Volume 17 (1998)
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Item 1998 Annual Index(Blackwell Publishers Ltd and the Eurographics Association, 1998)Item 2nd Eurographics Workshop on Parallel Graphics & Visualization - Call for Contributions(Blackwell Publishers Ltd and the Eurographics Association, 1998)Item 5th Eurographics Workshop on Design, Specification and Verification of Interactive Systems, DSV-IS '98(Blackwell Publishers Ltd, 1998)Item 8th Eurographics Workshop on Computer Animation and Simulation(Blackwell Publishers Ltd and the Eurographics Association, 1998) Thalmann, Daniel; Van De Panne, MichielItem 8th Eurographics Workshop on Rendering(Blackwell Publishers Ltd and the Eurographics Association, 1998) Dorsey, Julie; Slusallek, PhilippItem 9th Eurographics Workshop on Rendering(Blackwell Publishers Ltd and the Eurographics Association, 1998)Item 9th Eurographics Workshop on Visualization in Scientific Computing(Blackwell Publishers Ltd and the Eurographics Association, 1998)Item Accelerated Walkthroughs of Virtual Environments Based on Visibility Preprocessing and Simplification(Blackwell Publishers Ltd and the Eurographics Association, 1998) Wang, Yigang; Bao, Hujun; Peng, QunshengThis paper proposes a new preprocessing method for interactive rendering of complex polygonal virtual environments. The approach divides the space that observer can reach into many rectangular viewpoint regions. For each region, an outer rectangular volume (ORV) is established to surround it. By adaptively partitioning the boundary of the ORV together with the viewpoint region, all the rays that originate from the viewpoint region are divided into the beams whose potentially visible polygon number is less than a preset threshold. If a resultant beam is the smallest and intersects many potentially visible polygons, the beam is simplified as a fixed number of rays and the averaged color of the hit polygons is recorded. For other beams, their potentially visible sets (PVS) of polygons are stored respectively. During an interactive walkthrough, the visual information related to the current viewpoint is retrieved from the storage. The view volume clipping, visibility culling and detail simplification are efficiently supported by these stored data. The rendering time is independent of the scene complexity.Item Adaptive Supersampling in Object Space Using Pyramidal Rays(Blackwell Publishers Ltd and the Eurographics Association, 1998) Genetti, Jon; Gordon, Dan; Williams, GlenWe introduce a new approach to three important problems in ray tracing: antialiasing, distributed light sources, and fuzzy reflections of lights and other surfaces. For antialiasing, our approach combines the quality of supersampling with the advantages of adaptive supersampling. In adaptive supersampling, the decision to partition a ray is taken in image-space, which means that small or thin objects may be missed entirely. This is particularly problematic in animation, where the intensity of such objects may appear to vary. Our approach is based on considering pyramidal rays (pyrays) formed by the viewpoint and the pixel. We test the proximity of a pyray to the boundary of an object, and if it is close (or marginal), the pyray splits into 4 sub-pyrays; this continues recursively with each marginal sub-pyray until the estimated change in pixel intensity is sufficiently small.The same idea also solves the problem of soft shadows from distributed light sources, which can be calculated to any required precision. Our approach also enables a method of defocusing reflected pyrays, thereby producing realistic fuzzy reflections of light sources and other objects. An interesting byproduct of our method is a substantial speedup over regular supersampling even when all pixels are supersampled. Our algorithm was implemented on polygonal and circular objects, and produced images comparable in quality to stochastic sampling, but with greatly reduced run times.Item An Algorithm for Dynamic Color Management(Blackwell Publishers Ltd and the Eurographics Association, 1998) Fischer, MartinThough the problem of color quantization in static images is not completely solved, there are a few algorithms that produce good results. Color quantization with dynamic color requests is an unsolved problem. In this paper we present an algorithm that manages dynamic color allocations without advance knowledge of the sequence of color requests. It uses a dynamic color table that can be used simultaneously in multiple windows from one or more applications. Advance knowledge about color requirements will improve the results of the algorithm.Item All Articles(Blackwell Publishers Ltd and the Eurographics Association, 1998) -Item Animation of Biological Organ Growth Based on L-systems(Blackwell Publishers Ltd and the Eurographics Association, 1998) Durikovic, Roman; Kaneda, Kazufumi; Yamashita, HideoIn contrast with the growth of plants and trees, human organs can undergo significant changes in