Dill, John (Ed.) et al.: Expanding the Frontiers of Visual Analytics and Visualization. Berlin, Heidelberg, New York: Springer, 2012, 23 p.

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.

NAFEMS Online Magazin, Vol.21 (2012), 1, pp. 70-79

Ein wichtiger Teil des Produktentwicklungszyklus ist die Optimierung der strömungs- oder strukturmechanischen Eigenschaften einer Komponente, die normalerweise in einem iterativen und sehr aufwändigen Prozess stattfindet. Neben der Modifikation, Vereinfachung und des Vernetzens der Bauteilgeometrie, kann die Simulation mitunter Stunden bis Tage dauern. In frühen konzeptionellen Designphasen müssen verschiedene Materialparameter sowie unterschiedliche Geometrien ausprobiert und verglichen werden, um zu einem für das spätere Produkt optimalen Design zu gelangen. Dieser zeitaufwändige Prozess begrenzt deutlich die Anzahl der Möglichkeiten, die analysiert werden können. In dieser Arbeit wird das Framework "Rapid CFD" vorgestellt, das es ermöglicht, schnelle Strömungssimulationen für die frühe konzeptionelle Designphase einzusetzen. Um eine solche Geschwindigkeit zu erreichen, wird die Berechnung und Visualisierung von zweidimensionalen Strömungen in Echtzeit kombiniert. Das ermöglicht die interaktive Modifikation von Parametern und Randbedingungen und damit eine schnelle Analyse und Bewertung von unterschiedlichen Geometrien und eine frühzeitige Optimierung eines Bauteils. Das Framework führt alle Berechnungen auf der Graphikkarte (graphics processing unit - GPU) aus und vermeidet damit das aufwändige Kopieren zwischen CPU- und GPU-Hauptspeicher. Die Berechnungen werden auf einem Standard-Desktop PC ausgeführt, sodass die Simulationsergebnisse im Graphikkartenspeicher bleiben und direkt zur Visualisierung verwendet werden können. Für die Modellierung der Geometrie werden B-Splines verwendet, damit Benutzer lokal die Form durch einzelne Kontrollpunkte modifizieren können. Die Diskretisierung wird ebenfalls auf der GPU ausgeführt. Die Berechnung eines einzelnen Zeitschritts auch für Millionen von Unbekannten wird in Bruchteilen von Sekunden durchgeführt. Die intuitive geometrische Manipulation in Kombination mit der unmittelbaren Visualisierung der Simulationsgrößen wie Druck und Geschwindigkeit ermöglichen die direkte Analyse des Einflusses von Geometrie- und Parameteränderungen. Obwohl diese neuartige Simulationstechnik noch nicht die hohe Präzision konventioneller Simulationen erreicht, ermöglicht diese Technik die Beobachtung von Trends und Tendenzen.

Biometrics enables convenient authentication based on a person's physical or behavioral characteristics. In comparison with knowledge- or token-based methods, it links an identity directly to its owner. Furthermore, it can not be forgotten or handed over easily. As biometric techniques have become more and more efficient and accurate, they are widely used in numerous areas. Among the most common application areas are physical and logical access controls, border control, authentication in banking applications and biometric identification in forensics. In this growing field of biometric applications, concerns about privacy and security cannot be neglected. The advantages of biometrics can revert to the opposite easily. The potential misuse of biometric information is not limited to the endangerment of user privacy, since biometric data potentially contain sensitive information like gender, race, state of health, etc. Different applications can be linked through unique biometric data. Additionally, identity theft is a severe threat to identity management, if revocation and reissuing of biometric references are practically impossible. Therefore, template protection techniques are developed to overcome these drawbacks and limitations of biometrics. Their advantage is the creation of multiple secure references from biometric data. These secure references are supposed to be unlinkable and non-invertible in order to achieve the desired level of security and to fulfill privacy requirements. The existing algorithms can be categorized into transformation-based approaches and biometric cryptosystems. The transformation-based approaches deploy different transformation or randomization functions, while the biometric cryptosystems construct secrets from biometric data. The integration in biometric systems is commonly accepted in research and their feasibility according to the recognition performance is proved. Despite of the success of biometric template protection techniques, their security and privacy properties are investigated only limitedly. This predominant deficiency is addressed in this thesis and a systematic evaluation framework for biometric template protection techniques is proposed and demonstrated: Firstly, three main protection goals are identified based on the review of the requirements on template protection techniques. The identified goals can be summarized as security, privacy protection ability and unlinkability. Furthermore, the definitions of privacy and security are given, which allow to quantify the computational complexity estimating a pre-image of a secure template and to measure the hardness of retrieving biometric data respectively. Secondly, three threat models are identified as important prerequisites for the assessment. Threat models define the information about biometric data, system parameters and functions that can be accessed during the evaluation or an attack. The first threat model, so called naive model, assumes that an adversary has very limited information about a system. In the second threat model, the advanced model, we apply Kerckhoffs' principle and assume that essential details of algorithms as well as properties of biometric data are known. The last threat model assumes that an adversary owns large amount of biometric data and this allows him to exploit inaccuracy of biometric systems. It is called the collision threat model. Finally, a systematic framework for privacy and security assessment is proposed. Before an evaluation process, protection goals and threat models need to be clarified. Based on these, the metrics measuring different protection goals as well as an evaluation process determining the metrics will be developed. Both theoretical evaluation with metrics such as entropy, mutual information and practical evaluation based on individual attacks can be used. The framework for privacy and security assessment is applied on the biometric cryptosystems: fuzzy commitment for 3D face and iris recognition is assessed. I develop my own 3D face recognition algorithm based on the depth distribution of facial sub-surfaces and integrate it in the fuzzy commitment scheme. The iris recognition is based on an open source algorithm using Gabor filter. It is implemented in the fuzzy commitment scheme with the two layer coding method as proposed by Hao et al. Both features, the 3D face features and the iris features, represent local characteristics of the modalities. Thus, strong dependency within these features is observed. The second order dependency tree is applied to describe the distribution of 3D face features. The Markov model is applied to characterize the statistical properties of iris features. Thus, security and privacy of these algorithms can be measured with theoretical metrics. Due to strong feature dependency, the achieved security is much smaller than the secret size, which is the assumed security in a perfect secure case with uniformly identically distributed features. Moreover, the unlinkability is analyzed. The analysis shows that these protected systems are less vulnerable to leakage amplification. However, the secure templates contain much personal identifiable information. We demonstrate the attacks, which can identify a subject by linking auxiliary data stored in his secure templates. Cross matching is assessed with the performance of these attacks. Additionally, the characteristic of iris features is exploited to perform an attack retrieving features from secure templates. The efficiency of the practical attack confirms the result of the theoretical assessment of privacy with conditional entropy. The coding process plays a very important role for the security and privacy properties in the fuzzy commitment scheme. Designing a coding method should not only focus on the improvement of code rate. As shown in this thesis, security and privacy properties can be enhanced significantly by changing the dependency pattern in iris features and 3D face features. Therefore, the coding process should be adapted to properties of the underlying biometric features to increase the security and privacy performance. The security and privacy assessment within this thesis is completed by a comparison of two fuzzy commitment algorithms with the fuzzy vault algorithm for fingerprint recognition. Here, different threat models as well as the corresponding protection goals are considered. The fuzzy vault system has the best performance regarding security and irreversibility of biometric features. However, all of these systems are vulnerable to cross matching. The comparison results show that the proposed evaluation framework provides the fundamental basis for benchmarking different template protection algorithms. The proposed framework is also validated with the existing security analysis on transformation-based approaches. Unlike the analysis on biometric cryptosystems, the security is dependent on the hardness of transformation functions or randomization processes. Therefore, the presented analysis is based on efficiency of different kinds of attacks, which measure different protection goals in the appropriate threat models. The security of these approaches depends on the transformation parameters. The knowledge of these parameters allows generating a pre-image, while it is still hard to estimate the original biometric features practically. However, privacy leakage amplifications are still possible. This thesis defines a systematic evaluation framework, which adheres to essential criteria and requirements of biometric template protection techniques. Its applicability is demonstrated with the analysis of template protection algorithms for different biometric modalities. The assessment presented in this thesis is fundamental for a thorough analysis. Furthermore, it provides provable evidence on security and privacy performance. Therefore, it is the fundamental tool for technical innovation and improvement and helps system designers in selecting a suitable template protection algorithm for their applications and needs. It creates a basis for certification and benchmarking of biometric template protection.

The Visual Computer, Vol.27 (2011), 6-8, pp. 485-494

We present a genetic algorithm for approximating densely sampled curves with uniform cubic B-Splines suitable for Combined B-reps. A feature of this representation is altering the continuity property of the B-Spline at any knot, allowing combining freeform curves and polygonal parts within one representation. Naturally there is a trade-off between different approximation properties like accuracy and the number of control points needed. Our algorithm creates very accurate B-Splines with few control points, as shown in Fig. 1. Since the approximation problem is highly nonlinear, we approach it with genetic methods, leading to better results compared to classical gradient based methods. Parallelization and adapted evolution strategies are used to create results very fast.

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

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.

Dogru, Ali H. (Ed.) et al.: Modern Software Engineering Concepts and Practices : Advanced Approaches. Hershey: IGI Global, 2011, pp. 151-195

The service-oriented architecture has become one of the most popular approaches for distributed business applications. A new trend service ecosystem is merging, where service providers can augment their core services by using business service delivery-related available functionalities like distribution and delivery. The semantic service description of services for the business service delivery will become a bottleneck in the service ecosystem. In this chapter, the Visual Semantic Analysis approach is presented to support semi-automatic modeling of semantic service description by combining machine learning and interactive visualization techniques. Furthermore, two application scenarios from the project THESEUSTEXO (funded by German federal ministry of economics and technology) are presented as evaluation of the Visual Semantic Analysis approach.

A new trend Web service ecosystems for Service-Oriented Architectures (SOAs) and Web services is emerging. Services can be offered and traded like products in these ecosystems. The explicit formalization of services' non-functional parameters, e.g. price plans and legal aspects, as Service Descriptions (SD) is one of the main challenges to establish such Web service ecosystems. The manual modeling of Service Descriptions (SDs) is a tedious and cumbersome task. In this thesis, we introduce the innovative approach Visual Semantic Analysis (VSA) to support semi-automatic modeling of service descriptions in Web service ecosystems. This approach combines the semantic analysis and interactive visualization techniques to support the analysis, modeling, and reanalysis of services in an iterative loop. For example, service providers can analyze first the price plans of the already existing services and extract semantic information from them (e.g. cheapest offers and functionalities). Then they can reuse the extracted semantics to model the price plans of their new services. Afterwards, they can reanalyze the new modeled price plans with the already existing services to check their market competitiveness in Web service ecosystems. The experts from different domains, e.g. service engineers, SD modeling experts, and price plan experts, were interviewed in a study to identify the requirements for the VSA approach. These requirements cover aspects related to the analysis of already exiting services and reuse of the analysis results to model new services. Based on the user requirements, we establish a generic process model for the Visual Semantic Analysis. It defines sub processes and transitions between them. Additionally, the technologies used and the data processed in these sub processes are also described. We present also the formal specification of this generic process model that serves as a basis for the conceptual framework of the VSA. A conceptual framework of the VSA elucidates structure and behavior of the Visual Semantic Analysis System. It specifies also system components of the VSA system and interaction between them. Additionally, we present the external interface of the VSA system for the communication with Web service ecosystems. Finally, we present the results of a user study conducted by means of the VSA system that is developed on the base of the VSA conceptual framework. The results of this user study show that the VSA system leads to strongly significant improvement of the time efficiency and offers better support for the analysis, modeling and reanalysis of service descriptions.

Thulasiraman, Parimala (Ed.) et al.: Proceedings 2011 IEEE International Conference on High Performance Computing and Communications : HPCC 2011. Los Alamitos, Calif.: IEEE Computer Society Conference Publishing Services (CPS), 2011, pp. 78-85

A personal computer can be considered as a one-node heterogeneous cluster that simultaneously processes several application tasks. It can be composed by, for example, asymmetric CPU and GPUs. This way, a high-performance heterogeneous platform is built on a desktop for data intensive engineering calculations. In our perspective, a workload distribution over the Processing Units (PUs) plays a key role in such systems. This issue presents challenges since the cost of a task at a PU is non-deterministic and can be affected by parameters not known a priori. This paper presents a context-aware runtime and tuning system based on a compromise between reducing the execution time of engineering applications - due to appropriate dynamic scheduling - and the cost of computing such scheduling applied on a platform composed of CPU and GPUs. Results obtained in experimental case studies are encouraging and a performance gain of 21.77% was achieved in comparison to the static assignment of all tasks to the GPU.

Verband der Elektrotechnik Elektronik Informationstechnik (VDE): Ambient Assisted Living : 4. Deutscher AAL-Kongress mit Ausstellung. Demographischer Wandel-Assistenzsysteme aus der Forschung in den Markt [CD-ROM]. Berlin u.a.: VDE-Verl., 2011, 10 pp. ; Paper 5.3

Die Verwendung von modernen Interaktionsmethoden und Geräten erlaubte eine natürlichere und intuitive Interaktion. Gegenwärtig haben lediglich die Smartphones und Spielekonsolen großen Absatz, welche eine gestenbasierte Interaktion unterstützen. Dies geht einher, dass solche Geräte nicht nur von technisch versierten Konsumenten gekauft werden. Die Interaktion mit solchen Geräten gestaltet sich so einfach, dass oftmals auch ältere Personen mit diesen spielen oder arbeiten. Insbesondere ältere Personen sind häufig gehandicapt, so haben sie oftmals Probleme kleinere Text zu lesen, wie sie häufig auf Fernbedienungen gedruckt sind. Ebenso neigen sie dazu, schnell überfordert zu sein, so dass gerade größere technische Systeme keine Hilfe sind. Wenn die Geräte mit Gesten steuerbar sind, sind die genannten Probleme oftmals vermeidbar. Um aber eine intuitive und einfache Gesteninteraktion zu ermöglichen, müssen entsprechend verständliche und nachvollziehbare Gesten unterstützt werden. Aus diesem Grund versuchen wir in diesem Paper intuitive Gesten für gängige Interaktionsszenarien an computerbasierten Systemen für den Einsatz in unterstützenden Umgebungen zu identifizieren. Im Rahmen der Evaluation sollen die Probanden hierfür ihre bevorzugten Gesten für die verschiedenen Interaktionsszenarien einbringen. Auf Grundlage der Ergebnisse kann später ein intuitiv bedienbares System, unter Verwendung eines beschleunigungssensorbasierten Geräts, entwickelt werden, mit welchem die Nutzer auf intuitive Weise kommunizieren können.

Verband der Elektrotechnik Elektronik Informationstechnik (VDE): Ambient Assisted Living : 4. Deutscher AAL-Kongress mit Ausstellung. Demographischer Wandel-Assistenzsysteme aus der Forschung in den Markt [CD-ROM]. Berlin u.a.: VDE-Verl., 2011, 10 pp. ; Paper 5.3

Die Verwendung von modernen Interaktionsmethoden und Geräten erlaubte eine natürlichere und intuitive Interaktion. Gegenwärtig haben lediglich die Smartphones und Spielekonsolen großen Absatz, welche eine gestenbasierte Interaktion unterstützen. Dies geht einher, dass solche Geräte nicht nur von technisch versierten Konsumenten gekauft werden. Die Interaktion mit solchen Geräten gestaltet sich so einfach, dass oftmals auch ältere Personen mit diesen spielen oder arbeiten. Insbesondere ältere Personen sind häufig gehandicapt, so haben sie oftmals Probleme kleinere Text zu lesen, wie sie häufig auf Fernbedienungen gedruckt sind. Ebenso neigen sie dazu, schnell überfordert zu sein, so dass gerade größere technische Systeme keine Hilfe sind. Wenn die Geräte mit Gesten steuerbar sind, sind die genannten Probleme oftmals vermeidbar. Um aber eine intuitive und einfache Gesteninteraktion zu ermöglichen, müssen entsprechend verständliche und nachvollziehbare Gesten unterstützt werden. Aus diesem Grund versuchen wir in diesem Paper intuitive Gesten für gängige Interaktionsszenarien an computerbasierten Systemen für den Einsatz in unterstützenden Umgebungen zu identifizieren. Im Rahmen der Evaluation sollen die Probanden hierfür ihre bevorzugten Gesten für die verschiedenen Interaktionsszenarien einbringen. Auf Grundlage der Ergebnisse kann später ein intuitiv bedienbares System, unter Verwendung eines beschleunigungssensorbasierten Geräts, entwickelt werden, mit welchem die Nutzer auf intuitive Weise kommunizieren können.

VAR. Virtual Archaeology Review [online], Vol.2 (2011), 4, pp. 95-103. [cited 30 November 2011] Available from: http://www.varjournal.es/doc/varj02 004 09.pdf

A new technology is on the rise that allows the 3D-reconstruction of Cultural Heritage objects from image sequences taken by ordinary digital cameras. We describe the first experiments we made as early adopters in a community-funded research project whose goal is to develop it into a standard CH technology. The paper describes in detail a step-by-step procedure that can be reproduced using free tools by any CH professional. We also give a critical assessment of the workflow and describe several ideas for developing it further into an automatic procedure for 3D reconstruction from images.

The Fraunhofer Institute for Computer Graphics Research IGD with offices in Darmstadt as well as in Rostock, Singapore, and Graz, the partner institutes at the respective universities, the Interactive Graphics Systems Group of Technische Universität Darmstadt, the Computergraphics and Communication Group of the Institute of Computer Science at Rostock University, Nanyang Technological University (NTU), Singapore, and the Visual Computing Cluster of Excellence of Graz University of Technology, cooperate closely within projects and research and development in the field of Computer Graphics. The "Selected Readings in Computer Graphics 2010" consist of 45 articles selected from a total of 186 scientific publications contributed by all these institutions. All articles previously appeared in various scientific books, journals, conferences and workshops, and are reprinted with permission of the respective copyright holders. The publications had to undergo a thorough review process by internationally leading experts and established technical societies. Therefore, the Selected Readings should give a fairly good and detailed overview of the scientific developments in Computer Graphics in the year 2010. They are published by Professor Dieter W. Fellner, the director of Fraunhofer Institute for Computer Graphics Research IGD in Darmstadt, at the same time professor at the Department of Computer Science at Technische Universität Darmstadt, and professor at the Faculty of Computer Science at Graz University of Technology.

