Liste der Fachpublikationen

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Becker, Meike; Hansen, Stefan; Wesarg, Stefan; Sakas, Georgios

Path Planning for Multi-port Lateral Skull Base Surgery Based on First Clinical Experiences

2014

Erdt, Marius (Ed.) et al.: Clinical Image-Based Procedures. Translational Research in Medical Imaging : Second International Workshop, CLIP 2013. Held in Conjunction with MICCAI 2013. Berlin, Heidelberg, New York: Springer, 2014. (Lecture Notes in Computer Science (LNCS) 8361), pp. 23-30

International Workshop on Clinical Image-based Procedures (CLIP) <2, 2013, Nagoya, Japan>

Our research project investigates a multi-port minimally-traumatic approach for lateral skull base surgery, where the surgical target shall be reached through up to three drill canals. For this purpose, an accurate path planning is crucial. In the present work, we propose a semiautomatic path planning approach for multi-port minimally-traumatic lateral skull base surgery. The best path combinations are automatically determined by optimizing the angles and distance buffers of the drill canals. We compare the automatically computed path combinations for 20 data sets to those selected manually by two different clinicians. The experiments prove that we can adequately reproduce the clinicians' choice.

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Becker, Meike; Sakas, Georgios (Betreuer); Fellner, Dieter W. (Betreuer); Schipper, Jörg (Betreuer)

Patientenspezifische Planung für die Multi-Port Otobasischirurgie

2014

Darmstadt, TU, Diss., 2014

Bisher werden Operationen im Bereich der seitlichen Schädelbasis (Otobasis) stark invasiv durchgeführt. Um die Traumatisierung für den Patienten zu reduzieren, wird seit kurzem ein Multi-Port Ansatz untersucht, bei dem bis zu drei dünne Bohrkanäle von der Schädeloberfläche bis zum Operationsziel angelegt werden. Aufgrund der Minimalinvasivität des neuen Eingriffs ist die visuelle Kontrolle durch den Chirurgen nicht mehr möglich. Somit ist eine präzise patientenspezifische Planung basierend auf Bilddaten zwingend erforderlich. Der Fokus dieser Arbeit liegt daher auf der Planung eines Multi-Port Eingriffs basierend auf patientenspezifischen Modellen. Zur Generierung dieser Modelle habe ich zunächst Methoden für die Segmentierung der Risikostrukturen der Otobasis in Computertomographiedaten entwickelt. Die Herausforderungen dabei sind die geringe Größe der Strukturen, der fehlende Kontrast zum umliegenden Gewebe sowie die zum Teil variierende Form und Bildintensität. Daher schlage ich die Verwendung eines modellbasierten Ansatzes - das Probabilistic Active Shape Model - vor. Dieses habe ich für die Risikostrukturen der Otobasis adaptiert und intensiv evaluiert. Dabei habe ich gezeigt, dass die Segmentierungsgenauigkeit im Bereich der manuellen Segmentierungsgenauigkeit liegt. Ferner habe ich Methoden für die automatische Planung der Bohrkanäle basierend auf den durch die Segmentierung gewonnenen patientenspezifischen Modellen entwickelt. Die Herausforderung hierbei ist, dass der Multi-Port Eingriff noch nicht im klinischen Einsatz ist und somit Erfahrung mit der neuen Strategie fehlt. Daher wurde zunächst ein Planungstool zur Berechnung einer Menge von zulässigen Bohrkanälen entwickelt und die manuelle Auswahl einer Bohrkanalkombination ermöglicht. Damit haben zwei Ärzte eine erste Machbarkeitsanalyse durchgeführt. Die so gewonnene Erfahrung und Datenbasis habe ich formalisiert und ein Modell für die automatische Planung einer Bohrkanalkombination abgeleitet. Die Evaluation zeigt, dass auf diese Weise Bohrkanalkombinationen vergleichbar mit der manuellen Wahl der Ärzte berechnet werden können. Damit ist erstmals die computergestützte Planung eines Multi-Port Eingriffs an der Otobasis möglich.

