EG1998
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Item Advanced Application of Volume Visualization Methods in Medicine(Eurographics Association, 1998) Sakas, G.; Pommert, A.Tomographic medical imaging techniques have become more popular in recent years. The wide availability of CT, MRI and Ultrasound in most large hospitals results in a rapidly increasing number of examinations with these devices. The State of The Art Report summarises the application of techniques developed over the recent years for visualising volumetric medical data common in modern medical imaging modalities such as CT, MRA, MRI, Nuclear Medicine, 3D-Ultrasound, Laser Confocal Microscopy etc. Although all of the modalities listed above provide "slices of the body", significant differences exist between the image content of each modality. The focus of the Report is be less in explaining algorithms and rendering techniques, but rather to point out their applicability, benefits, and potential in the medical environment. In the first part, methods for all steps of the volume visualization pipeline from data preprocessing to object display are reviewed, with special emphasis on data structures, segmentation, and surface- and volume-based rendering. Furthermore, multimodality matching, intervention rehearsal, and aspects of image quality are discussed. In the second part applications are illustrated from the areas of craniofacial surgery, traumatology, neurosurgery, radiotherapy, and medical education. Furtherly, some new applications of volumetric methods are presented: 3D ultrasound, laser confocal datasets, and 3D-reconstruction of cardiological datasets, i.e. vessels as well as ventricles. These new volumetric methods are currently under development but due to their enormeous application potential they are expected to be clinically accepted within the next years.Item Agents in multi-user virtual environments(Eurographics Association, 1998) Paul, Christian; Peters, Ralph; Graeff, AndreasIn this paper,we introduce the use of agents in combinationwith virtual realities as one possibility to enhancefuture communication systems.These agents support the user and his/her interactionwith objects within the virtual world. Themain goal of our approachincludes the implementation of helpers, personalassistants, and tour guides tomake multi-user virtual environmentsmore lively and realistic.Item Behavior Authoring for VRML Applications in Industry(Eurographics Association, 1998) Dörner, R.; Elcacho, C.; Luckas, V.As VRML offers behavior definition on different levels (animation behavior, interaction behavior, hypermedia behavior, application behavior) an authoring tool for VRML content creation has to comprise a dedicated behavior editor. An editor for this purpose has been conceived based upon object-oriented concepts. The concept stresses reusability and support for non-expert users. Reusable elements with object-specific behavior are used Clipart-like to author the scene easily. The editor itself offers a library of generally applicable behaviors, too. This enables the author to use a wide range of pre-defined behavior. The editor keeps track of the authors’ actions and out of this information a VRML file is created automatically. A first implementation of this editor focuses on special elements and behaviors needed in industrial applications.Item Comparison between two Three-Dimensional Edge Operators applied in a 3D Navigation Approach(Eurographics Association, 1998) Dillenseger, J.L.; Sousa Santos, B.This paper will compare two 3D surface detection and normal estimation operators applied on a rough voxel database. These approaches can be applied as virtual endoscopy for the exploriation of 3D medical image volumes. The data context will be first explained, the two methodologies will be then described and evaluated on a 3D model data. Keywords - Surface detector, normal estimator, 3D moment operator, virtual endoscopy.Item Distributed Cooperative Visualization(Eurographics Association, 1998) Brodlie, K.W.; Duce, D.A.; Gallop, J.R.; Wood, J.D.Visualization is essentially a collaborative activity, widely used in many scientific and engineering disciplines. Visualization may be used to convey insight into phenomena that are well-understood, or to present new data with a view to finding new patterns of meaning and new phenomena. Visualization is a powerful tool in presentations (lectures, seminars, papers etc) and in discussions between colleagues. We are seeing a growth in the use of video conferencing to facilitate meetings between participants in geographically separate locations, both specialized facilities (video conference rooms) using dedicated communications channels (ISDN, ATM etc) and desktop video conferencing using the Internet and multicast (Mbone) communications. Distributed cooperative visualization aims to enhance the video conferencing environment (usually the