The Fraunhofer Institute for Computer Graphics Research IGD with offices in Darmstadt as well as in Rostock, Singapore, and Graz, the partner institutes at the respective universities, the Interactive Graphics Systems Group of Technische Universität Darmstadt, the Computergraphics and Communication Group of the Institute of Computer Science at Rostock University, Nanyang Technological University (NTU), Singapore, and the Visual Computing Cluster of Excellence of Graz University of Technology, cooperate closely within projects and research and development in the field of Computer Graphics. The "Selected Readings in Computer Graphics 2010" consist of 45 articles selected from a total of 186 scientific publications contributed by all these institutions. All articles previously appeared in various scientific books, journals, conferences and workshops, and are reprinted with permission of the respective copyright holders. The publications had to undergo a thorough review process by internationally leading experts and established technical societies. Therefore, the Selected Readings should give a fairly good and detailed overview of the scientific developments in Computer Graphics in the year 2010. They are published by Professor Dieter W. Fellner, the director of Fraunhofer Institute for Computer Graphics Research IGD in Darmstadt, at the same time professor at the Department of Computer Science at Technische Universität Darmstadt, and professor at the Faculty of Computer Science at Graz University of Technology.

Calude, Cristian S. (Ed.) et al.: Rainbow of Computer Science : Dedicated to Hermann Maurer on the Occasion of His 70th Birthday. Berlin, Heidelberg, New York: Springer, 2011, pp. 200-214

A procedural description of a three-dimensional shape has undeniable advantages over conventional descriptions that are all based on the exhaustive enumeration paradigm. Although it is a true generalization, a procedural description of a given shape class is not always easy to obtain. The main problem is that procedural descriptions are typically Turing-complete, which makes 3D shape design formally (and practically) a programming task. We describe an approach that circumvents this problem, is efficient, extensible, and conceptually simple. We demonstrate the broad applicability with a number of examples from different domains and sketch possible future applications. But we also discuss some practical and theoretical limitations of the generative paradigm.

IEEE Computer Society: XIII Symposium on Virtual Reality : SVR 2011. Los Alamitos, Calif.: IEEE Computer Society Conference Publishing Services (CPS), 2011, pp. 1-8

Over the years, faster hardware - with higher clock rates - has been the usual way to improve computing times in computer graphics. Aside from highly costly parallel solutions only affordable by big industries - like the movie industry -, there was no alternative available to desktop users. Nevertheless, this scenario is dramatically changing with the introduction of more and more parallelism in current desktop PCs. Multi-core CPUs are a common basis in current PCs and the power of modern GPUs - which have been multi-core for a long time now - is getting unveiled to developers. nVidia's CUDA is a powerful weapon to explore GPUs parallelism. Yet, its specific target - nVidia graphic cards only - does not provide any solution to other parallel hardware present. OpenCL is a new royalty-free cross-platform intended to be portable across different hardware manufacturers or even different platforms. In this paper we focus on a comparison of advantages and disadvantages of xPU platforms with OpenCL and CUDA in terms of time efficiency. As an example application we use ray tracing algorithms. Three kinds of ray tracers have to be developed in order to conduct a fair comparison: one is CPU based, while the other two are GPU based - using CUDA and OpenCL, respectively. At the end, a comparison is done between them and results are presented and analyzed showing that the CUDA implementation has the best frame rate, but is very closely followed by the OpenCL implementation. Visually, results are identical, showing the high potential of OpenCL as an alternative for CUDA with identical performance.

Virtual characters offer a great potential as intuitive man-machine interface, because they allow simulating non-verbal communicative behavior as well, which requires the coordinated use of various modalities (e.g., speech and gesture). In this sense, multimodal dialogue systems extend current voice response systems, like for instance known from automated support hotlines, to other modalities. While multimodal dialogue systems are an active research area in artificial intelligence (AI) for over twenty years, in computer graphics (CG) further research is still needed. Hence, in this work two basic problems have been identified. On the one hand, there is a gap between the components of AI and CG, which makes it difficult to provide responsive characters in a manageable manner. On the other hand, embedding virtual agents in full 3D applications, particularly in the context of Mixed Reality, still remains problematic. Therefore, in this work a concept for the presentation component of multimodal dialogue systems has been presented, which can be easily integrated into current frameworks for virtual agents. Basically, it consists of a declarative control layer and a declarative execution layer. While the control layer is mainly used for communication with the AI modules, it also provides a declarative language for describing and flexibly controlling communicative behavior. Core technology components are provided in the execution layer. These include a flexible animation system that is integrated into the X3D standard, components for hair simulation, to represent psycho-physiologically caused skin tone changes such as blushing and the simulation of tears, furthermore methods for the declarative control of the virtual camera, and techniques for the realistic visualization of virtual objects in Mixed Reality scenarios. In addition to simplifying the integration into complex 3D applications, the whole environment can thus also be used by the system as another means of communication.

John, Nigel (Co-Chair) et al.: Eurographics 2011. State of the Art Reports (STARs). Eurographics Association, 2011, pp. 75-100

For many application areas, where a task is most naturally represented by talking or where standard input devices are difficult to use or not available at all, virtual characters can be well suited as an intuitive man-machine-interface due to their inherent ability to simulate verbal as well as nonverbal communicative behavior. This type of interface is made possible with the help of multimodal dialog systems, which extend common speech dialog systems with additional modalities just like in human-human interaction. Multimodal dialog systems consist at least of an auditive and graphical component, and communication is based on speech and nonverbal communication alike. However, employing virtual characters as personal and believable dialog partners in multimodal dialogs entails several challenges, because this requires not only a reliable and consistent motion and dialog behavior but also regarding nonverbal communication and affective components. Besides modeling the "mind" and creating intelligent communication behavior on the encoding side, which is an active field of research in artificial intelligence, the visual representation of a character including its perceivable behavior, from a decoding perspective, such as facial expressions and gestures, belongs to the domain of computer graphics and likewise implicates many open issues concerning natural communication. Therefore, in this report we give a comprehensive overview how to go from communication models to actual animation and rendering.

The efficient reconstruction and artifact-free visualization of surfaces from measured real-world data is an important issue in various applications, such as medical and scientific visualization, quality control, and the media-related industry. The main contribution of this thesis is the development of the first efficient GPU-based reconstruction and visualization methods using trivariate splines, i.e., splines defined on tetrahedral partitions. Our methods show that these models are very well-suited for real-time reconstruction and high-quality visualizations of surfaces from volume data. We create a new quasi-interpolating operator which for the first time solves the problem of finding a globally C¹-smooth quadratic spline approximating data and where no tetrahedra need to be further subdivided. In addition, we devise a new projection method for point sets arising from a sufficiently dense sampling of objects. Compared with existing approaches, high-quality surface triangulations can be generated with guaranteed numerical stability.

Eisert, Peter (Ed.) et al.: VMV 2011 : Vision, Modeling, and Visualization. Goslar: Eurographics Association, 2011, pp. 81-87

Today's super zoom cameras offer a large optical zoom range of over 30x. It is easy to take a wide angle photograph of the scene together with a few zoomed in high resolution crops. Only little work has been done to appropriately display the high resolution photo as an inset. Usually, to hide the resolution transition, alpha blending is used. Visible transition boundaries or ghosting artefacts may result. In this paper we introduce a different, novel approach to overcome these problems. Across the transition, we gradually attenuate the maximum image frequency. We achieve this with a Gaussian blur with an exponentially increasing standard deviation.

Bohn, Christian-Arved (Ed.) et al.: Virtuelle und Erweiterte Realität : 8. Workshop der GI-Fachgruppe VR/AR. Aachen: Shaker, 2011. (Berichte aus der Informatik), 9 p.

We address artifacts at corners in soft edge blend masks for tiled projector arrays. We compare existing and novel modifications of the commonly used weighting function and analyze the first order discontinuities of the resulting blend masks. In practice, e.g. when the projector lamps are not equally bright or with rear projection screens, these discontinuities may lead to visible artifacts. By using first order continuous weighting functions, we achieve significantly smoother results compared to commonly used blend masks.

This thesis covers research on new and alternative ways of interaction with computers. Virtual Reality and multi touch setups are discussed with a focus on three dimensional rendering and photographic applications in the field of Computer Graphics. Virtual Reality (VR) and Virtual Environments (VE) were once thought to be the future interface to computers. However, a lot of problems prevent an everyday use. This work shows solutions to some of the problems and discusses remaining issues. Hardware for Virtual Reality is diverse and many new devices are still being developed. An overview on historic and current devices and VE setups is given and our setups are described. The DAVE, an immersive projection room, and the HEyeWall Graz, a large high resolution display with multi touch input are presented. Available processing power and in some parts rapidly decreasing prices lead to a continuous change of the best choice of hardware. A major influence of this choice is the application. VR and multi touch setups often require sensing or tracking the user, optical tracking being a common choice. Hardware and software of an optical 3D marker tracking and an optical multi touch system are explained. The Davelib, a software framework for rendering 3D models in Virtual Environments is presented. It allows to easily port existing 3D applications to immersive setups with stereoscopic rendering and head tracking. Display calibration and rendering issues that are special to VR setups are explained. User interfaces for navigation and manipulation are described, focusing on interaction techniques for the DAVE and for multi touch screens. Intuitive methods are shown that are easy to learn and use, even for computer illiterates. Exemplary applications demonstrate the potential of immersive and non-immersive setups, showing which applications can most benefit from Virtual Environments. Also, some image processing applications in the area of computational photography are explained, that help to better depict the captured scene.

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.

Wichert, Reiner (Ed.) et al.: Ambient Assisted Living : 4. AAL-Kongress 2011. Berlin: Springer Science+Business Media, 2011. (Advanced Technologies and Societal Change), pp. 75-90

Using modern interaction methods and devices provides a more natural and intuitive interaction. Currently, only mobile phones and game consoles which are supporting such gesture-based interactions have good payment-rates. This comes along, that such devices will bought not only by the traditional technical experienced consumers. The interaction with such devices becomes so easy, that also older people playing or working with them. Especially older people have more handicaps, so for them it is hard to read small text, like they are used as description to buttons on remote controls for televisions. They also become fast overstrained, so that bigger technical systems are no help for them. If it is possible to interact with gestures, all these problems can be avoided. But to allow an intuitive and easy gesture interaction, gestures have to be supported, which are easy to understand. Because of that fact, in this paper we tried to identify intuitive gestures for common interaction scenarios on computer-based systems for uses in ambient assisted environment. In this evaluation, the users should commit their opinion of intuitive gestures for different presented scenarios/tasks. Basing on these results, intuitively useable systems can be developed, so that users are able to communicate with technical systems on more intuitive level with accelerometer-based devices.

Wichert, Reiner (Ed.) et al.: Ambient Assisted Living : 4. AAL-Kongress 2011. Berlin: Springer Science+Business Media, 2011. (Advanced Technologies and Societal Change), pp. 75-90

Using modern interaction methods and devices provides a more natural and intuitive interaction. Currently, only mobile phones and game consoles which are supporting such gesture-based interactions have good payment-rates. This comes along, that such devices will bought not only by the traditional technical experienced consumers. The interaction with such devices becomes so easy, that also older people playing or working with them. Especially older people have more handicaps, so for them it is hard to read small text, like they are used as description to buttons on remote controls for televisions. They also become fast overstrained, so that bigger technical systems are no help for them. If it is possible to interact with gestures, all these problems can be avoided. But to allow an intuitive and easy gesture interaction, gestures have to be supported, which are easy to understand. Because of that fact, in this paper we tried to identify intuitive gestures for common interaction scenarios on computer-based systems for uses in ambient assisted environment. In this evaluation, the users should commit their opinion of intuitive gestures for different presented scenarios/tasks. Basing on these results, intuitively useable systems can be developed, so that users are able to communicate with technical systems on more intuitive level with accelerometer-based devices.

Larsson, Thomas (Ed.) et al.: SIGRAD 2011 : Evaluations of Graphics and Visualization - Efficiency, Usefullness, Accesibility, Usability. Linköping: Linköping University Electronic Press, 2011. (Linköping Electronic Conference Proceedings 65), pp. 83-90

The use of 3D shapes in different domains such as in engineering, entertainment, cultural heritage or medicine, is essential for representing 3D physical reality. Regardless of whether the 3D shapes are representing physically or digitally born objects, meshes are a versatile and common representation for the 3D reality. Nonetheless, the mesh generation process does not always produce qualitative results, thus incomplete, non-orientable or non-manifold meshes frequently are the input for the domain application. The domain application itself also demands special requirements, e.g. an engineering simulation requires a volumetric mesh either tetrahedral or hexahedral, while a cultural heritage color enhancement uses a triangular or quadrangular mesh, or in both cases even hybrid meshes. Moreover, the processes applied on the meshes (e.g. modeling, simulation, visualization) need to support some operations, such as querying neighboring information or enabling dynamic changes of geometry and topology. These operations need to be robust, hence the neighboring information can be consistently updated, during the dynamic changes. Dealing with this mesh diversity usually requires dedicated data structures for performing in the given domain application. This paper compiles the considerations toward designing a data structure for dynamic meshes in a generic and robust manner, despite the type and the quality of the input mesh. These aspects enable a flexible representation of 3D shapes toward general purpose geometry processing for dynamic meshes in 2D and 3D.

International Association for the Engineering Analysis Community (NAFEMS): A World of Engineering Simulation: Industrial Needs, Best Practice, Visions for the Future : NWC 2011. NAFEMS World Congress [Book of Abstracts & CD-ROM]. Glasgow: NAFEMS, 2011, 18 p.

The digital exploration of design variations is a key procedure in the embodiment phase of engineering design, in order to efficiently develop optimal solutions. This procedure requires the combination of modeling and simulation capabilities, enabling the engineer to assess the physical and functional behaviors of the proposed solution. Nowadays, this procedure is performed by means of iterating between designers and analysts with their corresponding tools and demanding reciprocal understanding between them. This is nonetheless a very time consuming activity with the currently available tools and technology, even the advance Computer Aided Design (CAD) systems, which can cope with almost any modeling requirement and which presently provide direct connection (i.e. meshing) to analysis modules for models with limited complexity, cannot deal with the interactive exploration of design variations. Moreover, the promising isogeometric analysis, which aims to simulate 3D NURBS representations also requires special transformations (i.e. meshing), which do not allow for interactive exploration of design variations. On the other side, the Computer Aided Engineering (CAE) systems offering morphing support, are only able to explore restricted variations, since large variations or deformations of the model involves expensive remeshing processes. In order to overcome the above mentioned issues and to enable a fully interactive exploration of design variations within an analysis environment, we enhance the simulating model with a high level representation for interacting with semantic features rather than with single elements, we perform combined morphing techniques with local mesh modification for preserving the stability of the numerical model during large variations, and we decouple the storage of the linear system entries and the sequential matrixvector multiplication for getting the solution, in order to permit the update of local entries of the matrix representing the local mesh modifications without the need of a rebuild of the entire system. Our methodology allows the engineers to independently and interactively explore conceptual design variations without restrictions. Hence, the investigation and understanding of the influence of different design features can easily and fast be evaluated and the development of optimal solutions for the design requirements can closely be fulfilled.

ACM SIGGRAPH: Proceedings Web3D 2011 : 16th International Conference on 3D Web Technology. New York: ACM Press, 2011, pp. 39-44

Rendering volumetric phenomena with believable appearance can add tremendous realism to virtual scenes. We introduce the CommonVolumeShader node, an extension of the X3D standard which has been specifically designed for physically-based rendering of participating media. CommonVolumeShader allows content authors to specify optical properties in a concise and purely declarative way and can accurately capture the appearance of many volumetric phenomena. We demonstrate results with implementations for an interactive ray tracer and a rasterization-based pipeline.

Avis, Nick (Ed.) et al.: Eurographics 2011. Short Papers. Eurographics Association, 2011, pp. 25-28

Monte Carlo estimation of direct lighting is often dominated by visibility queries. If an error is tolerable, the calculations can be sped up by using a simple scalar occlusion factor per light source to attenuate radiance, thus decoupling the expensive estimation of visibility from the comparatively cheap sampling of unshadowed radiance and BRDF. In this paper we analyze the error associated with this approximation and derive an upper bound. We demonstrate in a simple relighting application how our result can be used to reduce noise by introducing a controlled error if a reliable estimate of the visibility is already available.

Laga, Hamid (Ed.) et al.: 3D Object Retrieval 2011 : Eurographics Symposium Proceedings. Goslar: Eurographics Association, 2011. (Eurographics Workshop and Symposia Proceedings Series), pp. 1-8; 125 (Color plate)

"What is the difference between a cup and a door?" These kinds of questions have to be answered in the context of digital libraries. This semantic information, which describes an object on a high, abstract level, is needed in order to provide digital library services such as indexing, mark-up and retrieval. In this paper we present a new approach to encode and to extract such semantic information. We use generative modelling techniques to describe a class of objects: each class is represented by one algorithm; and each object is one set of high-level parameters, which reproduces the object if passed to the algorithm. Furthermore, the algorithm is annotated with semantic information, i.e. a human-readable description of the object class it represents. We use such an object description to recognize objects in real-world data e.g. laser scans. Using an algorithmic object description, we are able to identify 3D subparts, which can be described and generated by the algorithm. Furthermore, we can determine the needed input parameters. In this way, we can classify objects, recognize them semantically and we can determine their parameters (cup's height, radius, etc.).

IEEE Computer Graphics and Applications, Vol.31 (2011), 2, p. 58-66

This tutorial presents probability theory techniques for boosting linear algorithms. The approach is based on statistics and uses educated guesses instead of comprehensive calculations. Because estimates can be calculated in sublinear time, many algorithms can benefit from statistical estimation. Several examples show how to significantly boost linear algorithms without negative effects on their results. These examples involve a Ransac algorithm, an image-processing algorithm, and a geometrical reconstruction. The approach exploits that, in many cases, the amount of information in a dataset increases asymptotically sublinearly if its size or sampling density increases. Conversely, an algorithm with expected sublinear running time can extract the most information.

This thesis "Reconstructive Geometry" presents a new collision detection algorithm, a novel approach to generative modeling, and an innovative shape recognition technique. All these contributions are centred around the questions "how to combine acquisition data with generative model descriptions" and "how to perform this combination efficiently". Acquisition data - such as point clouds and triangle meshes - are created e.g. by a 3D scanner or a photogrammetric process. They can describe a shape's geometry very well, but do not contain any semantic information. With generative descriptions it's the other way round: a procedure describes a rather ideal object and its construction process. This thesis builds a bridge between both types of geometry descriptions and combines them to a semantic unit. An innovative shape recognition technique, presented in this thesis, determines whether a digitized real-world object might have been created by a given generative description, and if so, it identifies the high-level parameters that have been passed to the generative script. Such a generative script is a simple JavaScript function. Using the generative modeling compiler "Euclides" the function can be understood in a mathematical sense; i.e. it can be differentiated with respect to its input parameters, it can be embedded into an objective function, and it can be optimized using standard numerical analysis. This approach offers a wide range of applications for generative modeling techniques; parameters do not have to be set manually - they can be set automatically according to a reasonable objective function. In case of shape recognition, the objective function is distance-based and measures the similarity of two objects. The techniques that are used to efficiently perform this task (space partitioning, hierarchical structures, etc.) are the same in collision detection where the question, whether two objects have distance zero, is answered. To sum up, distance functions and distance calculations are a main part of this thesis along with their application in geometric object descriptions, semantic enrichment, numerical analysis and many more.