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Steger, Sebastian; Jung, Florian; Wesarg, Stefan

Personalized Articulated Atlas with a Dynamic Adaptation Strategy for Bone Segmentation in CT- or CT/MR Head & Neck Images

2014

Ourselin, Sébastien (Ed.) et al.: Medical Imaging 2014: Image Processing : Progress in Biomedical Optics and Imaging Vol. 15 No. 35. Bellingham: SPIE Press, 2014. (Proceedings of SPIE 9034), 6 p.

SPIE Medical Imaging Symposium <2014, San Diego, CA, USA>

This paper presents a novel segmentation method for the joint segmentation of individual bones in CT- or CT/MR- head & neck images. It is based on an articulated atlas for CT images that learned the shape and appearance of the individual bones along with the articulation between them from annotated training instances. First, a novel dynamic adaptation strategy for the atlas is presented in order to increase the rate of successful adaptations. Then, if a corresponding CT image is available the atlas can be enriched with personalized information about shape, appearance and size of the individual bones from that image. Using mutual information, this personalized atlas is adapted to an MR image in order to propagate segmentations. For evaluation, a head & neck bone atlas created from 15 manually annotated training images was adapted to 58 clinically acquired head & neck CT datasets. Visual inspection showed that the automatic dynamic adaptation strategy was successful for all bones in 86% of the cases. This is a 22% improvement compared to the traditional gradient descent based approach. In leave-one-out cross validation manner the average surface distance of the correctly adapted items was found to be 0.68 mm. In 20 cases corresponding CT/MR image pairs were available and the atlas could be personalized and adapted to the MR image. This was successful in 19 cases.

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Ackermann, Jens; Goesele, Michael (Betreuer); Klein, Reinhard (Betreuer)

Photometric Reconstruction from Images: New Scenarios and Approaches for Uncontrolled Input Data

2014

Darmstadt, TU, Diss., 2014

The changes in surface shading caused by varying illumination constitute an important cue to discern fine details and recognize the shape of texture less objects. Humans perform this task subconsciously, but it is challenging for a computer because several variables are unknown and intermix in the light distribution that actually reaches the eye or camera. In this work, we study algorithms and techniques to automatically recover the surface orientation and reflectance properties from multiple images of a scene. Photometric reconstruction techniques have been investigated for decades but are still restricted to industrial applications and research laboratories. Making these techniques work on more general, uncontrolled input without specialized capture setups has to be the next step but is not yet solved. We explore the current limits of photometric shape recovery in terms of input data and propose ways to overcome some of its restrictions. Many approaches, especially for non-Lambertian surfaces, rely on the illumination and the radiometric response function of the camera to be known. The accuracy such algorithms are able to achieve depends a lot on the quality of an a priori calibration of these parameters. We propose two techniques to estimate the position of a point light source, experimentally compare their performance with the commonly employed method, and draw conclusions which one to use in practice. We also discuss how well an absolute radiometric calibration can be performed on uncontrolled consumer images and show the application of a simple radiometric model to re-create night-time impressions from color images. A focus of this thesis is on Internet images which are an increasingly important source of data for computer vision and graphics applications. Concerning reconstructions in this setting we present novel approaches that are able to recover surface orientation from Internet webcam images. We explore two different strategies to overcome the challenges posed by this kind of input data. One technique exploits orientation consistency and matches appearance profiles on the target with a partial reconstruction of the scene. This avoids an explicit light calibration and works for any reflectance that is observed on the partial reference geometry. The other technique employs an outdoor lighting model and reflectance properties represented as parametric basis materials. It yields a richer scene representation consisting of shape and reflectance. This is very useful for the simulation of new impressions or editing operations, e.g. relighting. The proposed approach is the first that achieves such a reconstruction on webcam data. Both presentations are accompanied by evaluations on synthetic and real-world data showing qualitative and quantitative results. We also present a reconstruction approach for more controlled data in terms of the target scene. It relies on a reference object to relax a constraint common to many photometric stereo approaches: the fixed camera assumption. The proposed technique allows the camera and light source to vary freely in each image. It again avoids a light calibration step and can be applied to non-Lambertian surfaces. In summary, this thesis contributes to the calibration and to the reconstruction aspects of photometric techniques. We overcome challenges in both controlled and uncontrolled settings, with a focus on the latter. All proposed approaches are shown to operate also on non-Lambertian objects.

