EG1998
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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 A Standard for Multimedia Middleware(Eurographics Association, 1998) Duke, D.J.; Herman, I.Hardware, software, and coding standards for digital media have played a significant role in making multimedia presentation an intrinsic compponent of many systems. However, these standards are primarily concerned with the storage, encoding and transport of media content, and have not been intended to address the integration of multimedia data into more general programming environments for media presentation. PREMO (PResentation Environments for Multimedia Objects) is a project within the SC24 committee of the International Organisation for Standardization (ISO) aimed at developing an API (Application Programmer Interface) that integrates the processing and presentation of distributed multimedia with that of synthesised graphics. This report summarises the contents of the PREMO standard and explains how the integration of graphics into a general framework for media processing is achieved.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 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 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 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 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 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 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 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 Using constraints to describe high-level behaviours in virtual worlds(Eurographics Association, 1998) Richard, N.; Codognet, P.; Grumbach, A.Our aim is to make the authoring of virtual worlds easier for non-specialists, in particular when programming pseudo-intelligent agents within virtual environments.We are designing a high-level language as well as a library of reusable building blocks. We are now working on the definition and the implementation of an homogeneous model for describing 3D objects, their attributes and their behaviours. Constraints are a simple declarative way to describe strong logical relationships between objects; those constraints must be satisfied as much as possible, in order to keep a system in a coherent state. When considering virtual worlds creation, we need to distinguish several kinds of relationships an author may want to express, especially constraints between agents living in an everchanging environment.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 A Semi-empirical Model for the Representation of Materials in Photorealistic Rendering(Eurographics Association, 1998) Hansmann, W.; Warncke, H.From the beginning of Computer Graphics various models intended to describe the optical properties of different materials have been proposed. Some of these models are purely empirical [1]. Others are very close to physics but they have a large computational overhead [2,3]. In this paper we introduce a new model for the representation of different materials in photorealistic rendering which is based on the microfacet approach and tailored to ray tracing. The proposed ideas are based on an equation developed by Hall and Greenberg [4]. The proposed model fills the gap between existing very primitive and highly sophisticated models, and because it is fast to compute and easy to understand it is not only interesting for scientists but also for practical purposes in industry. At the end of this paper several step by step improvements are described which will be integrated in the proposed equation in the near futureItem 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 Virtual Sewing System for Apparel Design(Eurographics Association, 1998) Soo Suh, Y.; Endou, Y.; Gotoh, D.; Kiyota, A.; Okabe, H.; Niwaya, H.; Shigeru, I.An apparel CAD system capable of 3D simulation of clothes is reported. The system works on personal computers, has graphical user interface and requires minimal input to indicate how to sew and put on the dress. The system automatically generates triangular mesh and calculates the mechanically stable state (i.e. no dynamics) of the dress put on the designated body. Pattern of the cloth can be mapped on the 3D shape and the distribution of stress can be also displayed. Fast simulation is achieved by our original method for function minimization.Item Item Interactive Analysis for MPEG-4 Facial Models Configuration(Eurographics Association, 1998) Antunes Abrantes, G.; Pereira, F.-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 Scanning and Reconstruction of human body parts(Eurographics Association, 1998) Borghese, N.A.; Ferrari, S.The reconstruction of 3D models of human body parts from range data is different with respect to that of general objects as they do not exhibit sharp discontinuities. Following this consideration, HRBF models which implement locally adapted filters are here introduced. They are based on stacking grids of Gaussians one over the other, where each grid operates at a different scale. The grids are not filled with Gaussians but these are inserted only in those crossings where the residual error is greater than the digitising noise. This allows to achieve a uniform reconstruction error. It results a very efficient and fast tool which can operate in real-time. Results on scanning a woman face are reported and discussed.