Remondino, Fabio (Ed.) et al.: Proceedings of the 4th ISPRS International Workshop 3D-ARCH 2011 : 3D Virtual Reconstruction and Visualization of Complex Architectures [CD-ROM]. (The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XXXVIII-5/W16), 5 p.

The need to analyze and visualize differences of very similar objects arises in many research areas: mesh compression, scan alignment, nominal/actual value comparison, quality management, and surface reconstruction to name a few. In computer graphics, for example, differences of surfaces are used for analyzing mesh processing algorithms such as mesh compression. They are also used to validate reconstruction and fitting results of laser scanned surfaces. As laser scanning has become very important for the acquisition and preservation of artifacts, scanned representations are used for documentation as well as analysis of ancient objects. Detailed mesh comparisons can reveal smallest changes and damages. These analysis and documentation tasks are needed not only in the context of cultural heritage but also in engineering and manufacturing. Differences of surfaces are analyzed to check the quality of productions. Our contribution to this problem is a workflow, which compares a reference / nominal surface with an actual, laser-scanned data set. The reference surface is a procedural model whose accuracy and systematics describe the semantic properties of an object; whereas the laser-scanned object is a real-world data set without any additional semantic information.

The training of technicians in the acquisition of new maintenance and assembly tasks is an important factor in industry. As the complexity of these tasks can be enormous, the training of technicians to acquire the necessary skills to perform them efficiently is a challenging point. However, traditional training programs are usually highly theoretical and it is difficult for the trainees to transfer the acquired theoretical knowledge about the task to the real task conditions, or rather, to the physical performance of the task. In addition, traditional training programs are often expensive in terms of effort and cost. Previous research has shown that Augmented Reality is a powerful technology to support training in the particular context of industrial service procedures, since instructions on how to perform the service tasks can be directly linked to the machine parts to be processed. Various approaches exist, in which the trainee is guided step-by-step through the maintenance task, but these systems act more as guiding systems than as training systems and focus only on the trainees' sensorimotor capabilities. Due to the increasing complexity of maintenance tasks, it is not sufficient to train the technicians' execution of these tasks, but rather to train the underlying skills - sensorimotor and cognitive - that are necessary for an efficient acquisition and performance of new maintenance operations. All these facts lead to the need for efficient training systems for the training of maintenance and assembly skills which accelerate the technicians' learning and acquisition of new maintenance procedures. Furthermore, these systems should improve the adjustment of the training process to new training scenarios and enable the reuse of existing training material that has proven its worth. In this thesis a novel concept and platform for multimodal Augmented Reality-based training of maintenance and assembly skills is presented. This concept includes the identification of necessary sub-skills, the training of the involved skills, and the design of a training program for the training of maintenance and assembly skills. Since procedural skills are considered as the most important skills for maintenance and assembly operations, they are discussed in detail, as well as appropriate methods for improving them. We further show that the application of Augmented Reality technologies and the provision of multimodal feedback -and vibrotactile feedback in particular-have a great potential to enhance skill training in general. As a result, training strategies and specific accelerators for the training of maintenance and assembly skills in general and procedural skills in particular are elaborated. Here, accelerators are concrete methods used to implement the pursued training strategies. Furthermore, a novel concept for displaying location-dependent information in Augmented Reality environments is introduced, which can compensate tracking imprecisions. In this concept, the pointercontent metaphor of annotating documents is transferred to Augmented Reality environments. As a result, Adaptive Visual Aids are defined which consist of a tracking-dependent pointer object and a tracking-independent content object, both providing an adaptable level and type of information. Thus, the guidance level of Augmented Reality overlays in AR-based training applications can be easily controlled. Adaptive Visual Aids can be used to substitute traditional Augmented Reality overlays (i.e. overlays in form of 3D animations), which highly suffer from tracking inaccuracies. The design of the multimodal AR-based training platform proposed in this thesis is not specific for the training of maintenance and assembly skills, but is a general design approach for multimodal training platforms. We further present an implementation of this platform based on the X3D ISO standard which provides features that are useful for the development of Augmented Reality environments. This standard-based implementation increases the sustainability and portability of the platform. The implemented multimodal Augmented Reality-based platform for training of maintenance and assembly skills has been evaluated in industry and compared to traditional training methods. The results show that the developed training platform and the pursued training strategies are very well suited for the training of maintenance and assembly skills and enhance traditional training. With the presented framework we have overcome the problems sketched above. We are cheap in terms of effort and costs for the training of maintenance and assembly skills and we improve its efficiency compared with traditional training.

The Visual Computer, Vol.27 (2011), 6-8, pp. 473-483

We present a physically based interactive simulation technique for de formable objects. Our method models the geometry as well as the displacements using quadratic basis functions in Bernstein-Bézier form on a tetrahedral finite element mesh. The Bernstein-Bézier formulation yields significant advantages compared to approaches using the monomial form. The implementation is simplified, as spatial derivatives and integrals of the displacement field are obtained analytically avoiding the need for numerical evaluations of the elements' stiffness matrices. We introduce a novel traversal accounting for adjacency in order to accelerate the reconstruction of the global matrices. We show that our proposed method can compensate the additional effort introduced by the co-rotational formulation to a large extent. We validate our approach on several models and demonstrate new levels of accuracy and performance in comparison to current state-of-the-art.

International Association for the Engineering Analysis Community (NAFEMS): The Integration of CFD into the Product Development Process : Seminar. Glasgow: NAFEMS, 2011, 9 p.

An important step of the product development is the optimization of the components' physical behavior, which is usually done in a costly iterative process. Besides the modification, simplification, and (re-) meshing of the component's geometry, simulating its behavior can take hours or even days. In the early conceptual design phase, different material properties and shapes need to be tested and compared, in order to optimally design the component. Nonetheless, time consuming simulations limit the realm of possibilities. We have developed a framework for enabling rapid Computational Fluid Dynamics (CFD) for the early conceptual design phase. In order to achieve this, we combine the computation and visualization of 2D fluid flow in real time with the modification of fluid parameters, boundary conditions and geometry. This allows for the rapid assessment and analysis of different shapes and therefore the optimization of the component. Our framework is completely based on graphic processing units (GPUs), i.e., all computations are performed on the GPU avoiding costly memory transfers between graphic hardware and CPU memory. The computations are performed on a single desktop PC, thus the simulation results can reside in GPU memory and can directly be visualized. B-Spline curves are used for modelling the geometry and the user can interactively modify it by means of inserting and moving control points or applying local smooth deformations, with the corresponding rapid update of the discretization on the GPU. Computing one single time step is performed in fractions of a second, even if the fluid flow is modelled with about one million degrees of freedom. The fast geometric manipulation combined with the direct visualization of quantities like velocity or pressure field allows for an immediate feedback of shape or parameter changes. Although fast simulations do not yet achieve the high precision compared to conventional simulations, their results are suitable for analyzing trends.

International Association for the Engineering Analysis Community (NAFEMS): The Integration of CFD into the Product Development Process : Seminar. Glasgow: NAFEMS, 2011, 9 p.

An important step of the product development is the optimization of the components' physical behavior, which is usually done in a costly iterative process. Besides the modification, simplification, and (re-) meshing of the component's geometry, simulating its behavior can take hours or even days. In the early conceptual design phase, different material properties and shapes need to be tested and compared, in order to optimally design the component. Nonetheless, time consuming simulations limit the realm of possibilities. We have developed a framework for enabling rapid Computational Fluid Dynamics (CFD) for the early conceptual design phase. In order to achieve this, we combine the computation and visualization of 2D fluid flow in real time with the modification of fluid parameters, boundary conditions and geometry. This allows for the rapid assessment and analysis of different shapes and therefore the optimization of the component. Our framework is completely based on graphic processing units (GPUs), i.e., all computations are performed on the GPU avoiding costly memory transfers between graphic hardware and CPU memory. The computations are performed on a single desktop PC, thus the simulation results can reside in GPU memory and can directly be visualized. B-Spline curves are used for modelling the geometry and the user can interactively modify it by means of inserting and moving control points or applying local smooth deformations, with the corresponding rapid update of the discretization on the GPU. Computing one single time step is performed in fractions of a second, even if the fluid flow is modelled with about one million degrees of freedom. The fast geometric manipulation combined with the direct visualization of quantities like velocity or pressure field allows for an immediate feedback of shape or parameter changes. Although fast simulations do not yet achieve the high precision compared to conventional simulations, their results are suitable for analyzing trends.

ACM SIGGRAPH: Proceedings Web3D 2010 : 15th International Conference on 3D Web Technology. New York: ACM Press, 2010, pp. 185-193

We present a scalable architecture, which implements and further evolve the HTML/X3D integration model X3DOM introduced in [Behr et al. 2009]. The goal of this model is to integrate and update declarative X3D content directly in the HTML DOM tree. The model was previously presented in a very abstract and generic way by only suggesting implementation strategies. The available opensource x3dom.js architecture provides concrete solutions to the previously open points and extents the generic model if necessary. The outstanding feature of the architecture is to provide a single declarative interface to application developers and at the same time support of various backends through a powerful fallback-model. This fallback-model does not provide a single implementation strategy for the runtime and rendering module but supports different methods transparently. This includes native browser implementations and X3D-plugins as well as a WebGL-based scene-graph, which allows running the content without the need for installing additional plugins on all browsers that support WebGL. The paper furthermore discusses generic aspects of the architecture like encoding and introspection, but also provides details concerning two backends. It shows how the system interfaces with X3D-plugins and WebGL and also discusses implementation specific features and limitations.

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

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.

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. 376-383

The PROBADO project is a research effort to develop and operate advanced Digital Library support for non-textual documents. The main goal is to contribute to all parts of the Digital Library work flow from content acquisition over indexing to search and presentation. While not limited in terms of supported document types, reference support is developed for classical digital music and 3D architectural models. In this paper, we review the overall goals, approaches taken, and lessons learned so far in a highly integrated effort of university researchers and library experts. We address the problem of technology transfer, aspects of repository compilation, and the problem of inter-domain retrieval. The experiences are relevant for other project efforts in the non-textual Digital Library domain.

Mittermaier, Bernhard (Ed.): eLibrary - den Wandel gestalten. Jülich: Forschungszentrum Jülich, 2010. (Schriften des Forschungszentrums Jülich, Reihe Bibliothek / Library 20), pp. 219-233

Das PROBADO Projekt ist ein von der DFG gefördertes Leistungszentrum für Forschungsinformation mit dem Ziel des prototypischen Aufbaus und Betriebs einer verteilten digitalen Bibliothek für heterogene, nicht-textuelle Dokumente. Betrachtet werden in diesem Projekt alle Schritte der bibliothekarischen Verwertungskette vom Bestandsaufbau über semi-automatische Inhaltserschließung, bis hin zu visuellinteraktiver Suche und Präsentation sowie Betriebsaspekten. In diesem Beitrag werden der gewählte Ansatz beschrieben und die bislang im Projekt gemachten praktischen und konzeptionellen Erfahrungen systematisiert und eingeordnet.

Ioannides, Marinos (Ed.) et al.: Digital Heritage. Third International Conference, EuroMed 2010. Berlin, Heidelberg, New York: Springer, 2010. (Lecture Notes in Computer Science (LNCS) 6436), pp. 166-178

Publishing cultural heritage as 3D models with embedded annotations and additional information on the web is still a major challenge. This includes the acquisition of the digital 3D model, the authoring and editing of the additional information to be attached to the digital model as well as publishing it in a suitable format. These steps usually require very expensive hardware and software tools. Especially small museums cannot afford an expensive scanning campaign in order to generate the 3D models from the real artefacts. In this paper we propose an affordable publishing workflow from acquisition of the data to authoring and enriching it with the related metadata and information to finally publish it in a way suitable for access by means of a web browser over the internet. All parts of the workflow are based on open source solutions and free services.

IEEE Computer Society: Proceedings 2010 12th IEEE International Conference on High Performance Computing and Communications : HPCC 2010. Los Alamitos, Calif.: IEEE Computer Society Conference Publishing Services (CPS), 2010, pp. 305-313

GPUs (Graphics Processing Units) have become one of the main co-processors that contributed to desktops towards high performance computing. Together with multi-core CPUs, a powerful heterogeneous execution platform is built for massive calculations. To improve application performance and explore this heterogeneity, a distribution of workload in a balanced way over the PUs (Processing Units) plays an important role for the system. However, this problem faces challenges since the cost of a task at a PU is non-deterministic and can be influenced by several parameters not known a priori, like the problem size domain. We present a comparison of iterative SLE (Systems of Linear Equations) solvers, used in many scientific and engineering applications, over a heterogeneous CPU-GPUs platform and characterize scenarios where the solvers obtain better performances. A new technique to improve memory access on matrix vector multiplication used by SLEs on GPUs is described and compared to standard implementations for CPU and GPUs. Such timing profiling is analyzed and break-even points based on the problem sizes are identified for this implementation, pointing whether our technique is faster to use GPU instead of CPU. Preliminary results show the importance of this study applied to a real-time CFD (Computational Fluid Dynamics) application with geometry modification.

Bentes, Cristiana (Ed.) et al.: SBAC-PADW 2010 : 1st Workshop on Applications for Multi and Many Core Architectures (WAMMCA). Los Alamitos, Calif.: IEEE Computer Society Conference Publishing Services (CPS), 2010, pp. 37-42

GPUs (Graphics Processing Units) have become one of the main co-processors that contributed to desktops towards high performance computing. Together with multicore CPUs and other co-processors, a powerful heterogeneous execution platform is built on a desktop for data intensive calculations. In our perspective, we see the modern desktop as a heterogeneous cluster that can deal with several applications' tasks at the same time. To improve application performance and explore such heterogeneity, a distribution of workload over the asymmetric PUs (Processing Units) plays an important role for the system. However, this problem faces challenges since the cost of a task at a PU is non-deterministic and can be influenced by several parameters not known a priori, like the problem size domain. We present a context-aware architecture that maximizes application performance on such platforms. This approach combines a model for a first scheduling based on an offline performance benchmark with a runtime model that keeps track of tasks' real performance. We carried a demonstration using a CPU-GPU platform for computing iterative SLEs (Systems of Linear Equations) solvers using the number of unknowns as the main parameter for assignment decision. We achieved a gain of 38.3% in comparison to the static assignment of all tasks to the GPU (which is done by current programming models, such as OpenCL and CUDA for Nvidia).

IEEE Computer Society: 2010 IEEE International Symposium on Parallel & Distributed Processing, Workshops and Phd Forum : IPDPSW. New York: IEEE Computer Society Press, 2010, 4 p.

High-performance platforms are required by applications that use massive calculations. Actually, desktop accelerators (like the GPUs) form a powerful heterogeneous platform in conjunction with multi-core CPUs. To improve application performance on these hybrid platforms, load-balancing plays an important role to distribute workload. However, such scheduling problem faces challenges since the cost of a task at a Processing Unit (PU) is non-deterministic and depends on parameters that cannot be known a priori, like input data, online creation of tasks, scenario changing, etc. Therefore, self-adaptive computing is a potential paradigm as it can provide flexibility to explore computational resources and improve performance on different execution scenarios. This paper presents an ongoing PhD research focused on a dynamic and reconfigurable scheduling strategy based on timing profiling for desktop accelerators. Preliminary results analyze the performance of solvers for SLEs (Systems of Linear Equations) over a hybrid CPU and multi-GPU platform applied to a CFD (Computational Fluid Dynamics) application. The decision of choosing the best solver as well as its scheduling must be performed dynamically considering online parameters in order to achieve a better application performance.

ACM SIGGRAPH: Proceedings Web3D 2010 : 15th International Conference on 3D Web Technology. New York: ACM Press, 2010, pp. 63-71

3D is useful in many real-world applications beyond computer games. The efficiency of communication is greatly enhanced by combining interlinked verbal descriptions with 3D content. However, there is a wide gap between the great demand for 3D content and the inconvenience and cost of delivering it. We propose using PDF, which is extremely well supported by standard content production workflows. Producing PDF with embedded 3D is currently not an easy task. As a solution to the problem we offer a freely available tool that makes embedding 3D in PDF documents an easy to use technology. Our solution is very flexible, extensible, and can be easily integrated with existing document workflow technology.

Herrington, Jan (Ed.) et al.: ED-Media 2010 : World Conference on Educational Multimedia, Hypermedia & Telecommunications [online]. Chesapeake: AACE, 2010, pp. 860-869

Ontologies are used to represent knowledge and their semantic information from different topics, to allow users a better way to explore knowledge and find information faster, because of the data-structuring. To achieve a well filled knowledgebase, editors have to be used, to enter new and to edit existing information. But most of the existing ontology-editors are designed for experienced ontology-experts. Experts from other topic fields e.g. physicians are often novices in the area of ontology-creating, they need adequate tools, which hide the complexity of ontology-structures. In the area of e-learning experts are also teachers as well. In this paper we will present a method, how the needs of domain-experts can be regarded and so an editor can designed, which allows an editing and adding of information by users without having experiences of creating ontologies. With such an editor domain-experts are able to commit their expert-knowledge into the ontology.

Gómez Chova, Luis (Ed.) et al.: International Conference on Education and New Learning Technologies. Proceedings [CD-ROM] : EDULEARN10. Valencia: IATED, 2010, pp. 006427-006437

Graphical knowledge representations open promising perspectives to support the explorative learning on web. 2D-visualization are recently evaluated as gainful knowledge exploration systems, whereas 3D-visualization systems did not find their way into web-based explorative learning. 3D-visualizations and "3D Knowledge Worlds", as virtual environment in context of e-learning, comprise a high degree of authenticity, because the used metaphors are known by the users from the real world. But different challenges like the usage of 3D-Knowledge World without losing the learning context and the focused learning goals are rarely investigated and considered. New technologies provide the opportunity to introduce 3D-visualizations and environments on web to support a web-based explorative learning. Therefore it is necessary to investigate the prospects of 3D-visualization for transferring and adopting knowledge on web. The following paper describes different approaches to use 3D-visualization and Knowledge Worlds for conveying knowledge on web-based systems using web-based contents. The approaches for 3D visualizations are classified into different layout algorithm and the knowledge worlds are classified interaction character.