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Policy Modeling Methodologies

2014

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

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

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Bender, Jan; Koschier, Dan; Charrier, Patrick; Weber, Daniel

Position-based Simulation of Continuous Materials

2014

Computers & Graphics, Vol.44 (2014), pp. 1-10

We introduce a novel fast and robust simulation method for deformable solids that supports complex physical effects like lateral contraction, anisotropy or elastoplasticity. Our method uses a continuum-based formulation to compute strain and bending energies for two- and three-dimensional bodies. In contrast to previous work, we do not determine forces to reduce these potential energies, instead we use a position-based approach. This combination of a continuum-based formulation with a position-based method enables us to keep the simulation algorithm stable, fast and controllable while providing the ability to simulate complex physical phenomena lacking in former position-based approaches. We demonstrate how to simulate cloth and volumetric bodies with lateral contraction, bending, plasticity as well as anisotropy and proof robustness even in case of degenerate or inverted elements. Due to the continuous material model of our method further physical phenomena like fracture or viscoelasticity can be easily implemented using already existing approaches. Furthermore, a combination with other geometrically motivated methods is possible.

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Santos, Pedro; Peña Serna, Sebastian; Stork, André; Fellner, Dieter W.

The Potential of 3D Internet in the Cultural Heritage Domain

2014

Ioannides, Marinos (Ed.) et al.: 3D Research Challenges in Cultural Heritage : A Roadmap in Digital Heritage Preservation. Berlin, Heidelberg, New York: Springer, 2014. (Lecture Notes in Computer Science (LNCS) 8355), pp. 1-17

Europe is rich in cultural heritage but unfortunately much of the tens of millions of artifacts remain in archives. Many of these resources have been collected to preserve our history and to understand their historical context. Nevertheless, CH institutions are neither able to document all the collected resources nor to exhibit them. Additionally, many of these CH resources are unique, and will be on public display only occasionally. Hence, access to and engagement with this kind of cultural resources is important for European culture and the legacy of future generations. However, the technology needed to economically mass digitize and annotate 3D artifacts in analogy to the digitization and annotation of books and paintings has yet to be developed. Likewise approaches to semantic enrichment and storage of 3D models along with meta-data are just emerging. This paper presents challenges and trends to overcome the latter issues and demonstrates latest developments for annotation of 3D artifacts and their subsequent export to Europeana, the European digital library, for integrated, interactive 3D visualization within regular web browsers taking advantage of technologies such as WebGl and X3D.

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Kahn, Svenja; Fellner, Dieter W. (Betreuer); Stricker, Didier (Betreuer)