desktop environment) with access to visualization facilities. At the most basic level, pre-generated visualizations may be shared through a shared whiteboard tool. Richer approaches enable users to share control of the kind of visualization generated and the parameters used in the generation. The World Wide Web provides a basis for asynchronous cooperative working and there are experimental extensions in the direction of cooperative browsing. VRML provides the basis for sharing 3D graphics over the Internet.We look at ways in which VRML is being used in visualization, to generate models which may be browsed by participants in a session. Asynchronous collaboration becomes possible by recording the details of the visualization created by one participant, and making this available to subsequent ‘visitors’ to the Web site. A multiuser audit trail emerges. Developments on multi-user VRML worlds also have potential applications in visualization, providing a form of synchronous collaboration. This STAR reviews the state of the art in these areas, draws out common threads in these diverse approaches and looks at strengths, weaknesses and opportunities for further development in this field.Item Dynamic Load Balancing in Distributed Virtual Environment(Eurographics Association, 1998) Mantler, S.; Schmalstieg, D.-Item Face-to-Face Communication System in Cyberspace by Voice Driven Avatar(Eurographics Association, 1998) Morishima, S.; Yotsukure, T.; Fuji, E.Recently computer can make cyberspace to walk through by an interactive virtual reality technique. An avatar in cyberspace can bring us a virtual face-to-face communication environment. In this paper, we realize an avatar which has a real face in cyberspace and construct a multi-user communication system by voice transmission through network. Voice from microphone is analyzed and transmitted, then mouth shape and facial expression of avatar are synchronously estimated and synthesized on real time.Item A Faster Algorithm for 3D Discrete Lines(Eurographics Association, 1998) Boyer, V.; Bourdin, J. J.-Item The Hidden Face Determination Tree(Eurographics Association, 1998) James, A.; Day, A.M.Hidden surface removal can be achieved using the Priority Face Determination (PFD) tree to create a priority ordering of n polygons in log4=3 n time. In this paper, we describe the Hidden Face Determi- nation (HFD) tree which is based upon the PFD tree. The HFD tree is constructed in a similar way as the PFD tree, but an addition means that polygons completely hidden by others in the scene can be determined at each node. Thus, not only does the HFD tree calculate the priority order of polygons in log4=3 n time, but determines which polygons are invisible from a given location.Item Immersive High Quality Communication(Eurographics Association, 1998) Gräff, A.; Schiffner, N.This shows our vision of advanced high quality tele-communication which can be achieved by combining large-scale displays, real-time audio/video transmission, virtual reality and global, high bandwidth computer networks.Item Interactive Analysis for MPEG-4 Facial Models Configuration(Eurographics Association, 1998) Antunes Abrantes, G.; Pereira, F.-Item Interpolation and Approximation of Surfaces from Three-Dimensional Scattered Data Points(Eurographics Association, 1998) Mencl, R.; Möller, H.There is a wide range of applications for which surface interpolation or approximation from scattered data points in space is important. Dependent on the field of application and the related properties of the data, many algorithms were developed in the past. This contribution gives a survey of existing algorithms, and identifies basic methods common to independently developed solutions. We distinguish surface construction based on spatial subdivision, distance functions, warping, and incremental surface growing. The systematic analysis of existing approaches leads to several interesting open questions for further research.Item Introduction to Programming with Java 3D(Eurographics Association, 1998) Nadeau, D. R.; Sowizral, H. A.Java 3D is a new cross-platform API for developing 3D graphics applications in Java. Java 3D’s feature set has been designed to enable quick development of complex 3D applications, and at the same time enable fast and efficient implementations on a variety of platforms, from PCs to workstations. Using Java 3D, software developers can build cross-platform applications that build 3D scenes programmatically, or via loading 3D content from VRML, OBJ, and/or other external files. The Java 3D API includes a rich feature set for building shapes, composing behaviors, interacting with the user, and controlling rendering details. Participants in this tutorial will learn the concepts behind Java 3D, the Java 3D class hierarchy, typical usage patterns, ways of avoiding common mistakes, animation and scene design techniques, and tricks for increasing