Signal Processing (IIH-MSP-2010), it is our pleasure to present to you the conference proceedings. Multimedia technologies with an increasing level of intelligence are emerging to enable the process of creating a global information infrastructure that will interconnect heterogeneous computer networks and various forms of information technologies around the world. IIHMSP-2010, which is the sixth edition of the IIHMSP series of conferences, is intended as an international forum for researchers and professionals in all area of information hiding and multimedia signal processing. The major areas covered at the conference and presented in the proceedings include: · Information Hiding and Security · Multimedia Signal Processing and Networking · Bio-Inspired Multimedia Technologies and Systems

The Fraunhofer Institute for Computer Graphics Research IGD with offices in Darmstadt as well as in Rostock, Singapore, and Graz, the partner institutes at the respective universities, the Interactive Graphics Systems Group of Technische Universität Darmstadt, the Computergraphics and Communication Group of the Institute of Computer Science at Rostock University, Nanyang Technological University (NTU), Singapore, and the Visual Computing Cluster of Excellence of Graz University of Technology, cooperate closely within projects and research and development in the field of Computer Graphics. The "Selected Readings in Computer Graphics 2009" consist of 38 articles selected from a total of 183 scientific publications contributed by all these institutions. All articles previously appeared in various scientific books, journals, conferences and workshops, and are reprinted with permission of the respective copyright holders. The publications had to undergo a thorough review process by internationally leading experts and established technical societies. Therefore, the Selected Readings should give a fairly good and detailed overview of the scientific developments in Computer Graphics in the year 2009. They are published by Professor Dieter W. Fellner, the director of Fraunhofer Institute for Computer Graphics Research IGD in Darmstadt, at the same time professor at the Department of Computer Science at Technische Universität Darmstadt, and professor at the Faculty of Computer Science at Graz University of Technology.

The Fraunhofer Institute for Computer Graphics Research IGD with offices in Darmstadt as well as in Rostock, Singapore, and Graz, the partner institutes at the respective universities, the Interactive Graphics Systems Group of Technische Universität Darmstadt, the Computergraphics and Communication Group of the Institute of Computer Science at Rostock University, Nanyang Technological University (NTU), Singapore, and the Visual Computing Cluster of Excellence of Graz University of Technology, cooperate closely within projects and research and development in the field of Computer Graphics. The "Selected Readings in Computer Graphics 2009" consist of 38 articles selected from a total of 183 scientific publications contributed by all these institutions. All articles previously appeared in various scientific books, journals, conferences and workshops, and are reprinted with permission of the respective copyright holders. The publications had to undergo a thorough review process by internationally leading experts and established technical societies. Therefore, the Selected Readings should give a fairly good and detailed overview of the scientific developments in Computer Graphics in the year 2009. They are published by Professor Dieter W. Fellner, the director of Fraunhofer Institute for Computer Graphics Research IGD in Darmstadt, at the same time professor at the Department of Computer Science at Technische Universität Darmstadt, and professor at the Faculty of Computer Science at Graz University of Technology.

Lewkowicz, Myriam (Ed.) et al.: Proceedings of COOP 2010 : Proceedings of the 9th International Conference on the Design of Cooperative Systems. Berlin, Heidelberg, New York: Springer, 2010, pp. 101-117

Collaborative Video Annotation is a broad field of research and is widely used in productive environments. While it is easy to follow changes in small systems with few users, keeping in touch with all changes in large environments can easily get overwhelming. The easiest way and a first approach to prevent the users from getting lost are to show them all changes in an appropriate way. This list of changes can also become very large when many contributors add new information to shared data resources. To prevent users from getting lost while having a list of changes, this paper introduces a way to subscribe to parts of the system and only to have the relevant changes shown. To achieve this goal, the framework provides an approach to check the relevance of changes, which is not trivial in three dimensional spaces, and to be accumulated for later reference by the subscribing user. The benefit for users is to need fewer times to be up-to-date and to have more time for applying own changes.

Herrington, Jan (Ed.) et al.: ED-Media 2010 : World Conference on Educational Multimedia, Hypermedia & Telecommunications [online]. Chesapeake: AACE, 2010, pp. 1224-1233

Annotation techniques for multimedia contents have found their way into multiple areas of daily use as well as professional fields. A large number of research projects can be assigned to different specific subareas of digital annotation. Nevertheless, the annotation process, bringing out multiple workflows depending on different application scenarios, has not sufficiently been taken into consideration. A consideration of respective processes and workflows requires detailed knowledge about practices of digital multimedia annotation. In order to establish fundamental groundwork towards workflow-related research, this paper presents a comprehensive process model of multimedia annotation which results from a conducted empirical study. Furthermore, we provide a survey of the tasks that have to be accomplished by users and computing devices, tools and algorithms that are used to handle specific tasks, and types of data that are transferred between workflow steps. These aspects are assigned to the identified sub-processes of the model.

Lewkowicz, Myriam (Ed.) et al.: Proceedings of COOP 2010 : Proceedings of the 9th International Conference on the Design of Cooperative Systems. Berlin, Heidelberg, New York: Springer, 2010, pp. 79-99

Collaborative annotation techniques for digital multimedia contents have found their way into a vast amount of areas of daily use as well as professional fields. Attendant research has issued a large number of research projects that can be assigned to different specific subareas of annotation. These projects focus on one or only few aspects of digital annotation. However, the whole annotation process as a operative unit has not sufficiently been taken into consideration, especially for the case of collaborative settings. In order to attend to that lack of research, we present a framework that supports multiple collaborative workflows related to digital multimedia annotation. In that context, we introduce a process-based architecture model, a formalized specification of collaborative annotation processes, and a concept for personalized workflow visualization and user assistance.

Annotation of digital multimedia comprises a range of different application scenarios, supported media and annotation formats, and involved techniques. Accordingly, recent annotation environments provide numerous functions and editing options. This results in complexly designed user interfaces, so that human operators are disoriented with respect to task procedures and the selection of accurate tools. In this thesis we contribute to the operability of multimedia annotation systems in several novel ways. We introduce concepts to support annotation processes, at which principles of Workflow Management are transferred. Particularly focusing on the behavior of graphical user interface components, we achieve a significant decrease of user disorientation and processing times. - In three initial studies, we investigate multimedia annotation from two different perspectives. A Feature-oriented Analysis of Annotation Systems describes applied techniques and forms of processed data. Moreover, a conducted Empirical Study and Literature Survey elucidate different practices of annotation, considering case examples and proposed workflow models. - Based on the results of the preliminary studies, we establish a Generic Process Model of Multimedia Annotation, summarizing identified sub-processes and tasks, their sequential procedures, applied services, as well as involved data formats. - By a transfer into a Formal Process Specification we define information entities and their interrelations, constituting a basis for workflow modeling, and declaring types of data which need to be managed and processed by the technical system. - We propose a Reference Architecture Model, which elucidates the structure and behavior of a process-based annotation system, also specifying interactions and interfaces between different integrated components. - As central contribution of this thesis, we introduce a concept for Process-driven User Assistance. This implies visual and interactive access to a given workflow, representation of the workflow progress, and status-dependent invocation of tools. We present results from a User Study conducted by means of the so-called SemAnnot framework. We implemented this novel framework based on our considerations mentioned above. In this study we show that the application of our proposed concept for process-driven user assistance leads to strongly significant improvements of the operability of multimedia annotation systems. These improvements are associated with the partial aspects efficiency, learnability, usability, process overview, and user satisfaction.

Computers & Graphics, Vol.34 (2010), 4, pp. 322-334; First published as article in Press 16 June 2010, DOI: 10.1016/j.cag.2010.05.007

The creation of building and facility models is a tedious and complicated task. Existing CAD models are typically not well suited since they contain too much or not enough detail; the manual modeling approach does not scale; different views on the same model are needed, and different levels of detail and abstraction; and finally, conventional modeling tools are inappropriate for models with many internal parameter dependencies. As a solution to this problem we propose a combination of a procedural approach with shape grammars. The model is created in a top-down manner; high-level changeability and re-usability are much less of a problem; and it can be interactively evaluated to provide different views at runtime. We present some insights on the relation between imperative and declarative grammar descriptions, and show a detailed case study with facility surveillance as a practical application.

Brazilian Computer Society (SBC): XII Symposium on Virtual and Augmented Reality : SVR 2010. Brazil: Everton Cavalcante, 2010, 4 p.

For many years the Graphics Processing Unit (GPU) of common desktops was just used to accelerate certain parts of the graphics pipeline. After developers had access to the native instruction set and memory of the massive parallel computational elements of GPUs a lot has changed. GPUs became powerful and programmable. Nowadays two SDKs are most used for GPU programming: CUDA and OpenCL. CUDA is the most adopted general purpose parallel computing architecture for GPUs but is restricted to Nvidia graphic cards only. In contrast, OpenCL is a new royalityfree framework for parallel programming intended to be portable across different hardware manufacturers or even different platforms. In this paper, we evaluate both solutions considering a typical parallel algorithm: Ray Tracing. We show our performance results and experiences on developing both implementations that could be easily adapted to solve other problems.

Computer Graphics Society (CGS): Computer Graphics International 2010. Short Papers : CGI [online]. [cited 01 February 2011] Available from: http://cgi2010.miralab.unige.ch/CGI_ShortPapersD4.html 2010, 4 p.

Despite the superior image quality generated by ray tracing, programmers of time-critical applications have historically avoided it because of its computational costs. Nowadays, the hardware of modern desktops allows the execution of realtime ray tracers but requires a specialized implementation based on specific characteristics of each application, such as scene complexity, kinds of motion, ray distribution, model structure and hardware. The evaluation and development of these requirements are complex and time-consuming, especially for developers with no familiarity in rendering algorithms and graphics hardware programming. The aim of our work is to provide a general and practical method to efficiently execute interactive ray tracing in most systems. We considered the most common aspects of current computer graphics applications, like the use of a scene graph and support to static and dynamic objects. In addition, we also took into account the common desktop hardware. This led us to the development of a special acceleration structure and its implementation on the GPU. In this paper, we present the development of our work showing the combination of different techniques and our results.

The focal point of this conference was digital heritage, which all of us involved in the documentation of cultural heritage continually strive to implement. The excellent selection of papers published in the proceedings reflects in the best possible way the benefits of exploiting modern technological advances for the restoration, preservation and e-documentation of any kind of cultural heritage. The topics covered included experiences in the use of innovative recording technologies and methods, and how to take best advantage of the results obtained to build up new instruments and improved methodologies for documenting in multimedia formats, archiving in digital libraries and managing a cultural heritage.

ACM SIGGRAPH: Proceedings Web3D 2010 : 15th International Conference on 3D Web Technology. New York: ACM Press, 2010, pp. 73-81

This paper presents methods based on the open standard X3D to rapidly describe life-like characters and other scene elements in the context of storyboarding and pre-visualization. Current frameworks that employ virtual agents often rely on non-standardized pipelines and lack functionality to describe lighting, camera staging or character behavior in a descriptive and simple manner. Even though demand for such a system is high, ranging from edutainment to pre-visualization in the movie industry, few such systems exist. Thereto, we present the ANSWER framework, which provides a set of interconnected components that aid a film director in the process of film production from the planning stage to post-production. Rich and intuitive user interfaces are used for scene authoring and the underlying knowledge model is populated using semantic web technologies over which reasoning is applied. This transforms the user input into animated pre-visualizations that enable a director to experience and understand certain film making decisions before production begins. In this context we also propose some extensions to the current X3D standard for describing cinematic contents.

ACM SIGGRAPH: Proceedings Web3D 2010 : 15th International Conference on 3D Web Technology. New York: ACM Press, 2010, pp. 147-150

3D applications, e.g. in the context of visualization or interactive design review, can require complex user interaction to manipulate certain elements, a typical task which requires standard user interface elements. However, there are still no generalized methods for selecting and manipulating objects in 3D scenes and 3D GUI elements often fail to gather support for reasons of simplicity, leaving developers encumbered to replicate interactive elements themselves. Therefore, we present a set of nodes that introduce different kinds of 2D user interfaces to X3D. We define a base type for these user interfaces called "InteractiveTexture", which is a 2D texture node implementing slots for input forwarding. From this node we derive several user interface representations to enable complex user interaction suitable for both, desktop and immersive interaction.

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. 302-309

The most challenging algorithmical task for markerless Augmented Reality applications is the robust estimation of the camera pose. With a given 3D model of a scene the camera pose can be estimated via model-based camera tracking without the need to manipulate the scene with fiducial markers. Up to now, the bottleneck of model-based camera tracking is the availability of such a 3D model. Recently time-of-flight cameras were developed which acquire depth images in real time. With a sensor fusion approach combining the color data of a 2D color camera and the 3D measurements of a time-of-flight camera we acquire a textured 3D model of a scene. We propose a semi-manual reconstruction step in which the alignment of several submeshes with a mesh processing tool is supervised by the user to ensure a correct alignment. The evaluation of our approach shows its applicability for reconstructing a 3D model which is suitable for model-based camera tracking even for objects which are difficult to measure reliably with a time-of-flight camera due to their demanding surface characteristics.

Höllerer, Tobias (Ed.) et al.: 9th IEEE International Symposium on Mixed and Augmented Reality 2010 : ISMAR. Science & Technology Proceedings. Los Alamitos, Calif.: IEEE Computer Society, 2010, pp. 241-242

For many tasks like markerless model-based camera tracking it is essential that the 3D model of a scene accurately represents the real geometry of the scene. It is therefore very important to detect deviations between a 3D model and a scene. We present an innovative approach which is based on the insight that camera tracking can not only be used for Augmented Reality visualization but also to solve the correspondence problem between 3D measurements of a real scene and their corresponding positions in the 3D model. We combine a time-of-flight camera (which acquires depth images in real time) with a custom 2D camera (used for the camera tracking) and developed an analysis-by-synthesis approach to detect deviations between a scene and a 3D model of the scene.

Kalkbrenner, Stefan (Ed.): 5. Multimediakongress Wismar 2010 : Netzwerk - Forschung - Innovation [CD-ROM], 6 p.

Shape grammar systems are the suitable method for modeling hierarchically structured 3D objects. A great variety of similar objects can be modeled using only a small set of rules. We present a prototypical graphical user interface for hierarchical volumetric modeling using the split grammar approach. Our focus is on creating split rules interactively rather than through scripting. Furthermore, we extend the concept of subdividing boxes to a more general representation and evaluate it in the context of generating 3D-facades of complex buildings.

Analysts need to effectively assess large amounts of data. Often, their focus is on two types of data: weighted directed graphs and two-dimensional time dependent data. These types of data are commonly examined in various application areas such as transportation, finance, or biology. The key elements in supporting the analysis are systems that seamlessly integrate interactive visualization techniques and data processing. The systems also need to offer the analyst the possibility to flexibly steer the analytical process. In this thesis, we present new techniques providing such flexible integrated combinations with tight user involvement in the analytical process for the two selected data types. We first develop new techniques for visual analysis of weighted directed graphs. - We enhance the analysis of entity relationships by integration of algorithmic analysis of connections in interactive visualization. - We improve the analysis of graph structure by several ways of motif-based analysis. - We introduce interactive visual clustering of graph connected components for gaining overview of the dataspace. Second, we develop new methods for visual analysis of two-dimensional time dependent data. We thereby combine animation and trajectory-based interactive visualizations with user-driven feature-based data analysis. - We extend guidelines for the use of animation by conducting a perception study of motion direction change. - We introduce interactive monitoring of a new set of data features in order to analyze the data dynamics. - We present visual clustering of trajectories of individual entities using self-organizing maps (SOM) with user control of the clustering process. As a basis for the development of the new approaches, we discuss the methodology of Visual Analytics and its related fields. We thereby extend classification of Information Visualization and Interaction techniques used in Visual Analytics systems. The developed techniques can be used in various application domains such as finance and economics, geography, social science, biology, transportation, or meteorology. In the financial domain, the techniques support analysts in making investment decisions, in assessment of company value, or in analysis of economy structure. We demonstrate our new methods on two real world data sets: shareholder networks and time-varying risk-return data.

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

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.

International Journal of Advanced Corporate Learning [online], Vol.3 (2010), 4, pp. 26-34

Semantic-Web technologies and ontology-based information processing systems are established techniques, in more than only research areas and institutions. Different worldwide projects and enterprise companies identified already the added value of semantic technologies, so they work on different sub-topics for gathering and conveying knowledge. As the process of gathering and structuring semantic information plays a key role in the most developed applications, the process of transferring and adopting knowledge to and by humans is neglected, although the complex structure of knowledge-design opens many research-questions. The customization of the presentation itself and the interaction techniques with these presentation artifacts is a key question for gainful and effective work with semantic information. The following paper describes a new approach for visualizing semantic information as a composition of different adaptable ontology-visualization techniques. We start with a categorized description of existing ontology visualization techniques and show potential gaps.

Gómez Chova, Luis (Ed.) et al.: International Conference on Education and New Learning Technologies. Proceedings [CD-ROM] : EDULEARN10. Valencia: IATED, 2010, pp. 006476-006484

The following paper describes the conceptual design of an Intelligent Exploration System (IES) that offers a user-adapted graphical environment of web-based knowledge repositories, to support and optimize the explorative learning. The paper starts with a short definition of learning by exploring and introduces the Intelligent Tutoring System and Semantic Technologies for developing such an Intelligent Exploration System. The IES itself will be described with a short overview of existing learner or user analysis methods, visualization techniques for exploring knowledge with semantics technology and the explanation of the characteristics of adaptation to offer a more efficient learning environment.

Auer, Michael (Ed.): ICL 2010 Proceedings [CD-ROM] : International Conference Interactive Computer Aided Learning. Kassel: University Press, 2010, pp. 163-173

Semantic-Web and ontology-based information processing systems are established technologies and techniques, in more than only research areas and institutions. Different worldwide projects and enterprise companies identified already the added value of semantic technologies and work on different sub-topics for gathering and conveying knowledge. As the process of gathering and structuring semantic information plays a key role in the most developed applications, the process of transferring and adopting knowledge to and by humans is neglected, although the complex structure of knowledge-design opens many research-questions. The following paper describes a new approach for visualizing semantic information as a composition of different adaptable ontology-visualization techniques. We start with a categorized description of existing ontology visualization techniques and show potential gaps. After that the new approach will be described and its added value to existing systems. A case study within the greatest German program for semantic information processing will show the usage of the system in real scenarios.