Precise Depth Image Based Real-Time 3D Difference Detection

2014

Darmstadt, TU, Diss., 2014

3D difference detection is the task to verify whether the 3D geometry of a real object exactly corresponds to a 3D model of this object. Detecting differences between a real object and a 3D model of this object is for example required for industrial tasks such as prototyping, manufacturing and assembly control. State of the art approaches for 3D difference detection have the drawback that the difference detection is restricted to a single viewpoint from a static 3D position and that the differences cannot be detected in real time. This thesis introduces real-time 3D difference detection with a hand-held depth camera. In contrast to previous works, with the proposed approach, geometric differences can be detected in real time and from arbitrary viewpoints. Therefore, the scan position of the 3D difference detection be changed on the fly, during the 3D scan. Thus, the user can move the scan position closer to the object to inspect details or to bypass occlusions. The main research questions addressed by this thesis are: Q1 How can 3D differences be detected in real time and from arbitrary viewpoints using a single depth camera? Q2 Extending the first question, how can 3D differences be detected with a high precision? Q3 Which accuracy can be achieved with concrete setups of the proposed concept for real time, depth image based 3D difference detection? This thesis answers Q1 by introducing a real-time approach for depth image based 3D difference detection. The real-time difference detection is based on an algorithm which maps the 3D measurements of a depth camera onto an arbitrary 3D model in real time by fusing computer vision (depth imaging and pose estimation) with a computer graphics based analysis-by-synthesis approach. Then, this thesis answers Q2 by providing solutions for enhancing the 3D difference detection accuracy, both by precise pose estimation and by reducing depth measurement noise. A precise variant of the 3D difference detection concept is proposed, which combines two main aspects. First, the precision of the depth camera's pose estimation is improved by coupling the depth camera with a very precise coordinate measuring machine. Second, measurement noise of the captured depth images is reduced and missing depth information is filled in by extending the 3D difference detection with 3D reconstruction. The accuracy of the proposed 3D difference detection is quantified by a ground-truth based, quantitative evaluation. This provides an answer to Q3. The accuracy is evaluated both for the basic setup and for the variants that focus on a high precision. The quantitative evaluation using real-world data covers both the accuracy which can be achieved with a time-of-flight camera (SwissRanger 4000) and with a structured light depth camera (Kinect). With the basic setup and the structured light depth camera, differences of 8 to 24 millimeters can be detected from one meter measurement distance. With the enhancements proposed for precise 3D difference detection, differences of 4 to 12 millimeters can be detected from one meter measurement distance using the same depth camera. By solving the challenges described by the three research question, this thesis provides a solution for precise real-time 3D difference detection based on depth images. With the approach proposed in this thesis, dense 3D differences can be detected in real time and from arbitrary viewpoints using a single depth camera. Furthermore, by coupling the depth camera with a coordinate measuring machine and by integrating 3D reconstruction in the 3D difference detection, 3D differences can be detected in real time and with a high precision.

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Caldera, Christian; Berndt, Rene; Eggeling, Eva; Schröttner, Martin; Fellner, Dieter W.

PRIMA - Towards an Automatic Review/Paper Matching Score Calculation

2014

Sehring, Hans-Werner (Ed.) et al.: CONTENT 2014 : The Sixth International Conference on Creative Content Technologies [online]. [cited 18 June 2015] Available from: http://www.thinkmind.org/index.php?view=instance&instance=CONTENT+2014: ThinkMind, 2014, pp. 71-75

International Conference on Creative Content Technologies (CONTENT) <6, 2014, Venice, Italy>

Programme chairs of scientific conferences face a tremendous time pressure. One of the most time-consuming steps during the conference workflow is assigning members of the international programme committee (IPC) to the received submissions. Finding the best-suited persons for reviewing strongly depends on how the paper matches the expertise of each IPC member. While various approaches like "bidding" or "topic matching" exist in order to make the knowledge of these expertises explicit, these approaches allocate a considerable amount of resources on the IPC member side. This paper introduces the Paper Rating and IPC Matching Tool (PRIMA), which reduces the workload for both - IPC members and chairs - to support and improve the assignment process.

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Baar, Teun; Samadzadegan, Sepideh; Brettel, Hans; Urban, Philipp; Segovia, Maria V. Ortiz

Printing Gloss Effects in a 2.5D System

2014

Segovia, Maria V. Ortiz (Ed.) et al.: Measuring, Modeling, and Reproducing Material Appearance. Bellingham: SPIE Press, 2014. (Proceedings of SPIE 9018), pp. 90180M-1 - 90180M-8

Measuring, Modeling, and Reproducing Material Appearance (MMRMA) <1, 2014, San Francisco, CA, USA>

An important aspect for print quality assessment is the perceived gloss level across the printout. There exists a strong relationship between the surface roughness of a printout and the amount of specular reflection which is perceived as gloss variations. Different print parameters influence the surface roughness of the printouts such as the paper substrate, the type of inks and the print method. The lack of control over the print's surface roughness may result in artifacts such as bronzing and differential gloss. Employing a 2.5D or relief printing system, we are able to control the printout roughness by manipulating the way the ink is deposited in a layer-by-layer basis. By changing the deposition time in between two layers of white ink and the order on which the pixels are printed, we achieve different gloss levels from a matte to a glossy appearance that can be controlled locally. Understanding the relationship between different printing parameters and the resulting gloss level allows us: to solve differential gloss artifacts (to obtain a print with a full gloss or matte finish) and to use the local gloss variations to create reflection effects in the printouts. Applications related to security printing have also been explored. Our results showed a reduced level of gloss toward a matte appearance as the ink deposition time between the layers was increased, allowing more time for the ink to dry between passes. We measured the gloss levels using a gloss meter and a psychophysical experiment was conducted to validate our measurements and observations.

