von Cagatay Turkay, Universität Bergen, Norwegen

Konferenz-Organisation

  • 2011-2014: Mitglied des Konferenz-Komitees der IEEE VIS (VisWeek)
  • 2010: Gründung des »International EuroVis Workshop on Visual Analytic (EuroVA)« gemeinsam mit Prof. Daniel Keim, Universität Konstanz
  • 2009: Co-Chair der IEEE VAST (Visual Analytics Science and Technologies)

Programmkomitees

  • 2014: IEEE VAST, I-KNOW
  • 2013: EuroVis, I-KNOW, EuroVA
  • 2012: EuroVis, VizSec, ACM SIGRAD, I-KNOW, EuroVA
  • 2011: EuroVis, VAST, I-KNOW, ISVC, IV
  • 2010: IV, IEEE VAST, I-KNOW, ISVC
  • 2009: ISVC, I-KNOW, VMV
  • 2008: IEEE VAST
  • 2007: Co-Editor Computers&Graphics, vol. 31, no. 3

Reviewer für Journale und Konferenzen

  • 2014: EuroVis, IEEE VAST, I-KNOW
  • 2013: TVCG Journal, C&G Journal, VizSec, I-KNOW, EuroVis, EuroVA
  • 2012: TVCG Journal, ACM TiiS Journal, ACM SIGRAD, VAST, EuroVA, ISVC, I-KNOW
  • 2011: EuroVis, VAST, I-KNOW, ISVC, IV
  • 2010: CG&A Journal, IV, VAST, I-KNOW, ISVC
  • 2009: EuroVis, IV, InfoVis, Vis, TVCG Journal, ISVC, I-KNOW, VMV
  • 2008: CG&A Journal, VAST
  • 2007: C&G Journal, InfoVis, VAST

Gutachter für Research-Proposals

  • National Science Foundation, USA
  • Carl-Zeiss-Stiftung
  • Stiftung Rheinland-Pfalz für Innovation
  • Swiss National Science Foundation (SNSF)
  • Netherlands Organisation for Scientific Research (NWO)

Mitgliedschaften

  • IEEE (Institute of Electrical and Electronics Engineers, Inc.), IEEE Computer Society
  • GI (Gesellschaft für Informatik)