Huang, De-Shuang (Ed.) et al.: Advanced Intelligent Computing Theories and Applications : 6th International Conference on Intelligent Computing. Berlin, Heidelberg, New York: Springer, 2010. (Lecture Notes in Computer Science (LNCS) 6215), pp. 362-371

Adaptive User Interfaces are able to facilitate the handling of computer systems through the automatic adaptation to users' needs and preferences. For the realization of these systems, information about the individual user is needed. This user information can be extracted from user events by applying analytical methods without the active information input by the user. In this paper we introduce a reusable interaction analysis system based on probabilistic methods that predicts user interactions, recognizes user activities and detects user preferences on different levels of abstraction. The evaluation reveals that the prediction quality of the developed algorithm outperforms the quality of other established prediction methods.

Chen, Wen (Ed.) et al.: IEEE International Conference on Intelligent Computing and Intelligent Systems. Proceedings : ICIS 2010. New York: IEEE Press, 2010, pp. 607-612

Predictive statistical models are used in the area of adaptive user interfaces to model user behavior and to infer user information from interaction events in an implicit and non-intrusive way. This information constitutes the basis for tailoring the user interface to the needs of the individual user. Consequently, the user analysis process should model the user with information, which can be used in various systems to recognize user activities, intentions and roles to accomplish an adequate adaptation to the given user and his current task. In this paper we present the improved prediction algorithm KO*/19, which is able to recognize, beside interaction predictions, behavioral patterns for recognizing user activities. By means of this extension, the evaluation shows that the KO*/19-Algorithm improves the Mean Prediction Rank more than 19% compared to other well-established prediction algorithms.

Artusi, Alessandro (Ed.) et al.: VAST 2010. : Eurographics Symposium Proceedings. Goslar: Eurographics Association, 2010, pp. 105-114; 182 (Color plate)

This paper describes the design and the implementation of a distributed object repository that offers cultural heritage experts and practitioners a working platform to access, use, share and modify digital content. The principle of collecting paradata to document each step in a potentially long sequence of processing steps implies a number of design decisions for the data repository, which are described and explained. Furthermore, we provide a description of the concise API our implementation. Our intention is to provide an easy-to-understand recipe that may be valuable also for other data repository implementations that incorporate and operationalize the more theoretical concepts of intellectual transparency, collecting paradata, and compatibility to semantic networks.

The American Society of Mechanical Engineers (ASME): ASME International Design Engineering Technical Conferences & Computers and Information in Engineering Conference : DETC 2010. New York: The American Society of Mechanical Engineers, 2010, 10 p.

The engineering design is a systematic approach implemented in the product development process, which is composed of several phases and supported by different tools. Computer-Aided Design (CAD) and Computer-Aided Engineering (CAE) tools are particularly dedicated to the embodiment phase and these enable engineers to design and analyze a potential solution. Nonetheless, the lack of integration between CAD and CAE restricts the exploration of design variations. Hence, we aim at incorporating functionalities of a CAD system within a CAE environment, by means of building a high level representation of the mesh and allowing the engineer to handle and manipulate semantic features, avoiding the direct manipulation of single elements. Thus, the engineer will be able to perform extruding, rounding or dragging operations regardless of geometrical and topological limitations. We present in this paper, the intelligence that a simulating mesh needs to support, in order to enable such operations.

Fischer, Xavier (Ed.) et al.: Research in Interactive Design. Volume 3 : Virtual, Interactive and Integrated Product Design and Manufacturing for Industrial Innovation. Paris, Berlin, Heidelberg: Springer, 2010, 6 p.

During the last two decades, several approaches have been proposed, in order to deal with the integration in the embodiment phase of the engineering design. This phase deals with the virtual product development and it is supported by Computer-Aided Design (CAD) and Computer-Aided Engineering (CAE). Nonetheless, this integration has not really been achieved. There is a well established communication from design to analysis, but there is a lack of design operations and functionalities within an analysis environment. This lack of integration will always be presented as long as there are used different representation schemes for design and analysis. Hence, Embodiment Mesh Processing (EMP) is based on a common mesh representation and it aims to provide mesh-based modeling functionalities within an analysis environment. We present our reasoning behind EMP and the needed building blocks for enabling a fully integrated design-analysis interaction loop and the exploration of design variations.

ACM SIGGRAPH: Proceedings Web3D 2010 : 15th International Conference on 3D Web Technology. New York: ACM Press, 2010, pp. 55-61

In this paper we present a software architecture for the integration of a RESTful web service interface in OpenSG applications. The proposed architecture can be integrated into any OpenSG application with minimal changes to the sources. Extending a scene graph application with a web service interface offers many new possibilities. Without much effort it is possible to review and control the scene and its components using a web browser. New ways of (browser based) user interactions can be added on all kinds of web enabled devices. As an example we present the integration of "SweetHome3D" into an existing virtual reality setup.

Kalkbrenner, Stefan (Ed.): 5. Multimediakongress Wismar 2010 : Netzwerk - Forschung - Innovation [CD-ROM], 8 p.

Integrating a web service into an application based on the OpenSG scene graph system makes it possible to access and modify the contents of the scene graph during runtime without recompilation of the application. These features offer many new possibilities in interacting with the OpenSG application and the scene graph. The main features of our web service are querying the contents of the scene graph, adding and deleting of nodes and changing properties of nodes.

Ioannides, Marinos (Ed.) et al.: Digital Heritage. Third International Conference, EuroMed 2010. Berlin, Heidelberg, New York: Springer, 2010. (Lecture Notes in Computer Science (LNCS) 6436), pp. 153-165

Within the last few years generative modeling techniques have gained attention especially in the context of cultural heritage. As a generative model describes a rather ideal object than a real one, generative techniques are a basis for object description and classification. This procedural knowledge differs from other kinds of knowledge, such as declarative knowledge, in a significant way. It can be applied to a task. This similarity to algorithms is reflected in the way generative models are designed: they are programmed. In order to make generative modeling accessible to cultural heritage experts, we created a generative modeling framework which accounts for their special needs. The result is a generative modeler (http://www.cgv.tugraz.at/euclides) based on an easy-to-use scripting language (JavaScript). The generative model meets the demands on documentation standards and fulfils sustainability conditions. Its integrated meta-modeler approach makes it independent from hardware, software and platforms

Lensch, Hendrik P. A. (Ed.) et al.: Eurographics 2010. Short Papers, pp. 49-52

Spectral rendering takes the full visible spectrum into account when calculating light-surface interaction and can overcome the well-known deficiencies of rendering with tristimulus color models. We present a variant of the precomputed radiance transfer algorithm that is tailored towards real-time spectral rendering on modern graphics hardware. Our method renders diffuse, self-shadowing objects with spatially varying spectral reflectance properties under distant, dynamic, full-spectral illumination. To achieve real-time frame rates and practical memory requirements we split the light transfer function into an achromatic part that varies per vertex and a wavelength-dependent part that represents a spectral albedo texture map. As an additional optimization, we project reflectance and illuminant spectra into an orthonormal basis. One area of application for our research is virtual design applications that require relighting objects with high color fidelity at interactive frame rates.

ACM SIGGRAPH: Proceedings Web3D 2010 : 15th International Conference on 3D Web Technology. New York: ACM Press, 2010, pp. 7-15

This paper introduces a modern, declarative surface shader for the X3D standard that allows for a compact, expressive, and implementation-independent specification of surface appearance. X3D's Material node is portable, but its feature set has become inadequate over the last years. Explicit shader programs, on the other hand, offer the expressive power to specify advanced shading techniques, but are highly implementation-dependent. The motivation for our proposal is to bridge the gap between these two worlds - to provide X3D with renderer-independent support for modern materials and to increase interoperability with DCC tools. At the core of our proposal is the CommonSurfaceShader node. This node provides no explicit shader code, only a slim declarative interface consisting of a set of parameters with clearly defined semantics. Implementation details are completely hidden and portability is maximized. It supports diffuse and glossy surface reflection, bump mapping, and perfect specular reflection and refraction. This feature set can capture the appearance of many common materials accurately and is easily mappable to the material descriptions of other software packages and file formats. To verify our claims, we have implemented and analyzed the proposed node in three different rendering pipelines: a renderer based on hardware accelerated rasterization, an interactive ray tracer, and a path tracer.

Herrington, Jan (Ed.) et al.: ED-Media 2010 : World Conference on Educational Multimedia, Hypermedia & Telecommunications [online]. Chesapeake: AACE, 2010, pp. 911-919

Ontologies have become an established data model for conceptualizing knowledge entities and describing semantic relationships between them. They are used to model the concepts of specific domains and are widespread in the areas of the semantic web, digital libraries and multimedia database management. To gain the most possible benefit from this data model, it is important to offer adequate visualizations, so that users can easily acquire the knowledge. Most ontology visualization techniques are based on hierarchical or graph-based visualization metaphors. This may result in information-loss, visual clutter, cognitive overload or context-loss. In this paper we describe a new approach of ontology visualization technique called SemaSun that is based on the sunburst visualization metaphor. We improved this metaphor, which is naturally designed for displaying hierarchical data, to the tasks of displaying multiple inheritance and semantic relations. This approach also offers incremental ontology exploring to reduce the cognitive load without losing the informational context.

Bebis, George (Ed.) et al.: Advances in Visual Computing. 6th International Symposium, ISVC 2010 : Proceedings, Part III. Berlin, Heidelberg, New York: Springer, 2010. (Lecture Notes in Computer Science (LNCS) 6455), pp. 514-523

Timeline based visualizations arrange time-dependent entities along a time-axis and are used in many different domains like digital libraries, criminal investigation and medical information systems to support users in understanding chronological structures. By the use of semantic technologies, the information is categorized in a domain-specific, hierarchical schema and specified by semantic relations. Commonly semantic relations in timeline visualizations are depicted by interconnecting entities with a directed edge. However it is possible that semantic relations change in the course of time. In this paper we introduce a new timeline visualization for time-dependent semantics called SemaTime that offers a hierarchical categorization of time-dependent entities including navigation and filtering features. We also present a novel concept for visualizing time-dependent relations that allows the illustration of time-varying semantic relations and affords an easy understandable visualization of complex, time-dependent interrelations.

Bebis, George (Ed.) et al.: Advances in Visual Computing. 6th International Symposium, ISVC 2010 : Proceedings, Part III. Berlin, Heidelberg, New York: Springer, 2010. (Lecture Notes in Computer Science (LNCS) 6455), pp. 514-523

Timeline based visualizations arrange time-dependent entities along a time-axis and are used in many different domains like digital libraries, criminal investigation and medical information systems to support users in understanding chronological structures. By the use of semantic technologies, the information is categorized in a domain-specific, hierarchical schema and specified by semantic relations. Commonly semantic relations in timeline visualizations are depicted by interconnecting entities with a directed edge. However it is possible that semantic relations change in the course of time. In this paper we introduce a new timeline visualization for time-dependent semantics called SemaTime that offers a hierarchical categorization of time-dependent entities including navigation and filtering features. We also present a novel concept for visualizing time-dependent relations that allows the illustration of time-varying semantic relations and affords an easy understandable visualization of complex, time-dependent interrelations.

International Academy, Research, and Industry Association (IARIA): Computation Tools 2010 : The First International Conference on Computational Logics, Algebras, Programming, Tools, and Benchmarking, pp. 14-21

Offering an easy access to programming languages that are difficult to approach directly dramatically reduces the inhibition threshold. The Generative Modeling Language is such a language and can be described as being similar to Adobe's PostScript. A major drawback of all PostScript dialects is their unintuitive reverse Polish notation, which makes both - reading and writing - a cumbersome task. A language should offer a structured and intuitive syntax in order to increase efficiency and avoid frustration during the creation of code. To overcome this issue, we present a new approach to translate JavaScript code to GML automatically. While this translation is basically a simple infix-to-postfix notation rewrite for mathematical expressions, the correct translation of control flow structures is a non-trivial task, due to the fact that there is no concept of "goto" in the PostScript language and its dialects. The main contribution of this work is the complete translation of JavaScript into a PostScript dialect including all control flow statements. To the best of our knowledge, this is the first complete translator.

Skala, Vaclav (Ed.): WSCG 2010. Full Papers Proceedings. Plzen: University of West Bohemia, 2010, pp. 1-8

Subdivision surfaces are an established modeling tool in computer graphics and computer-aided design. While the theoretical foundations of subdivision surfaces are well studied, the correlation between a control mesh and its subdivided limit surface still has some open-ended questions: Which topology should a control mesh have? Where should control vertices be placed? A modeler - human or software - is confronted with these questions and has to answer them. In this paper we analyze four characteristic situations. Each one consists of an analytical reference surface S and several variants of control meshes Ci. In order to concentrate on the topology of the control meshes, the geometrical positions of their control vertices have been determined and optimized automatically. As a result we identified the best topology of all Ci to represent the given surface S. Based on these results we derived heuristics to model with subdivision surfaces. These heuristics are beneficial for all modelers.

Skala, Vaclav (Ed.): WSCG 2010. Poster Proceedings. Plzen: University of West Bohemia, 2010, pp. 5-8

Procedural modeling is a technique to describe 3D objects by a constructive, generative description. In order to tap the full potential of this technique the content creator needs to be familiar with two worlds - procedural modeling techniques and computer graphics on the one hand as well as domain-specific expertise and specialized knowledge on the other hand. This article presents a JavaScript-based approach to combine both worlds. It describes a modeling tool for generative modeling whose target audience consists of beginners and intermediate learners of procedural modeling techniques. Our approach will be beneficial in various contexts. JavaScript is a wide-spread, easy-to-use language. With our tool procedural models can be translated from JavaScript to various generative modeling and rendering systems.

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. 65-71

In this work we introduce an approach for reconstructing digital 3D models from multiple perspective line drawings. One major goal is to keep the required user interaction simple and at a minimum, while making no constraints to the objects shape. Such a system provides a useful extension for digitalization of paper-based styling concepts, which today is still a time consuming process. In the presented method the line drawings are first decomposed in curves assembling a network of curves. In a second step, the positions for the endpoints of the curves are determined in 3D, using multiple sketches and a virtual camera model given by the user. Then the shapes of the 3D curves between the reconstructed 3D endpoints are inferred. This leads to a network of 3D curves, which can be used for first visual evaluations in 3D. During the whole process only little user interaction is needed, which only takes place in the pre- and post-processing phases. The approach has been applied on multiple sketches and it is shown that the approach creates plausible results within reasonable timing.

The analysis of deformable objects which have a high-degree of freedom has long been encouraged by numerous researchers because it can be applied to such diverse areas as medical engineering, video surveillance and monitoring, Human Computer Interaction, browsing of video databases, interactive gaming and other growing applications. Within the computerized environments, the systems are largely separated into marker based motion capture and markerless motion capture. In particular, markerless motion capture and analysis have also been heavily studied by numerous researchers using local features, color, shape, texture, and depth map from stereo vision, but it is still a challenging issue in the area of computer vision and computer graphics due to partial occlusion, clutter, dependency of camera viewpoints, high-dimensional state space and pose ambiguity within the target object. In this thesis, we address the issue of the efficient markerless motion capture and representation methodology using skeletal features for the purpose of analysis and recognition of their motion patterns in video sequences. To localize the motion of the target object in a 2D image and 3D volume, we extract the skeletal features by analyzing its Normalized Gradient Vector Flow in the space of diffusion tensor fields since skeletal features are more robust and efficient than other features in recognizing and analyzing the deformable object. The skeletal features within the target object are automatically merged and split by measuring the dissimilarity of tensorial characteristics between neighbor pixels and voxels. The split skeletal features are used as features in human action recognition to understand human motion and target object detection and retrieval for Content based Image Retrieval. This thesis provides the following contributions to the fields of computer vision and computer graphics: (i) it introduces the notion of the features in the space of diffusion tensor fields and evaluates the successful analysis method of such features for motion interpretation, (ii) it presents a theory and an evaluation of the methods for automatic skeleton splitting and merging with respect to similarity measure between neighbor pixels in two dimension or voxels in three dimension and, (iii) it presents and demonstrates our proposed principle methodologies for diverse applications such as human action recognition or sketch-based image retrieval. With our system we can robustly handle several computer vision tasks to recognize and understand the motion of the target object without any prior information. In particular, the human action recognition using 3D reconstruction from multiple images and the skeleton splitting procedure is firstly proposed in this thesis and shown to be a useful and stable methodology. Furthermore, users can easily express their intention by sketching the characteristics of a target object and derive available related objects from a data base by using our proposed method.

Puppo, Enrico (Ed.) et al.: Eigth Eurographics Italian Chapter Conference : Eurographics Italian Chapter Proceedings. Goslar: Eurographics Association, 2010, pp. 41-48

Lighting conditions can make the difference between success or failure of an architectural space. The vision of space-light co-design is that architects can control the impression of an illuminated space already at an early design stage, instead of first designing spaces and then searching for a good lighting setup. As a first step towards this vision we propose a novel method to calculate potential light source positions from a given user defined target illumination. The method is independent of the tessellation of the scene and assumes a homogeneous diffuse Lambertian material. This allows using a voting system that determines potential positions for standard light sources with chosen size and brightness. Votes are cast from an illuminated surface point to all potential positions of a light source that would yield this illumination. Vote clusters consequently indicate a more probable light source position. With a slight extension the method can also identify mid-air light source positions.

Grimm, Cindy (Ed.) et al.: ACM SIGGRAPH / Eurographics Symposium on Sketch-Based Interfaces and Modeling 2009. Proceedings. New York: ACM, 2009, pp. 61-68

We describe a 3D modeling system that combines subdivision surfaces with sketch-based modeling in order to meet two conflicting goals: ease of use and fine-grained shape control. For the excellent control, low-poly modeling is still the method of choice for creating high-quality 3D models, e.g., in the games industry. However, direct mesh editing can be very tedious and time consuming. Our idea is to include also stroke-based techniques for rapidly modeling regular surface parts. We propose a simple and efficient algorithm for converting a 2D stroke to a control polygon suitable for Catmull/Clark subdivision surfaces. We have realized a small but reasonably rich set of interactive modeling tools to assess the expressiveness of stroke-based mesh design with a number of examples.

Fellner, Dieter W. (General Co-Chair) et al.: Proceedings Web3D 2009 : 14th International Conference on 3D Web Technology. New York: ACM Press, 2009, pp. 111-118

We present a framework for formulating domain-dependent 3D search queries suitable for content-based 3D search over the web. Users are typically not willing to spend much time to create a 3D query object. They expect to quickly see a result set in which they can navigate by further differentiating the query object. Our system innovates by using a streamlined parametric 3D modeling engine on both client and server side. Parametric tools have greater expressiveness, they allow shape manipulation through a few highlevel parameters, as well as incremental assembly of query objects. Short command strings are sent from client to server to keep the query objects on both sides in sync. This reduces turnaround times and allows asynchronous updates of live result sets.