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Butt, Moazzam; Damer, Naser; Rathgeb, Christian

Privacy Preserved Duplicate Check using Multi-biometric Fusion

2014

International Society of Information Fusion (ISIF): FUSION 2014 : 17th International Conference on Information Fusion. The Institute of Electrical and Electronics Engineers (IEEE), 2014, 7 p.

International Conference on Information Fusion (FUSION) <17, 2014, Salamanca, Spain>

Automated recognition of individuals can be performed using biometrics without any requirement of explicit knowledge of a PIN or a password. On the one side biometrics has given convenience to citizens as they do not need to memorize a bunch of passwords, but on the other side intra (inter) class variations within (between) biometric features makes biometric authentications untrustworthy. Therefore, decisions based on biometric authentications are made more reliable by using several biometric authentications performed on single or multiple biometric modalities (i.e. multi-biometric fusion). This paper describes a method to identify if a person tries to re-enrol him/herself in a database, when he/she is already enrolled. This is referred to as duplicate check. In this work, duplicate check is performed using two modalities: face and iris. The templates used during the duplicate check are compliant to the ISO/IEC 24745 - Biometric information protection. Such templates are known as protected biometric templates. The protected biometric templates used in this work are generated using the recently published irreversible transformation based on Bloom filters. Scores are calculated from face and iris Bloom filters based templates by comparison with their respective enrolment templates using the normalized Hamming distance. As a decision of the duplicate check, these scores from both modalities are fused with appropriate weighting factors in order to get improved performance compared to using single individual modalities. The presented scheme is experimentally validated using two public benchmark databases namely the LFW and the CASIA-Iris-Thousand databases for face and iris respectively.

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Privacy Protection of Biometric Templates

2014

Stephanidis, Constantine (Ed.): HCI International 2014 - Posters' Extended Abstracts. Proceedings Part I : HCI International 2014. Berlin, Heidelberg, New York: Springer, 2014. (Communications in Computer and Information Science (CCIS) 434), pp. 153-158

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

Although many biometric characteristics are not secrets, biometric reference data (also known as biometric templates) need to be stored securely and to be protected against unauthorized use. For this purpose, biometric template protection techniques have been developed that do not only prevent privacy leakage and provide confidentiality of the stored biometric templates, but address also problems like identity theft and cross-matching of biometric templates stored in different systems. This paper describes the security and privacy risks associated with storing biometric data and highlights the necessity of using biometric template protection as a potential remedy to these risks. Privacy considerations are discussed with respect to using fingerprint verification for access control to a public outdoor swimming pool.

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Zmugg, René; Thaller, Wolfgang; Krispel, Ulrich; Edelsbrunner, Johannes; Havemann, Sven; Fellner, Dieter W.

Procedural Architecture Using Deformation-aware Split Grammars

2014

The Visual Computer, Vol.30 (2014), 9, pp. 1009-1019. Published online: 29 December 2013

With the current state of video games growing in scale, manual content creation may no longer be feasible in the future. Split grammars are a promising technology for large-scale procedural generation of urban structures, which are very common in video games. Buildings with curved parts, however, can currently only be approximated by static pre-modelled assets, and rules apply only to planar surface parts. We present an extension to split grammar systems that allow the creation of curved architecture through integration of free-form deformations at any level in a grammar. Further split rules can then proceed in two different ways. They can either adapt to these deformations so that repetitions can adjust to more or less space, while maintaining length constraints, or they can split the deformed geometry with straight planes to introduce straight structures on deformed geometry.

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Havemann, Sven; Wagener, Olaf; Fellner, Dieter W.