performance and realism.Item Introduction to VRML 97(Eurographics Association, 1998) Nadeau, D. R.VRML (the Virtual Reality Modeling Language) is an international standard for describing 3-D shapes and scenery on the World Wide Web. VRML’s technology has very broad applicability, including web-based entertainment, distributed visualization, 3-D user interfaces to remote web resources, 3-D collaborative environments, interactive simulations for education, virtual museums, virtual retail spaces, and more. VRML is a key technology shaping the future of the web. Participants in this tutorial will learn how to use VRML 97 (a.k.a. ISO VRML, VRML 2.0, and Moving Worlds) to author their own 3-D virtual worlds on the World Wide Web. Participants will learn VRML concepts and terminology, and be introduced to VRML’s text format syntax. Participants also will learn tips and techniques for increasing performance and realism. The tutorial includes numerous VRML examples and information on where to find out more about VRML features and use.Item Modelling Cloth Buckling and Drape(Eurographics Association, 1998) Dias, J.M.S.; Gamito, M.N.; Rebordao, J.M.We present a new computational model for plain woven fabrics. The model is able to represent known elastic behaviour in deformation, such as planar extension and shearing and out-of-plane bending, drape and buckling. The buckling behaviour is present both in shear and compression. Visual results of these deformation conditions are shown. The cloth is assumed to be an orthotropic linear elastic continuum, discretized by a mesh of triangles. For the planar deformation, we assume the hypothesis of the plate under plane stress, of the classical theory of Elasticity and each triangle corresponds to a Strain-Rosette. For the out-of plane deformation, we allow linear elasticity and non-linear displacement in bending, as expressed by the Bernoulli-Euler equation. Dynamic equilibrium is formulated using Newton’s 2nd law. We model non-linear elastic material behaviour, by piecewise linear approximation of measured data.Item Motion Reparametrization(Eurographics Association, 1998) da Silva, F.W.; Velho, L.; Gomes, J.This paper presents an algorithm for reparametrization of 1D signals in the discrete domain, according to a userdefined velocity function. The application outlined in this work is the reparametrization of joint curves obtained from human motion captured data. Using the method described here we were able to create effects such as slowmotion and accelerated-time.Item Multidimensional free-form deformation tools(Eurographics Association, 1998) Bechmann, D.A survey of free-form deformation tools where the deformation is controlled by manipulating a 0-D to 3-D tool. Characteristics of a model that includes all these and generalises the concept will be presented.Item Navigation through Virtual 3D Worlds for Facilitating Childrens Spatial Orientation(Eurographics Association, 1998) Volbracht, S.; Domik, G.Spatial orientation is an important ability which should be encouraged in geometry courses of elementary schools. A preferred approach (in Germany) typically involves navigation and wayfinding tasks with pictures of a town depicted in a book. The use of computer-generated, virtual 3D worlds for teaching spatial orientation raises (especially for computer scientists) the two following questions: 1. How effective are particular navigation techniques, aids, and motion controls for facilitating children's spatial orientation and therefore the navigation in virtual worlds? and 2. What trade-off between realistic features and computer performance is optimal? A virtual 3D-city, developed in an interdisciplinary project, acts as a testing environment to answer these questions. Preliminary results indicate differences between navigation techniques of children vs. adults. The results will also be important to designers of virtual 3D worlds as educational software in general, who need such information for improving children's navigation in 3D space.Item Overview of Parallel Photo-realistic Graphics(Eurographics Association, 1998) Reinhard, E.; Chalmers, A.G.; Jansen, F.W.Global illumination is an area of research which tries to develop algorithms and methods to render images of artificial models or worlds as realistically as possible. Such algorithms are known for their unpredictable data accesses and their high computational complexity. Rendering a single high quality image may take several hours, or even days. For this reason parallel processing must be considered as a viable option to compute images in a reasonable time. The nature of data access patterns and often the sheer size of the scene to be rendered, means that a straightforward parallelisation, if one exists, may not always lead to good performance. This holds for all three rendering techniques considered in this report: ray tracing, radiosity and particle tracing.Item