EG1998
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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 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.Item State of the Art in Perceptually Driven Radiosity(Eurographics Association, 1998) Prikryl, J.; Purgathofer, W.Despite its popularity among researchers the radiosity method still suffers of some disadvantages over other global illumination methods. Besides the fact that the original method allows only for solving the global illumination of environments consisting of purely diffuse surfaces, the method is rather computationally demanding. In the search for possible speed-up techniques one of the possibilities is to take also the characteristic features of the human visual system. Being aware of how the human visual perception works, one may compute the radiosity solution to lower accuracy in terms of physically based error metrics, but being sure that the physically correct solution won’t bring any improvements in the image for the human observer. In the following report we briefly summarize achievements in the radiosity research in the past years and present the state of the art in perceptual approaches used in computer graphics nowadays. We will give an overview of known tone-mapping and perceptually-based image comparison techniques that can be used in the scope of the radiosity method to further speed up the computational process. In the second part of the report we concentrate on known radiosity methods that already use these perceptual approaches to predict different visible errors of the result of the radiosity computation. We will not speak about importance-driven radiosity solutions, as those methods are based on using geometric visibility rather than on using human perception-aware techniques.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 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 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 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 Rendering and Visualization in Affordable Parallel Environments(Eurographics Association, 1998) Bartz, Dirk; Silva, Claudio; Schneider, Bengt-OlafThe scope of this full-day tutorial is the use of low and medium-cost parallel environments (less than US $ 60K) for high-speed rendering and visualization. In particular, our focus is on the parallel graphics programming of multi-processor PCs or workstations, and networks of both. The current technology push in the consumer market for graphics hardware, small multiprocessor machines, and fast networks is bound to make all of these components less expensive. In this tutorial, attendees will learn how to leverage these advances in consumer hardware to achieve faster rendering by using parallel rendering algorithms, and off-the-shelf software systems. This course will briefly touch the necessary tools to make basic use of this technology: parallel programming paradigms (shared memory, message passing) and parallel rendering algorithms (including image-, object-, and time- space parallelism). Advantages and issues of the different methods will be discussed on several examples of polygonal graphics and volume rendering.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 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 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 Subdivision Scheme for Smooth Interpolation of Quad-Mesh Data(Eurographics Association, 1998) Kobbelt, L. P.A simple interpolatory subdivision scheme for quadrilateral nets with arbitrary topology is presented which generates C1 surfaces in the limit. The scheme satisfies important requirements for practical applications in computer graphics and engineering. These requirements include the necessity to generate smooth surfaces with local creases and cusps. The scheme can be applied to open nets in which case it generates boundary curves that allow a C0- join of several subdivision patches. Due to the local support of the scheme, adaptive refinement strategies can be applied. We present a simple device to preserve the consistency of such adaptively refined nets.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 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 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 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 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 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.