Procedural Shape Modeling in Digital Humanities: Potentials and Issues

2014

Ioannides, Marinos (Ed.) et al.: 3D Research Challenges in Cultural Heritage : A Roadmap in Digital Heritage Preservation. Berlin, Heidelberg, New York: Springer, 2014. (Lecture Notes in Computer Science (LNCS) 8355), pp. 64-77

Procedural modeling is a technology that has great potential to make the abundant variety of shapes that have to be dealt with in Digital Humanities accessible and understandable. There is a gap, however, between technology on the one hand and the needs and requirements of the users in the Humanities community. In this paper we analyze the reasons for the limited uptake of procedural modeling and sketch possible ways to circumvent the problem. The key insight is that we have to find matching concepts in both fields, which are on the one hand grounded in the way shape is explained, e.g., in art history, but which can also be formalized to make them accessible to digital computers.

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Siegmund, Dirk; Busch, Christoph (Betreuer); Damer, Naser (Betreuer)

Prototypical Development of an In-Shop Advertisment System using Body Dimension Recognition

2014

Darmstadt, Hochschule, Master Thesis, 2014

This thesis outlines a system created to give consumers in the fashion industry an idea of how an item of clothing will look on them before trying it on. In the form of a short video, items of clothing are projected virtually onto an image of the user. Through the use of this system, retailers and manufacturers have the chance to immediately display their clothes on potential customers.

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Bieber, Gerald; Papenfuß, Frank; Vahl, Matthias; Woitzel, Egmont

Prototyping-Plattform zur Pose-Erfassung mobiler Geräte mit optischen und Inertialsensoren

2014

Bieber, Gerald (Ed.) et al.: WOAR 2014 : Proceedings of the Workshop on Sensor-based Activity Recognition. Stuttgart: Fraunhofer Verlag, 2014, pp. 39-50

Workshop on Sensor-Based Activity Recognition (WOAR) <1, 2014, Rostock, Germany>

In diesen Artikel wird eine Prototyping-Plattform zur Erfassung von Position und Orientierung mobiler Geräte mittels verschiedener Sensoren vorgestellt. Nach der Darstellung des Standes der Technik und der Anwendung in unterschiedlichen Bereichen wird die Plattform mit ihren Sensoren beschrieben. Anschließend werden die im Forschungsvorhaben eKon1 bereits entwickelten und geplanten Verfahren vorgestellt. Hierbei wird detailliert auf die Nutzung einer nach oben gerichteten, fischäugigen Kamera (Deckenkamera) eingegangen, um abschließend einen Ausblick auf die zu erwarteten Ergebnisse und Entwicklungen zu geben.

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Steger, Teena; Wesarg, Stefan

Quantitative Analysis of Marker Segmentation for C-Arm Pose Based Navigation

2014

Romero, Laura M. Roa (Ed.): XIII Mediterranean Conference on Medical and Biological Engineering and Computing : MEDICON 2013. Berlin, Heidelberg, New York: Springer, 2014. (IFMBE Proceedings 41), pp. 487-490

The Mediterranean Conference on Medical and Biological Engineering and Computing (MEDICON) <13, 2013, Seville, Spain>

Intraoperative C-arm fluoroscopy is used for better instrument guidance during bronchoscopy. Unfortunately, C-arm images do not provide depth information. But, offering 3D instrument localization would enable faster and more accurate guidance of the bronchoscope. Using the C-arm pose, this can be achieved by combining intraoperative fluoroscopy with a preoperative CT. Thus, the 3D position of the bronchoscope tip inside the bronchial tree can be located and visualized. We developed a marker plate for C-arm pose estimation, which is placed on the patient table. The markers are made of steel and appear in two different shapes: spheres and sticks. Detecting the markers is essential for the C-arm pose estimation method. In this work, we present and evaluate two detection methods for detecting the projected markers on the fluoroscopy images. Tests on cadaver images showed very good results regarding robustness and precision: For circles and lines, 80% and 85%, respectively, of all visible markers were detected, whereas only 1% and 3%, respectively, of all detected markers were missegmented.