The Fraunhofer Institute for Computer Graphics Research IGD with offices in Darmstadt as well as in Rostock and Graz, the partner institutes at the respective universities, the Interactive Graphics System Group of Technische Universität Darmstadt, the Computergraphics and Communication Group of the Institute of Computer Science at Rostock University, and the Visual Computing Cluster of Excellence of Graz University of Technology, together with the Centre for Advances Media Technology CAMTech, a co-foundation of Fraunhofer IGD with Nanyang Technological University (NTU), Singapore, and the Spanish Visual Communication and Interaction Technologies Centre Vicomtech, cooperate closely within projects and research and development in the field of Computer Graphics. The "Selected Readings in Computer Graphics 2008" consists of 41 articles selected from a total of 190 scientific publications contributed by all these institutions. All articles previously appeared in various scientific books, journals, conferences and workshops, and are reprinted with permission of the respective copyright holders. The publications had to undergo a thorough review process by internationally leading experts and established technical societies. Therefore, the Selected Readings should give a fairly good and detailed overview of the scientific developments in Computer Graphics in the year 2008. They are published by Professor José Luís Encarnação, and Professor Dieter W. Fellner, the director of Fraunhofer Institute for Computer Graphics Research IGD in Darmstadt. Both are professors at the Department of Computer Science at Technische Universität Darmstadt.

The Fraunhofer Institute for Computer Graphics Research IGD with offices in Darmstadt as well as in Rostock and Graz, the partner institutes at the respective universities, the Interactive Graphics System Group of Technische Universität Darmstadt, the Computergraphics and Communication Group of the Institute of Computer Science at Rostock University, and the Visual Computing Cluster of Excellence of Graz University of Technology, together with the Centre for Advances Media Technology CAMTech, a co-foundation of Fraunhofer IGD with Nanyang Technological University (NTU), Singapore, and the Spanish Visual Communication and Interaction Technologies Centre Vicomtech, cooperate closely within projects and research and development in the field of Computer Graphics. The "Selected Readings in Computer Graphics 2008" consists of 41 articles selected from a total of 190 scientific publications contributed by all these institutions. All articles previously appeared in various scientific books, journals, conferences and workshops, and are reprinted with permission of the respective copyright holders. The publications had to undergo a thorough review process by internationally leading experts and established technical societies. Therefore, the Selected Readings should give a fairly good and detailed overview of the scientific developments in Computer Graphics in the year 2008. They are published by Professor José Luís Encarnação, and Professor Dieter W. Fellner, the director of Fraunhofer Institute for Computer Graphics Research IGD in Darmstadt. Both are professors at the Department of Computer Science at Technische Universität Darmstadt.

The 2nd Sino-German Workshop "Virtual Reality & Augmented Reality in Industry" : Invited Paper Proceedings. Participants Edition. Shanghai: Shanghai Jiao Tong University, 2009, pp. 78-83

Rapid development in processing power, graphic cards and mobile computers open up a wide domain for Mixed Reality applications. Thereby the Mixed Reality continuum covers the complete spectrum from Virtual Reality using immersive projection technology to Augmented Reality using mobile systems like Smartphones and UMPCs. At the Fraunhofer Institute for Computer Graphics (IGD) the Mixed Reality Framework instantreality (www.instantreality.org) has been developed as a single and consistent interface for AR/VR developers. This framework provides a comprehensive set of features to support classic Virtual Reality (VR) as well as mobile Augmented Reality (AR). The goal is to provide a very simple application interface which includes the latest research results in the fields of high-realistic rendering, 3D user interaction and total-immersive display technology. The system design is based on various industry standards to facilitate application development and deployment.

Bullinger, Hans-Jörg (Ed.): Technology Guide : Principles, Applications, Trends. Berlin, Heidelberg, New York: Springer, 2009, pp. 250-255

The rapid development of microprocessors and graphics processing units (GPUs) has had an impact on information and communication technologies (lCT) over recent years. "Shaders" offer real-time visualisation of complex, computer-generated 3D models with photorealistic quality. Shader technology includes hardware and software modules which colour virtual 3D objects and model reflective properties. These developments have laid the foundations for mixed reality systems which enable both immersion into and realtime interaction with the environment. These environments are based on Milgram's mixed reality continuum where reality is a gradated spectrum ranging from real to virtual spaces.

IEEE Transactions on Instrumentation and Measurement, Vol.58 (2009), 9, pp. 3086-3093

In this paper, we present efficient height/distance field data structures for line-of-sight (LOS) queries on terrains and collision queries on arbitrary 3-D models. The data structure uses a pyramid of quad-shaped regions with the original height/distance field at the highest level and an overall minimum/maximum value at the lower levels. The pyramid can compactly be stored in a wavelet-like decomposition but using max and plus operations. Additionally, we show how to get minimum/maximum values for regions in a wavelet decomposition using real algebra. For LOS calculations, we compare with a kd-tree representation containing the maximum height values. Furthermore, we show that the LOS calculation is a special case of a collision detection query. Using our wavelet-like approach, even general and arbitrary collision detection queries can efficiently be answered.

IEEE Transactions on Instrumentation and Measurement, Vol.58 (2009), 9, pp. 3086-3093

In this paper, we present efficient height/distance field data structures for line-of-sight (LOS) queries on terrains and collision queries on arbitrary 3-D models. The data structure uses a pyramid of quad-shaped regions with the original height/distance field at the highest level and an overall minimum/maximum value at the lower levels. The pyramid can compactly be stored in a wavelet-like decomposition but using max and plus operations. Additionally, we show how to get minimum/maximum values for regions in a wavelet decomposition using real algebra. For LOS calculations, we compare with a kd-tree representation containing the maximum height values. Furthermore, we show that the LOS calculation is a special case of a collision detection query. Using our wavelet-like approach, even general and arbitrary collision detection queries can efficiently be answered.

Wissensarbeiter sind heutzutage hohen Anforderungen ausgesetzt. Sie müssen ständig neue Arbeitsfelder erschließen und sich schnell auf neue Gegebenheiten einstellen. Die vorliegende Dissertationsschrift stellt einen neuen Ansatz vor, Arbeitende an wissensintensiven Arbeitsplätzen mit kontextualisierten Visualisierungen zu unterstützen. Diese visuelle Unterstützung richtet sich dabei an der aktuellen Arbeitssituation (dem Kontext) des Wissensarbeiters aus. Dadurch wird es möglich, den spezifischen Problemen und Herausforderungen direkt am Arbeitsplatz zu begegnen und automatisierte Hilfestellung während der Arbeit anzubieten. Geeignete angepasste Visualisierungen können die Daten am wissensintensiven Arbeitsplatz intuitiv darstellen. Dies gestattet zum Beispiel die einfachere Identifikation von wichtigen Informationen, Dokumenten und Personen. Kontextinformationen stellen dabei eine sehr gut geeignete Quelle für die Anpassung der Visualisierungen an die aktuelle Arbeitssituation (Kontextualisierung) dar. Um diesen Möglichkeiten zu begegnen wurde ein Rahmenwerk zur kontextualisierten Visualisierung entwickelt. Dieses Rahmenwerk wurde im Zuge der vorliegenden Arbeit in mehreren Szenarios eingesetzt, instantiiert und sowohl quantitativ als auch qualitativ evaluiert. Dabei zeigte die Evaluation mit realistischen Daten und repräsentativen Versuchspersonen eine signifikante Steigerung der Produktivität. Dies wird vor allem in der gemessenen Zeit und Arbeitsqualität reflektiert. Zudem erfolgte in der Evaluation eine positive Rückmeldung zur individuellen Wahrnehmung des Rahmenwerks. Als wissenschaftliches und technisches Ergebnis dieser Arbeit liegt das Rahmenwerk mit allen Schnittstellen, Definitionen und Instantiierungen vor. Dabei ermöglicht das Rahmenwerk insbesondere ein einfaches Einbringen verschiedener Visualisierungsformen, Daten- und Kontextquellen.

ACM Journal on Computing and Cultural Heritage, Vol.2 (2009), 1, pp. 4:1-4:13

It is still a big technical problem to establish a relation between a shape and its meaning in a sustainable way. We present a solution with a markup method that allows for labeling parts of a 3D object very much like labeling parts of a hypertext. A 3D markup can serve both as hyperlink and as link anchor, which is the key to bidirectional linking between 3D objects and Web documents. Our focus is on a sustainable 3D software infrastructure for application scenarios ranging from email and Internet over authoring and browsing semantic networks to interactive museum presentations. We demonstrate the workflow and the effectiveness of our tools by redoing the Arrigo 3D Showcase. We are working towards a best practice example for information modeling in cultural heritage.

Cordeiro, José (Ed.) et al.: CSEDU 2009 : Proceedings of the First International Conference on Computer Supported Education. Volume 2. Setúbal: INSTICC Press, 2009, pp. 199-204

There is a growing number of application scenarios for computer-supported video annotation and analysis in educational settings. In related research work, a large number of different research fields and approaches have been involved. Nevertheless, the support of the annotation workflow has been little taken into account. As a first step towards developing a framework that assist users during the annotation process, the single work steps, tasks and sequences of the workflow had to be identified. In this paper, a model of the underlying annotation workflow is illustrated considering its single phases, tasks, and iterative loops that can be especially associated with the collaborative processes taking place.

HCI International 2009. Proceedings and Posters [DVD-ROM] : With 10 further Associated Conferences. Berlin, Heidelberg, New York: Springer, 2009. (Lecture Notes in Computer Science (LNCS)), LNCS 5621, pp. 33-42

In video annotation research, the support of the video annotation workflow has been taken little into account, especially concerning collaborative use cases. Previous research projects focus each on a different essential part of the whole annotation process. We present a reference architecture model which is based on identified phases of the video annotation workflow. In a first step, the underlying annotation workflow is exemplified with respect to its single phases, tasks, and loops. Secondly, the system architecture is going to be exemplified with respect to its elements, their internal procedures, as well as the interaction between these elements. The goals of this paper are to provide the reader with a basic understanding of the specific characteristics and requirements of collaborative video annotation processes, and to define a reference framework for the design of video annotation systems that include a workflow management system.

Schwill, Andreas (Ed.) et al.: DeLFI 2009 : DeLFI 2009. Die 7. E-Learning Fachtagung Informatik der Gesellschaft für Informatik e.V.. Bonn: Köllen, 2009. (GI-Edition - Lecture Notes in Informatics (LNI) P-153), pp. 115-126

Computergestützte Annotation und Analyse von Videoinhalten finden zunehmend Anwendung in unterschiedlichen Lehr-Lernszenarien. Eine Reihe von Projekten hat sich mit dem Forschungsbereich Videoannotation mit unterschiedlichen Forschungsschwerpunkten beschäftigt, diese fokussierten jedoch stets einen oder nur wenige Bestandteile des gesamten Annotationsprozesses. Bisher wurde den einzelnen Aufgaben, Prozessen und Abläufen, die einer (kollaborativen) Annotation von Videos zugrunde liegen, keine ausreichende Beachtung geschenkt. In diesem Beitrag möchten wir unter besonderer Berücksichtigung von einer Applikation in kollaborativen Lehr-Lernsituationen ein Modell präsentieren, das die Phasen, die zu erledigenden Aufgaben sowie die konkreten Abläufe innerhalb von Videoannotationsprozessen beschreibt.

Wandke, Hartmut (Ed.) et al.: Mensch & Computer 2009 : 9. Fachübergreifende Konferenz für interaktive und kooperative Medien. München: Oldenbourg, 2009, pp. 173-182

Various research projects already followed up the design of video annotation applications. Nevertheless, collaborative application scenarios as well as the need of users regarding the annotation workflow have been taken little into account. This paper discusses requirements for the design of video annotation systems. As our main contribution, we consider aspects that can be associated with collaborative use scenarios as well as requirements respecting the support of the annotation workflow not only considering the tasks but also the processes and sequences within. Our goals are to provide the reader with an understanding of the specific characteristics and requirements of video annotation, to establish a framework for evaluation, and to guide the design of video annotation tools.

Debattista, Kurt (Ed.) et al.: VAST 2009. Proceedings. Aire-la-Ville: Eurographics Association, 2009, pp. 117-124

Sharing 3D models with embedded annotations and additional information in a general accessible way still is a major challange. Using 3D technologies must become much easier, in particular in areas such as Cultural Heritage, where archeologists, art historians, and museum curators rely on robust, easy to use solutions. Sustainable exchange standards are vital since unlike in industry, no sophisticated PLM or PDM solutions are common in CH. To solve this problem we have examined the PDF file format and developed concepts and software for the exchange of annotated 3D models in a way that is not just comfortable but also sustainable. We show typical use cases for authoring and using PDF documents containing annotated 3D geometry. The resulting workflow is eficient and suitable for experienced users as well as for users working only with standard word processing tools and e-mail clients (plus, currently, Acrobat Pro Extended).

Debattista, Kurt (Ed.) et al.: VAST 2009. Proceedings. Aire-la-Ville: Eurographics Association, 2009, pp. 117-124

Sharing 3D models with embedded annotations and additional information in a general accessible way still is a major challange. Using 3D technologies must become much easier, in particular in areas such as Cultural Heritage, where archeologists, art historians, and museum curators rely on robust, easy to use solutions. Sustainable exchange standards are vital since unlike in industry, no sophisticated PLM or PDM solutions are common in CH. To solve this problem we have examined the PDF file format and developed concepts and software for the exchange of annotated 3D models in a way that is not just comfortable but also sustainable. We show typical use cases for authoring and using PDF documents containing annotated 3D geometry. The resulting workflow is eficient and suitable for experienced users as well as for users working only with standard word processing tools and e-mail clients (plus, currently, Acrobat Pro Extended).

Hirose, Michitaka (Ed.) et al.: Virtual Environments 2009 : Joint Virtual Reality Conference of EGVE - ICAT - EuroVR. Aire-la-Ville: Eurographics Association, 2009, pp. 109-112

In this paper, we present the usage of the Remote Desktop Protocol to integrate arbitrary, legacy applications in various environments. This approach accesses a desktop on a real computer or within a virtual machine. The result is not one image of the whole desktop, but a sequence of images of all desktop components (windows, dialogs, etc.). These components are rendered into textures and fed into a rendering framework (OpenSG). There the functional hierarchy is represented by a scene graph. In this way the desktop components can be rearranged freely and painted according to circumstances of the graphical environment supporting a wide range of display settings - from immersive environments via high-resolution tiled displays to mobile devices.

Ioannides, Marinos (Ed.) et al.: Digital Heritage. Proceedings of the 14th International Conference on Virtual Systems and Multimedia. Full Papers : VSMM 2008, pp. 187-193

We propose a novel general method to enrich ordinary 3D models with semantic information. Based on the Collada format this approach fits perfectly into the XML world: It allows bi-directional linking, from a web resource to a (part of) a 3D model, and the reverse direction as well. We also describe our software framework prototype for 3D-annotation by non-3D-specialists, in our case cultural heritage professionals.

The compensation of motion artifacts during Magnetic Resonance Imaging (MRI) of the head is essential to get excellent images. The detection of motion is sometimes done by the MRI system itself to reduce the artifacts (so-called navigators or navigators echoes). This prolongs the scan time and needs additional radio frequency (RF) pulses, not utilizing the whole available magnetization for imaging and interrupting steady-state image readout. Moreover the motion information is delayed by at least one repetition time (TR) available, because of data processing. Further on, eddy currents are produced so that detection of motion is not entirely compatible with the imaging acquisition sequences. Also, the planning time for the image acquisition is longer, because the localization of the navigator differs among patients. Therefore these techniques are not settled and rarely used in the clinical routine. In this work a new method was developed, which is able to detect and compensate the head motion simultaneously to the image acquisition. To achieve this, the gradients and the RF are updated depending on motion data detected by an optical tracking system in order to compensate the motion. The compatibility of the stereoscopic tracking system and the MRI was analyzed first. Markers, developed to be visible in both modalities, are used in the calibration procedure for correlating the coordinate systems. In a first version a time synchronized acquisition scheme of both systems was used to compensate a translational motion retrospectively. In a second version the motion data is handled from the MRI system directly to compensate motion prospectively. For the prospective trials, two optical systems with an accuracy of 200µm RMS and 60µm RMS were evaluated. It has been shown that the accuracy of the motion detection is significant for the success of the correction. A "volume to volume -" followed by a "slice to slice-" and finally a "line to line-" correction was performed. For that the MR sequences for echo planar imaging (EPI), spin echo (SE), gradient echo (GRE) and turbo spin echo (TSE) were adapted to work with optical prospective motion correction (OPROMOC) on phantoms and humans. Several times the calibration phase and the construction were re-engineered in order to eventually get an isotropic accuracy of 60µm with a latency time of less than 32 ms. In addition the technique was compared to established motion compensation techniques. In spectroscopic MR data acquisition, which is used to display metabolic information, the OPROMOC technique was the first technique to correct motion artifacts. Initial applications of the optical tracking system in functional imaging (fMRI), high resolution imaging and spectroscopy have shown that the technique will be convenient for brain imaging, registration and acquisition of metabolic information.

The International Network of Institutions for advanced education, training and R&D in Computer Graphics technology, systems and applications (INI-GraphicsNet) is the largest research network worldwide entirely dedicated to the field of Computer Graphics. The "Selected Readings in Computer Graphics 2007" consist of 34 articles selected from a total of 177 scientific publications contributed by all institutions of the INI-GraphicsNet. All articles previously appeared in various scientific books, journals, conferences and workshops, and are reprinted with permission of the respective copyright holders. The publications had to undergo a thorough review process by internationally leading experts and established technical societies. Therefore, the Selected Readings should give a fairly good and detailed overview of the scientific developments in the INI-GraphicsNet in the year 2007. They are published by Professor José Luis Encarnação, the director of the board of the INI-GraphicsNet Stiftung and Professor Dieter W. Fellner, the director of Fraunhofer Institute for Computer Graphics Research IGD in Darmstadt, the largest member of the INI-GraphicsNet.