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Flach, Guntram; Kubach, Michael; OÖzmü, Eray; Wehrenberg, Immo

Realisierung von vertrauenswürdigem Cloud-Computing mit SkIDentity: Der Anwendungsfall in Wertschöpfungsketten der Automobilindustrie

2014

Plödereder, Erhard (Ed.) et al.: 44. Jahrestagung der Gesellschaft für Informatik. INFORMATIK 2014 : Big Data - Komplexität meistern. Bonn: Köllen, 2014. (GI-Edition - Lecture Notes in Informatics (LNI) P-232), pp. 271-276

CloudCycle Workshop <2014, Stuttgart, Germany>

Ziel des SkIDentity-Projektes ist es, eine tragfähige Brücke zwischen den sicheren elektronischen Ausweisen (eID) und den heute existierenden bzw. sich entwickelnden Cloud-Computing-Infrastrukturen zu schlagen. Somit können vertrauenswürdige Identitäten für die Cloud bereitgestellt und komplette Prozess- und Wertschöpfungsketten sicher gestaltet werden. Hierfür werden existierende Komponenten, Dienste und Vertrauensinfrastrukturen zu einer umfassenden, rechtskonformen, wirtschaftlich sinnvollen und sicheren Identitätsinfrastruktur für die Cloud integriert und in breitenwirksamen Pilotprojekten erprobt. Eine solche Pilotapplikation ist ein Projektworkspace, der auf die Bedürfnisse der verteilten Wertschöpfungsketten der Automobilindustrie abgestimmt ist. Die SkIDentity-Technologie ermöglicht über einen eID-Broker den verschiedenen an einem Projekt beteiligten Entwicklern eine starke Authentisierung am Projektworkspace mit den unterschiedlichen bereits in ihrem Unternehmen vorhandenen Credentials im Sinne eines föderierten Identitätsmanagements. Diese Arbeit stellt die SkIDentity-Technologie vor und illustriert deren Vorteile anhand der Pilotapplikation.

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Rus, Silvia; Große-Puppendahl, Tobias; Kuijper, Arjan

Recognition of Bed Postures Using Mutual Capacitance Sensing

2014

Aarts, Emile (Ed.) et al.: Ambient Intelligence : European Conference, AmI 2014. Berlin, Heidelberg, New York: Springer, 2014. (Lecture Notes in Computer Science (LNCS) 8850), pp. 51-66

European Conference on Ambient Intelligence (AmI) <11, 2014, Eindhoven, The Netherlands>

In recent years, mutual capacitive sensing made significant advances in the field of gathering implicit contextual data. These systems find broad usage in pervasive activity-recognition systems, installed stationary or made portable. In the domain of context recognition new ways of interaction with the environment opened up since conductive objects can be detected under certain conditions at distances up to 50 cm. This paper investigates an approach to recognize bed postures using mutual capacitance sensing. The overall goal is to develop a technological concept that can be applied to recognize bed postures of patients in elderly homes. The use of this contextual data may lead to many desired benefits in elderly care e.g. the better prevention of decubitus ulcer, a condition caused by prolonged pressure on the skin resulting in injuries to skin and underlying tissues. For this, we propose a low-cost grid of crossed wires of 48 measurement points placed between the mattress and the bed sheet. The experimental results analyze a set of five lying positions. We achieved for all tested individuals an accuracy of 80.76% and for several individuals of the same bodysize an accuracy of 93.8%.

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Olbrich, Manuel; Franke, Tobias; Rojtberg, Pavel

Remote Visual Tracking for the (Mobile) Web

2014

Polys, Nicholas F. (General Chair) et al.: Proceedings Web3D 2014 : 19th International Conference on 3D Web Technology. New York: ACM, 2014, pp. 27-33

International Conference on 3D Web Technology (WEB3D) <19, 2014, Vancouver, BC, Canada>

Augmented Reality is maturing, but in a world where we are used to straightforward services on the internet, Augmented Reality applications require a lot of preparation before they can be used. Our approach shows how we can bring Augmented Reality into a normal web browser, or even browsers on mobile devices. We show how we are, with recent features of HTML5, able to augment reality based on complex 3D tracking in a browser without having to install or set up any software on a client. With this solution, we are able to extend 3D Web applications with AR and reach more users with a reduced usability barrier. A key contribution of our work is a pipeline for remote tracking built on web-standards.