The International Network of Institutions for advanced education, training and R&D in Computer Graphics technology, systems and applications (INI-GraphicsNet) is the largest research network worldwide entirely dedicated to the field of Computer Graphics. The "Selected Readings in Computer Graphics 2007" consist of 34 articles selected from a total of 177 scientific publications contributed by all institutions of the INI-GraphicsNet. All articles previously appeared in various scientific books, journals, conferences and workshops, and are reprinted with permission of the respective copyright holders. The publications had to undergo a thorough review process by internationally leading experts and established technical societies. Therefore, the Selected Readings should give a fairly good and detailed overview of the scientific developments in the INI-GraphicsNet in the year 2007. They are published by Professor José Luis Encarnação, the director of the board of the INI-GraphicsNet Stiftung and Professor Dieter W. Fellner, the director of Fraunhofer Institute for Computer Graphics Research IGD in Darmstadt, the largest member of the INI-GraphicsNet.

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.

Skala, Vaclav (Ed.): Journal of WSCG Vol. 16 No. 1-3, 2008. Proceedings. Plzen: University of West Bohemia, 2008, pp. 121-133

We present the Combined B-rep (cB-rep) as a multiresolution data structure suitable for interactive modeling and visualization of models composed of both free-form and polygonal parts. It is based on a half-edge data structure combined with Catmull/Clark subdivision surfaces. In addition to displaying the curved parts of the surface at an adaptive level-of-detail, the control mesh itself can be changed interactively at runtime using Euler operators. The tessellation of changed parts of the mesh is incrementally updated in real time. All changes in the mesh are logged, so that a complete undo/redo mechanism can be provided. We introduce Euler macros as a grouping mechanism for Euler operator sequences. The macro dependency graph, a directed acyclic graph, can be used for creating progressively increasing resolutions of the control mesh, and to guide the view-dependent refinement (pcB-rep). We consider Progessive Combined B-reps to be of use for data visualization and interactive 3D modeling, as well as a compact representation of synthetic 3D models.

Ashley, Michael (Ed.) et al.: VAST 2008. Proceedings. Aire-la-Ville: Eurographics Association, 2008, pp. 125-132

It is still a big technical problem to establish a relation between a shape and its meaning in a sustainable way. We present a solution with a markup method that allows to label parts of a 3D object in a similar way to labeling parts of a hypertext. A 3D-markup can serve both as hyperlink and as link anchor, which is the key to bi-directional linking between 3D objects and web documents. Our focus is on a sustainable 3D software infrastructure for application scenarios ranging from e-mail and internet over authoring and browsing semantic networks to interactive museum presentations. We demonstrate the workflow and the effectiveness of our tools by re-doing the Arrigo 3D showcase. We are working towards a "best practice" example for information modeling in cultural heritage

Institute of Electrical and Electronics Engineers (IEEE): IEEE Virtual Reality 2008. Proceedings [DVD-ROM] : VR '08. Los Alamitos, Calif.: IEEE Computer Society, 2008, Video 35 MB; Poster 1 p.

The DAVE is an immersive projection environment, a foursided CAVE. DAVE stands for "definitely affordable virtual environment". "Affordable" means that by mostly using standard hardware components we can greatly reduce costs compared to other commercial systems. We show the hardware setup and some applications in the accompanying video. In 2005 we buildt a new version of our DAVE at the University of Technology in Graz, Austria. Room restrictions motivated a new compact design to optimally use the available space. The back projection material with a custom shape is streched to the wooden frame to provide a flat surface without ripples.

IEEE Computer Graphics and Applications, Vol.28 (2008), 3, pp. 48-57

By combining two previously unrelated techniques - semantic markup in a scene-graph and generative modeling - a new framework retains semantic information until late in the rendering pipeline. This is a crucial prerequisite for achieving enhanced visualization effects and interactive behavior that doesn't compromise interactive frame rates. The proposed system creates interactive 3D visualizations from 2D geospatial databases in the domain of utility companies' underground infrastructure, creating urban models based on the companies' real-world data. The system encodes the 3D models in a scene-graph that mixes visual models with semantic markup that interactively filters and styles the models. The actual graphics primitives are generated on the fly by scripts that are attached to the scene-graph nodes.

Ambient Intelligence bezeichnet insbesondere ein neues Paradigma der Interaktion zwischen Dem Menschen und seiner Alltagsumgebung. Betrachtet man AmI-Umgebungen näher, kann festgestellt werden, dass die Anzahl elektronischer Geräte und deren funktionaler Komplexität ständig wächst. Dabei ist der Nutzer mit der Bedienung und Kontrolle der Technik überfordert. Viele Geräte besitzen aufgrund der Miniaturisierung eine umständliche und eingeschränkte Bedienmöglichkeit. Dies stellt neben der wachsenden Komplexität ein weiteres Problem für die Mensch-Umgebungs-Interaktion dar. Die Akzeptanz der Technologie und damit der Erfolg des AmI-Paradigmas hängt wesentlich von einer intuitiven Interaktion ab. Damit der Nutzer sich nicht in Fülle der Technik hilflos verliert, werden intuitive Bedienungskonzepte benötigt. Deshalb fokussiert diese Arbeit auf den Forschungsbereich der Assistenz zur ganzheitlichen und konfliktfreien Interaktion in adaptiven Umgebungen. Die Fragestellungen hierzu lauten zum einen, wie der Nutzer in solchen Umgebungen mit so einer großen Anzahl von komplexen Systemen interagieren wird. Zum anderen wie interagiert der Nutzer in einer unbekannten Umgebung mit einer Technik, welche wie "Strom, Wasser und Telefon" allgegenwärtig ist und zugleich "unsichtbar im Hintergrund verschwindet"? Die wichtigste Fragestellung dieser Arbeit lautet jedoch wie der Nutzer Geräte manuell auswählen kann ohne technische Informationen über die Infrastruktur zu haben? Vertiefend und im Zusammenhang mit der Behandlung der oben skizzierten Randbedingungen liefert diese Dissertation folgende wesentliche Beiträge zu den Gebieten Domainanalyse und Ontologien, Kontextbewußtsein sowie Mensch-Umgebungs-Interaktion.

Linsen, Lars (Ed.) et al.: Visualization in Medicine and Life Sciences. Berlin; Heidelberg; New York: Springer, 2008. (Mathematics and Visualization), pp. 257-274

Based on the results of an interdisciplinary research project the paper addresses the embedding of knowledge about the function of different parts/structures of a macro molecule (protein, DNA, RNA) directly into the 3D model of this molecule. Thereby the 3D visualization becomes an important user interface component when accessing domain-specific knowledge - similar to a web browser enabling its users to access various kinds of information. In the prototype implementation - named Biobrowser - various information related to bio-research is managed by a database using a fine-grain access control. This also supports restricting the access to parts of the material based on the user privileges. The database is supplied by a SOAP web service so that is it possible (after identifying yourself by a login procedure of course) to query, to change, or to add some information remotely by using the 3D model of the molecule. All these actions are performed on sub structures of the molecules. These can be selected either by an easy query language or by just picking them in the 3D model with the mouse.

Association for Computing Machinery (ACM): ACM Symposium on Applied Computing 2008. Proceedings : SAC 2008. New York: ACM Press, 2008, pp. 1197-1201

We systematically evaluate a recently proposed method for unsupervised discrimination power analysis for feature selection and optimization in multimedia applications. A series of experiments using real and synthetic benchmark data is conducted, the results of which indicate the suitability of the method for unsupervised feature selection and optimization. We present an approach for generating synthetic feature spaces of varying discrimination power, modelling main characteristics from real world feature vector extractors. A simple, yet powerful visualization is used to communicate the results of the automatic analysis to the user.

Mohler, Betty J. (Ed.) et al.: Virtual Environments 2008. Posters. Aire-la-Ville: Eurographics Association, 2008, pp. 5-8

We present several novel ways of interaction and navigation in virtual worlds. Using the optical tracking system of our four-sided Definitely Affordable Virtual Environment (DAVE), we designed and implemented navigation and movement controls using the user's gestures and postures. Our techniques are more natural and intuitive than a standard 3D joystick-based approach, which compromises the immersion's impact.

International Committee for Documentation of Cultural Heritage (CIPA): CIPA 2007 : Heritage Documentation [online]. [cited 06 March 2008] Available from: http://cipa.icomos.org/index.php?id=393#top 2008, 6 p.

A robust fitting and reconstruction algorithm has to cope with two major problems. First of all it has to be able to deal with noisy input data and outliers. Furthermore it should be capable of handling multiple data set mixtures. The decreasing exponential approach is robust towards outliers and multiple data set mixtures. It is able to fit a parametric model to a given point cloud. As parametric models use a description which may not only contain a generative shape but information about the inner structure of an object, the presented approach can enrich measured data with an ideal description. This technique offers a wide range of applications.

Spencer, Stephen N. (Ed.): Proceedings WEB3D 2008 : 13th International Symposium on 3D Web Technology. New York: ACM Press, 2008, pp. 75-81

Scripting techniques are used in various contexts. The field of application ranges from layout description languages (PostScript), user interface description languages (XUL) and classical scripting languages (JavaScript) to action nodes in scene graphs (VRMLScript) and web-based desktop applications (AJAX). All these applications have an increase of scripted components in common - especially in computer graphics. As the interpretation of a geometric script is computationally more intensive than the handling of static geometry, optimization techniques, such as justin- time compilation, are of great interest. Unfortunately, scripting languages tend to support features such as higher order functions or self-modification, etc. These language characteristic are difficult to compile into machine/byte-code. Therefore, we present a hybrid approach: an interpreter with an integrated compiler. In this way we speed up the script evaluation without having to remove any language features e.g. the possibility of self-modifications. We demonstrate its usage at XGML - a dialect of the generative modeling language GML, which is characterized by its dynamic behavior.

ACM Journal on Computing and Cultural Heritage, Vol.1 (2008), 2, 20 pp.

The current methods to describe the shape of three-dimensional objects can be classified into two groups: methods following the composition of primitives approach and descriptions based on procedural shape representations. As a 3D acquisition device returns an agglomeration of elementary objects (e.g. a laser scanner returns points), the model acquisition pipeline always starts with a composition of primitives. Due to the semantic information carried with a generative description, a procedural model provides valuable metadata that make up the basis for digital library services: retrieval, indexing, and searching. An important challenge in computer graphics in the field of cultural heritage is to build a bridge between the generative and the explicit geometry description combining both worlds-the accuracy and systematics of generative models with the realism and the irregularity of real-world data. A first step towards a semantically enriched data description is a reconstruction algorithm based on decreasing exponential fitting. This approach is robust towards outliers and multiple dataset mixtures. It does not need a preceding segmentation and is able to fit a generative shape template to a point cloud identifying the parameters of a shape.

Ioannides, Marinos (Ed.) et al.: Digital Heritage. Proceedings of the 14th International Conference on Virtual Systems and Multimedia. Project Papers : VSMM 2008, pp. 334-340

The need to analyze and visualize differences of very similar objects arises in many research areas: mesh compression, scan alignment, nominal/actual value comparison, quality management, and surface reconstruction to name a few. Although the problem to visualize some distances may sound simple, the creation of a good scene setup including the geometry, materials, colors, and the representation of distances is challenging. Our contribution to this problem is an application which optimizes the work-flow to visualize distances. We propose a new classification scheme to group typical scenarios. For each scenario we provide reasonable defaults for color tables, material settings, etc. Completed with predefined file exporters, which are harmonized with commonly used rendering and viewing applications, the presented application is a valuable tool. Based on web technologies it works out-of-the-box and does not need any configuration or installation. All users who have to analyze and document 3D geometry will stand to benefit from our new application.

Luca, Joseph (Ed.) et al.: Proceedings of ED-Media 2008 : World Conference on Educational Multimedia, Hypermedia & Telecommunications [CD-ROM]. Chesapeake, 2008, pp. 5467-5472

The combination of scripting languages with web technologies offers many possibilities in teachings. This paper presents a scripting framework that consists of a Java and JavaScript engine and an included editor. It allows editing scripts and source code online, writing new applications, modifying existing applications and starting them from within the editor by a simple mouse click. This framework is a good basis for online tutorials. Included scripts that are ready to run are able to replace simple Java applets without drawbacks but with much more possibilities. Furthermore these scripts are perfect in different teaching scenarios: demo applications can be started via web browser and can be modified just in time. This modification can be done during lecture or within a drill-and-practice session. Examples in the context of computer graphics illustrate the usefulness of our framework in lectures.

One of the key problems of augmented reality is the tracking of the camera position and viewing direction in real-time. Current vision-based systems mostly rely on the detection and tracking of fiducial markers. Some markerless approaches exist, which are based on 3D line models or calibrated reference images. These methods require a high manual preprocessing work step, which is not applicable for the efficient development and design of industrial AR applications. The problem of the preprocessing overload is addressed by the development of vision-based tracking algorithms, which require a minimal workload of the preparation of reference data. A novel method for the automatic view-dependent generation of line models in real-time is presented. The tracking system only needs a polygonal model of a reference object, which is often available from the industrial construction process. Analysis-by-synthesis techniques are used with the support of graphics hardware to create a connection between virtual model and real model. Point-based methods which rely on optical flow-based template tracking are developed for the camera pose estimation in partially known scenarios. With the support of robust reconstruction algorithms a real-time tracking system for augmented reality applications is developed, which is able to run with only very limited previous knowledge about the scene. The robustness and real-time capability is improved with a statistical approach for a feature management system which is based on machine learning techniques.

Castelli, Donatella (Ed.) et al.: Foundations of Digital Libraries : Pre-Proceedings of the First International Workshop on "Digital Libraries Foundations", pp. 7-12

3D documents are an indispensable data type in many important application domains such as Computer Aided Design, Simulation and Visualization, and Cultural Heritage, to name a few. The 3D document type can represent arbitrarily complex information by composing geometrical, topological, structural, or material properties, among others. It often is integrated with meta data and annotation by the various application systems that produce, process, or consume 3D documents. We argue that due to the inherent complexity of the 3D data type in conjunction with and imminent pervasive usage and explosion of available content, there is pressing need to address key problems of the 3D data type. These problems need to be tackled before the 3D data type can be fully supported by Digital Library technology in the sense of a generalized document, unlocking its full potential. If the problems are addressed appropriately, the expected benefits are manifold and may lead to radically improved production, processing, and consumption of 3D content.

The International Network of Institutions for advanced education, training and R&D in Computer Graphics technology, systems and applications (INI-GraphicsNet) is the largest research network worldwide entirely dedicated to the field of Computer Graphics. The "Selected Readings in Computer Graphics 2006" consist of 29 articles selected from a total of 168 scientific publications contributed by all institutions of the INI-GraphicsNet. All articles previously appeared in various scientific books, journals, conferences and workshops, and are reprinted with permission of the respective copyright holders. The publications had to undergo a thorough review process by internationally leading experts and established technical societies. Therefore, the Selected Readings should give a fairly good and detailed overview of the scientific developments in the INI-GraphicsNet in the year 2006. They are published by Professor José Luis Encarnação, the director of the board of the INI-GraphicsNet Stiftung and Professor Dieter W. Fellner, the director of Fraunhofer Institute for Computer Graphics Research IGD in Darmstadt, the largest member of the INI-GraphicsNet.

The International Network of Institutions for advanced education, training and R&D in Computer Graphics technology, systems and applications (INI-GraphicsNet) is the largest research network worldwide entirely dedicated to the field of Computer Graphics. The "Selected Readings in Computer Graphics 2006" consist of 29 articles selected from a total of 168 scientific publications contributed by all institutions of the INI-GraphicsNet. All articles previously appeared in various scientific books, journals, conferences and workshops, and are reprinted with permission of the respective copyright holders. The publications had to undergo a thorough review process by internationally leading experts and established technical societies. Therefore, the Selected Readings should give a fairly good and detailed overview of the scientific developments in the INI-GraphicsNet in the year 2006. They are published by Professor José Luis Encarnação, the director of the board of the INI-GraphicsNet Stiftung and Professor Dieter W. Fellner, the director of Fraunhofer Institute for Computer Graphics Research IGD in Darmstadt, the largest member of the INI-GraphicsNet.

IEEE Instrumentation and Measurement Society: IEEE International Symposium on Intelligent Signal Processing : WISP 2007. Piscataway, NJ: IEEE Service Center, 2007, 6 p.

Line-of-sight (LOS) computation is important for interrogation of heightfield grids in the context of geo information and many simulation tasks like electromagnetic wave propagation and flight surveillance. Compared to searching the regular grid directly, more advanced data structures like a 2.5 d kd-tree offer better performance. We describe the definition of a 2.5 d kd-tree from the digital elevation model and its use for LOS computation on a point-reconstructed or bilinear-reconstructed terrain surface. For compact storage, we use a wavelet-like storage scheme which saves one half of the storage space without considerably compromising the runtime performance. We give an empirical comparison of both approaches on practical data sets which show the method of choice for CPU computation of LOS.

IEEE Computer Graphics and Applications, Vol.27 (2007), 3, pp. 70-76

The rapid evolution of information and communication technology has always been a source for challenging new research questions in computer science. The vision of the emerging research field of semantic 3D is to establish the notion of generalized 3D documents that are full members of the family of generalized documents. This means that access would be content-based rather than based on metadata. The purpose of this article is to highlight the research issues that impede the realization of this vision today. The seven research challenges include: (1) '3D data set' can have many meanings, (2) a sustainable 3D file format, (3) representation-independent stable 3D markup, (4) representation-independent 3D query operations, (5) documenting provenance and processing history, (6) consistency between shape and meaning, and (7) closing the semantic gap.

Arnold, David (Ed.) et al.: VAST 2007. Proceedings : The 8th International Symposium on Virtual Reality, Archaeology and Intelligent Cultural Heritage. Aire-la-Ville: Eurographics Association, 2007, pp. 39-46; 145 [Color Plate]

We describe first steps towards a suite of tools for CH professionals to set up and run digital exhibitions of cultural 3D artifacts in museums. Both the authoring and the presentation views shall finally be as easy to use as, e.g., Microsoft Powerpoint. But instead of separated slides our tool uses pre-defined 3D scenes, called "layouts", containing geometric objects acting as placeholders, called "drop targets". They can be replaced quite easily, in a drag-and-drop fashion, by digitized 3D models, and also by text and images, to customize and adapt a digital exhibition to the style of the real museum. Furthermore, the tool set contains easy-to-use tools for the rapid 3D modeling of simple geometry and for the alignment of given models to a common coordinate system. The technical innovation is that the tool set is not a monolithic application. Instead it is completely based on scripted designs, using the OpenSG scene graph engine and the GML scripting language. This makes it extremely flexible: Anybody capable of drag-and-drop can design 3D exhibitions. Anybody capable of GML scripting can create new designs. And finally, we claim that the presentation setup of our designs is "grandparent-compliant", meaning that it permits to the public audience the detailed inspection of beautiful cultural 3D objects without getting lost or feeling uncomfortable.