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Brunton, Alan; Salazar, Augusto; Bolkart, Timo; Wuhrer, Stefanie

Review of Statistical Shape Spaces for 3D Data with Comparative Analysis for Human Faces

2014

Computer Vision and Image Understanding, Vol.128 (2014), pp. 1-17

With systems for acquiring 3D surface data being evermore commonplace, it has become important to reliably extract specific shapes from the acquired data. In the presence of noise and occlusions, this can be done through the use of statistical shape models, which are learned from databases of clean examples of the shape in question. In this paper, we review, analyze and compare different statistical models: from those that analyze the variation in geometry globally to those that analyze the variation in geometry locally. We first review how different types of models have been used in the literature, then proceed to define the models and analyze them theoretically, in terms of both their statistical and computational aspects. We then perform extensive experimental comparison on the task of model fitting, and give intuition about which type of model is better for a few applications. Due to the wide availability of databases of high-quality data, we use the human face as the specific shape we wish to extract from corrupted data.

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

Revisiting Perceptually Optimized Color Mapping for High-Dimensional Data Analysis

2014

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

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

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

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Prediger, Mark; Braun, Andreas; Marinc, Alexander; Kuijper, Arjan

Robot-Supported Pointing Interaction for Intelligent Environments

2014

Streitz, Norbert (Ed.) et al.: Distributed, Ambient, and Pervasive Interactions : DAPI 2014. Berlin, Heidelberg, New York: Springer, 2014. (Lecture Notes in Computer Science (LNCS) 8530), pp. 172-183

International Conference on Distributed, Ambient and Pervasive Interactions (DAPI) <2, 2014, Heraklion, Crete, Greece>

A natural interaction with appliances in smart environment is a highly desired form of controlling the surroundings using intuitively learned interpersonal means of communication. Hand and arm gestures, recognized by depth cameras, are a popular representative of this interaction paradigm. However they usually require stationary units that limit applicability in larger environments. To overcome this problem we are introducing a self-localizing mobile robot system that autonomously follows the user in the environment, in order to recognize performed gestures independent from the current user position. We have realized a prototypical implementation using a custom robot platform and evaluated the system with various users.

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Eicke, Tim Nicolas; Jung, Yvonne; Kuijper, Arjan

Robust Real-Time Shadows for Dynamic 3D Scenes on the Web

2014

Stephanidis, Constantine (Ed.): HCI International 2014 - Posters' Extended Abstracts. Proceedings Part I : HCI International 2014. Berlin, Heidelberg, New York: Springer, 2014. (Communications in Computer and Information Science (CCIS) 434), pp. 574-578

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

The authentic display of shadows by modern video games has long become a matter of course. On the web however, this is somewhat different: the rendering of three dimensional scenes in the browser has only in recent years been on the rise. At best, shadows have only played a minor part in that development, despite their importance regarding recognition of spacial relationships in human vision and general increase of a scene's authenticity. An important part in the development of web-based 3D is played by the open-source JavaScript framework X3DOM, as it provides an approach for the integration of declarative 3D in HTML5. However the framework too only offers rudimentary shadow rendering techniques that hardly meet today's demands. This work tackles this issue by first examining existing shadow mapping techniques for their suitability in the web context and based on that developing and implementing a concept for the enhancement of shadow display in X3DOM.

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Schinko, Christoph; Berndt, Rene; Eggeling, Eva; Fellner, Dieter W.

A Scalable Rendering Framework for Generative 3D Content

2014

Polys, Nicholas F. (General Chair) et al.: Proceedings Web3D 2014 : 19th International Conference on 3D Web Technology. New York: ACM, 2014, pp. 81-87

International Conference on 3D Web Technology (WEB3D) <19, 2014, Vancouver, BC, Canada>

Delivering high quality 3D content through a web browser is still a challenge especially when intellectual property (IP) protection is necessary. Thus, the transfer of 3D modeling information to a client should be avoided. In our work we present a solution to this problem by introducing a server-side rendering framework. Only images are transferred to the client, the actual 3D content is not delivered. By providing simple proxy geometry it is still possible to provide direct interaction on the client. Our framework incorporates the Generative Modeling Language (GML) for the description and rendering of generative content. It is then possible to not only interact with the 3D content, but to modify the actual shape within the possibilities of the generative content. By introducing a control layer and encapsulating processing and rendering of the generative content in a so called GML Rendering Unit (GRU) it is possible to provide a scalable rendering framework.