Schenk, Michael (Ed.): 10. IFF-Wissenschaftstage 2007. Tagungsband [CD-ROM] : 15 Jahre Fraunhofer IFF. Magdeburg: Fraunhofer IFF, 2007, VR-Teil, pp. 77-86

Der Artikel beschreibt die erfolgreiche Entwicklung eines stereoskopiefähigen Digitalprojektors nach Zielvorgaben speziell für die Bereiche VR/AR. Dabei wurde nicht von den vorhandenen Technologien ausgegangen um ein VR/AR System zusammenzustellen, sondern explizit Zielvorgaben für ein solches System entwickelt um die Vor- und Nachteile bekannter Technologien zu minimieren. Dies führte zur Entwicklung eines völlig neuen 3D Projektors.

Fröhlich, Bernd (Ed.) et al.: Virtual Environments 2007. IPT-EGVE 2007 : Short Papers and Posters. Aire-la-Ville: Eurographics Association, 2007, pp. 21-26

We present a novel stereoscopic projection system. It combines all the advantages of modern single-chip DLP technology - attractive price, great brightness, high contrast, superior resolution and color quality - with those of active stereoscopy: invariance to the orientation of the user and an image separation of nearly 100%. With a refresh rate of 60 Hz per eye (120 Hz in total) our system is flicker-free even for sensitive users. The system permits external projector synchronisation which allows to build up affordable stereoscopic multi-projector systems, e.g., for immersive visualisation.

Kovács, László (Ed.) et al.: Research and Advanced Technology for Digital Libraries. Proceedings : 11th European Conference, ECDL 2007. Berlin, Heidelberg, New York: Springer, 2007. (Lecture Notes in Computer Science (LNCS) 4675), pp. 518-521

The number of newly generated multimedia documents (e.g. music, e-learning material, or 3D-graphics) increases year by year. Today, the workflow in digital libraries focuses on textual documents only. Hence, considering content-based retrieval tasks, multimedia documents are not analyzed and indexed sufficiently. To facilitate content-based retrieval and browsing, it is necessary to introduce recent techniques for multimedia document processing into the workflow of nowadays digital libraries. In this short paper, we introduce the PROBADO-framework which will (a) integrate different types of content-repositories - each one specialized for a specific multimedia domain - into one seamless system, and (b) will add features available in text-based digital libraries (such as automatic annotation, full-text retrieval, or recommender services) to non-textual documents. Existing libraries will benefit from the framework since it extends existing technology for handling textual documents with features for dealing with the non-textual domain.

International Journal of Bioelectromagnetism, Vol.9 (2007), 4, pp. 237-244

The results of a self-paced Brain-Computer Interface (BCI) are presented which are based on the detection of senorimotor electroencephalogram rhythms during motor imagery. The participants were given the task of moving through a virtual model of the Austrian National Library by performing motor imagery. This work shows that five participants which were trained in a synchronous BCI could sucessfully perform the asynchronous experiment.

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.

IEEE Potentials, Vol.26 (2007), 4, pp. 38-43

Information technology applications in the field of cultural heritage include various disciplines of computer science. The work flow from archaeological discovery to scientific preparation demands multidisciplinary cooperation and interaction at various levels. This article describes the information technology pipeline from the computer science point of view. The description starts with the model acquisition. Computer vision algorithms are able to generate a raw three-dimensional (3-D) model using input data such as photos and scans. In the next step, computer graphics methods create an accurate, highlevel model description. Besides geometric information, each model needs semantic metadata to perform digital library tasks such as storage, markup, indexing, and retrieval. A structured repository of virtual artifacts completes the pipeline - at least from the computer science point of view.

Ercim News, (2007), 71, pp.43-44

The computer graphics tutorial CGTutorial was developed by the Institute of Computer Graphics and Knowledge Visualization at Graz University of Technology in Austria. It combines a scripting engine and a development environment with Java-based Web technology. The result is a flexible framework which allows algorithms to be developed and studied without the need to install libraries or set up compiler configurations. Together with already written example scripts, the framework is ready to use. Each example script is a small runnable demonstration application that can be started directly within a browser. Using a scripting engine that interprets Java and JavaScript on a client, the demos can be modified and analysed by the user and then restarted. This combination of scripting engines and Web technology is thus a perfect environment for blended learning scenarios.

IEEE Potentials, Vol.26 (2007), 1, pp. 26-30

In this article, we present two algorithms for precise collision detection between two potentially colliding objects. The first one uses axis-aligned bounding boxes (AABB) and is a typical representative of a computational geometry algorithm. The second one uses spherical distance fields originating in image processing. Both approaches address the following challenges of collision detection algorithms: just in time, little resources, inclusive etc. Thus both approaches are scalable in the information they give in collision determination and the analysis up to a fixed refinement level, the collision time depends on the granularity of the bounding volumes and it is also possible to estimate the time bounds for the collision test tightly.

Lensch, Hendrik P. A. (Ed.) et al.: Vision, Modeling, and Visualization 2007. Proceedings : VMV 2007. Saarbrücken: Max Planck Institut für Informatik, 2007, pp. 161-169

This article focuses on algorithms for fast computation of the Euclidean distance between a query point and a subdivision surface. The analyzed algorithms include uniform tessellation approaches, an adaptive evalution technique, and an algorithm using Bézier conversions. These methods are combined with a grid hashing structure for space partitioning to speed up their runtime. The results show that a pretessellated surface is sufficient for small models. Considering the runtime, accuracy and memory usage an adaptive on-the-fly evaluation of the surface turns out to be the best choice.

Es werden verschiedene Verfahren zur Analyse von Bilddaten des kardiovaskulären Systems behandelt. Damit wird eine Verbesserung sowohl der Diagnose als auch der Planung von eventuell notwendigen Eingriffen erreicht. Die beschriebenen Verfahren zeichnen sich durch eine hohe Automatisierung und Reproduzierbarkeit der Analyseergebnisse sowie ihre klinische Anwendbarkeit aus. Augenmerk wird vor allem auf die auf der Oberfläche des Herzens liegenden Herzkranzgefäße und die den Hauptteil des Herzens bildenden Kavitäten - das linke und rechte Ventrikel gelegt. Hier werden verschiedene im Rahmen dieser Arbeit entwickelte, neue Segmentierungs- und Analyseverfahren vorgestellt und diskutiert. Im Falle der Herzkranzgefäße sind das trackingbasierte Segmentierungsansätze, die die Basis bilden für eine Analyse des Gefäßes hinsichtlich - der Detektion und Vermessung von Stenosen - des Vorhandenseins von harten Arterienverkalkungen - der Zusammensetzung des umliegenden Gewebes Desweiteren wird ein Verfahren vorgestellt, das es ermöglicht, die damit erreichten Ergebnisse mit der Koronarangiographie - dem Gold-Standard - zu vergleichen. Für eine angepaßte Präsentation der Analyseergebnisse werden speziell entwickelte Verfahren für deren optimale Visualisierung als auch die der Bilddaten selbst vorgestellt. Letztere betreffend wird ein automatisches Verfahren eingeführt, mit dessen Hilfe sich Strukturen wie der Brustkorb ausmaskieren lassen, die die direkte Sicht auf das Herz stören. Für die Analyse von linkem (LV) und rechtem Ventrikel (RV) werden automatisierte Segmentierungsverfahren vorgestellt, aus deren Ergebnis sich die die Dynamik der Ventrikel beschreibenden physikalischen Parameter ableiten lassen. Für das LV wird eine umfassende, automatische und detaillierte Analyse der Wandbewegung, Wanddickenzunahme und Volumenänderung vorgestellt. Als neuer Deskriptor für die Dynamik wird die Asynchronität eingeführt. Die für das LV entwickelten Analyseverfahren werden auf das RV übertragen und ermöglichen so eine ganz neue Qualität dessen Analyse. Die Präsentation der berechneten Parameter erfolgt in einer standardisierten Weise entsprechend den Empfehlungen der American Heart Association. Als Erweiterung dieser Darstellungsmöglichkeit wird die direkte Visualisierung dieser Größen zusammen mit einem 3D-Rendering des LV eingeführt. Dies fließt ein in eine kombinierte Darstellung von dynamischen Parametern und Infarktbereichen des Herzens. Letztere werden zudem automatisch quantifiziert. Die wesentlichen Fortschritte dieser Arbeit sind: 1. die Entwicklung zweier neuer trackingbasierter Algorithmen für die Segmentierung von Koronararterien in kontratverstärkten CT-Daten, 2. die Einführung neuer Visualisierungsmethoden für die Präsentation der Ergebnisse der Koronaranalyse, 3. die Schaffung direkter Vergleichsmöglichkeiten zwischen CT-Angiographie und konventioneller Angiographie, 4. die Kombination bestehender Segmentierungstechniken mit anatomischer Kenntnis für eine automatisierte Extraktion von linkem und rechtem Ventrikel, 5. die Etablierung von umfassenden Analyseverfahren für die Dynamik des linken Ventrikels, 6. die erstmalige Anwendung dieser Ansätze auf die Dynamik des rechten Ventrikels, 7. die Einführung eines das asynchrone Verhalten von Bereichen des Ventrikels beschreibenden neuen Parameters in die LV-Analyse und 8. die Erweiterung der Diagnostik von Infarktbereichen um eine automatische Narbenquantifizierung und neue Visualisierungsmethoden.

Es werden verschiedene Verfahren zur Analyse von Bilddaten des kardiovaskulären Systems behandelt. Damit wird eine Verbesserung sowohl der Diagnose als auch der Planung von eventuell notwendigen Eingriffen erreicht. Die beschriebenen Verfahren zeichnen sich durch eine hohe Automatisierung und Reproduzierbarkeit der Analyseergebnisse sowie ihre klinische Anwendbarkeit aus. Augenmerk wird vor allem auf die auf der Oberfläche des Herzens liegenden Herzkranzgefäße und die den Hauptteil des Herzens bildenden Kavitäten - das linke und rechte Ventrikel gelegt. Hier werden verschiedene im Rahmen dieser Arbeit entwickelte, neue Segmentierungs- und Analyseverfahren vorgestellt und diskutiert. Im Falle der Herzkranzgefäße sind das trackingbasierte Segmentierungsansätze, die die Basis bilden für eine Analyse des Gefäßes hinsichtlich - der Detektion und Vermessung von Stenosen - des Vorhandenseins von harten Arterienverkalkungen - der Zusammensetzung des umliegenden Gewebes Desweiteren wird ein Verfahren vorgestellt, das es ermöglicht, die damit erreichten Ergebnisse mit der Koronarangiographie - dem Gold-Standard - zu vergleichen. Für eine angepaßte Präsentation der Analyseergebnisse werden speziell entwickelte Verfahren für deren optimale Visualisierung als auch die der Bilddaten selbst vorgestellt. Letztere betreffend wird ein automatisches Verfahren eingeführt, mit dessen Hilfe sich Strukturen wie der Brustkorb ausmaskieren lassen, die die direkte Sicht auf das Herz stören. Für die Analyse von linkem (LV) und rechtem Ventrikel (RV) werden automatisierte Segmentierungsverfahren vorgestellt, aus deren Ergebnis sich die die Dynamik der Ventrikel beschreibenden physikalischen Parameter ableiten lassen. Für das LV wird eine umfassende, automatische und detaillierte Analyse der Wandbewegung, Wanddickenzunahme und Volumenänderung vorgestellt. Als neuer Deskriptor für die Dynamik wird die Asynchronität eingeführt. Die für das LV entwickelten Analyseverfahren werden auf das RV übertragen und ermöglichen so eine ganz neue Qualität dessen Analyse. Die Präsentation der berechneten Parameter erfolgt in einer standardisierten Weise entsprechend den Empfehlungen der American Heart Association. Als Erweiterung dieser Darstellungsmöglichkeit wird die direkte Visualisierung dieser Größen zusammen mit einem 3D-Rendering des LV eingeführt. Dies fließt ein in eine kombinierte Darstellung von dynamischen Parametern und Infarktbereichen des Herzens. Letztere werden zudem automatisch quantifiziert. Die wesentlichen Fortschritte dieser Arbeit sind: 1. die Entwicklung zweier neuer trackingbasierter Algorithmen für die Segmentierung von Koronararterien in kontratverstärkten CT-Daten, 2. die Einführung neuer Visualisierungsmethoden für die Präsentation der Ergebnisse der Koronaranalyse, 3. die Schaffung direkter Vergleichsmöglichkeiten zwischen CT-Angiographie und konventioneller Angiographie, 4. die Kombination bestehender Segmentierungstechniken mit anatomischer Kenntnis für eine automatisierte Extraktion von linkem und rechtem Ventrikel, 5. die Etablierung von umfassenden Analyseverfahren für die Dynamik des linken Ventrikels, 6. die erstmalige Anwendung dieser Ansätze auf die Dynamik des rechten Ventrikels, 7. die Einführung eines das asynchrone Verhalten von Bereichen des Ventrikels beschreibenden neuen Parameters in die LV-Analyse und 8. die Erweiterung der Diagnostik von Infarktbereichen um eine automatische Narbenquantifizierung und neue Visualisierungsmethoden.

In computer graphics and robotics a lot of different mathematical systems like vector algebra, homogenous coordinates, quaternions or dual quaternions are used for different applications. Now it seems that a change of paradigm is lying ahead of us based on Conformal Geometric Algebra unifying all of these different approaches in one mathematical system. Conformal Geometric Algebra is a very powerful mathematical framework. Due to its geometric intuitiveness, compactness and simplicity it is easy to develop new algorithms. Algorithms based on Conformal Geometric Algebra lead to enhanced quality, a reduction of development time, better understandable and better maintainable solutions. Often a clear structure and greater elegance results in lower runtime performance. However, it will be shown that algorithms based on Conformal Geometric Algebra can even be faster than conventional algorithms. The main contribution of this thesis is the geometrically intuitive and - nevertheless - efficient algorithm for a computer animation application, namely an inverse kinematics algorithm for a virtual character. This algorithm is based on an embedding of quaternions in Conformal Geometric Algebra. For performance reasons two optimization approaches are used in a way to make the application now three times faster than the conventional solution. With these results we are convinced that Geometric Computing using Conformal Geometric Algebra will become more and more fruitful in a great variety of applications in computer graphics and robotics.

Die ständig wachsende Menge an verfügbaren digitalen Daten erfordert neuartige Methoden, die einen gezielten Zugriff auf relevante Information ermöglichen. Eine zentrale Rolle spielt in diesem Zusammenhang die automatische Erschließung bildlicher Information in digitalen Bilddaten. Der klassische Ansatz - die manuelle Annotation des Bildinhaltes mittels alphanumerischer Texte - hat sich in der Vergangenheit als zu fehleranfällig und zu kostenintensiv erwiesen. Im Rahmen dieser Arbeit wird ein alternativer Ansatz entwickelt, der es ermöglicht, große Mengen von digitalen Bilddaten mittels merkmalsbasierter Verfahren zu erschließen. Dies geschieht unter der Annahme, dass das zugrundeliegende Bildmaterial weder aufgrund seines Erscheinungsbildes, noch aufgrund seiner Bedeutung irgendeiner Einschränkung unterliegt. Zunächst wird ein allgemeingültiges Modell für die merkmalsbasierte Suche nach visuellen Inhalten in digitalen Bildern definiert. Dieses Modell stellt den formalen Rahmen für die Entwicklung und Kombinierung neuartiger Algorithmen zur Merkmalsextraktion und -indexierung dar. Das Modell ermöglicht eine inhaltsbasierte Bildsuche auf der Basis eines Systems mit einheitlicher Architektur und standardisierten Schnittstellen. Ein solches System kann durch die Entwicklung einzelner anwendungsspezifischer Bausteine für eine bestimmte Problemstellung erweitert werden. Startpunkt für die Entwicklung eines Algorithmus zur Merkmalsextraktion ist die sinnvolle Interpretation der Farben einzelner diskreter Bildpunkte. Der Mensch unterscheidet im Gegensatz zur technischen Darstellung nur zwischen einer handvoll verschiedener Farben. Daher wird im Rahmen dieser Arbeit die neuartige Farbrepräsentation vorgestellt, die die Farbinformation eines Bildes auf der Basis von - für den Menschen bedeutungsvollen - Farbnamen zugänglich macht. Das zugrundeliegende mathematische Gerüst ermöglicht einen einfachen und schnellen Vergleich von Farben. Eine solche Interpretation von Farbinformation kann nahezu für jede Aufgabe im Bereich der digitalen Bildverarbeitung nutzbringend eingesetzt werden. Auf dieser Farbrepräsentation aufbauend werden einige universelle Extraktionsalgorithmen vorgestellt, die gewisse visuelle Aspekte eines digitalen Bildes kompakt beschreiben. Große Datenmengen bedingen entsprechend lange Verarbeitungszeiten bei der Suche nach Information. Daher wird im letzten Teil der Arbeit ein Indexierungsverfahren vorgestellt, dass die proportionale Beziehung zwischen Datenmenge und Verarbeitungszeit aufbricht. Das Indexierungsverfahren basiert auf der Lokaliserung der Suche in der unmittelbaren Umgebung der Suchanfrage im Merkmalsraum. Durch das Eingrenzen des Suchraums kann eine signifikante Beschleunigung der Suche erreicht werden. Da ein solches Verfahren immanent mit einer gewissen Ungenauigkeit behaftet ist, werden experimentelle Ergebnisse präsentiert, die den Nutzen des Verfahrens im praktischen Einsatz dokumentieren.

Die vorliegende Arbeit beschreibt den Einsatz von PC Clustern für die interaktive Visualisierung dreidimensionaler polygonaler Modelle. Ziel der Arbeit war es, durch Bündelung der Leistung vieler Rechner die Qualität der Darstellung zu verbessern. Darüber hinaus sollte die Entwicklung neuer Cluster basierter graphischer Anwendungen vereinfacht werden. Es wird gezeigt, wie ein Szenengraphsystem erweitert werden muss, um eine verteilte Bildberechnung in einem Cluster zu ermöglichen. Hierfür wurden verschiedene Synchronisationsmechanismen untersucht und neue Netzwerkprotokolle entwickelt. Auf der Basis des verteilten Szenengraphen wurden verschiedene Parallelisierungsstrategien erforscht und optimierte Verfahren für die parallele Berechnung des Bildraums und die parallele Berechnung der Szene vorgestellt. Mit Hilfe der entwickelten Verfahren lassen sich beliebige zusammengesetzte Projektionssysteme wie z.B Tiled Display, Workbench oder Cave sehr effizient mit Hilfe eines PC-Clusters betreiben. Weiterhin ist es möglich, auch sehr große Szenen mit hohen Bildwiederholraten anzuzeigen.