shape through a variety of global transformations during the growth period, such as bending or twisting. In our approach, the topology of a human organ is represented by a skeleton in the form of a tree or cycled graph. The length of skeleton growth can be simulated by an algebraic L-system that also produces discrete events. The paper shows how to include global transformations into the formalism of L-systems to obtain a continuous process. The shape of the organ is approximated by a number of ellipsoidal clusters centred at points on the skeleton. The proposed growth model of the organ continually responds to the positional changes of surrounding organs, thereby changing the organ shape locally. In our study, the stomach of a human embryo is used for the demonstration of organ development, and the methodology employed is also applicable to the animation of animal organs and their development.Item Anisotropic Solid Texture Synthesis Using Orthogonal 2D Views(Blackwell Publishers Ltd and the Eurographics Association, 1998) Dischler, J.M.; Ghazanfarpour, D.; Freydier, R.Analytical approaches, based on digitised 2D texture models, for an automatic solid (3D) texture synthesis have been recently introduced to Computer Graphics. However, these approaches cannot provide satisfactory solutions in the usual case of natural anisotropic textures (wood grain for example). Indeed, solid texture synthesis requires particular care, and sometimes external knowledge to "guess" the internal structure of solid textures because only 2D texture models are used for analysis. By making some basic assumptions about the internal structure of solid textures, we propose a very efficient method based on a hybrid analysis (spectral and histogram) for an automatic synthesis of solid textures. This new method allows us to obtain high precision solid textures (closely resembling initial models) in a large number of cases, including the difficult case of anisotropic textures.Item Anno 2010 - Remembering Our Future: Challenges and Frontiers of Human-Media Technology as the Kernel for Human-Centered Computing(Blackwell Publishers Ltd and the Eurographics Association, 1998) Encarnacao, JoseBased on a forecast by Battelle, Human-Media Technology is one of "technologyâ s top 10 challenges and opportunities" for the year 2010. The subject hereby is: "Humans live, science finds out how technology conforms". The goal is to develop environments that allow users to cooperate in the most efficient and natural way. Human-centered systems will have to incorporate people as an explicit design component. This lecture will address the main goals in developing such systems based on their general characteristics and the corresponding enabling technologies: Visualization (seeing the unseen), Virtual and Augmented Reality (environment must be immersive), and also Multimedia (to introduce the combination of visual, auditory and voice data). Examples from applications and case studies will support the clarification of ideas and goals. Several videos will be used to show the impact.So far, the human-centered interfaces to accommodate human perception and human response capabilities and limitations will have been presented and discussed. These interfaces allow to integrate the desired amount of immersion and cooperation (CSCW). Based on this, some "hands-on" life demos will be shown to discuss the state of the art of these technologies, like Virtual Tables (responsive workbenches), special I/O technologies, etc. Some of these demos will be stand-alone demos; others will show the potential of telecommunication for collaboration by connecting the floor with other locations to demonstrate CSCW-based visual tele-applications.Item Announcements(Blackwell Publishers Ltd and the Eurographics Association, 1998)Item Announcements(Blackwell Publishers Ltd and the Eurographics Association, 1998)Join Now! Network ServiceItem Author Index(Blackwell Publishers Ltd and the Eurographics Association, 1998)Item A Bernstein-Bezier Based Approach to Soft Tissue Simulation(Blackwell Publishers Ltd and the Eurographics Association, 1998) Roth, S.H.; Gross, Markus H.; Turello, Silvio; Carls, Friedrich R.This paper discusses a Finite Element approach for volumetric soft tissue modeling in the context of facial surgery simulation. We elaborate on the underlying physics and address some computational aspects of the finite element discretization.In contrast to existing approaches speed is not our first concern, but we strive for the highest possible accuracy of simulation. We therefore propose an extension of linear elasticity towards incompressibility and nonlinear material behavior, in order to describe the complex properties of human soft tissue more accurately. Furthermore, we incorporate higher order interpolation functions using a Bernstein-Bezier formulation, which has various advantageous properties, such as its integral polynomial form of arbitrary degree, efficient subdivision schemes, and suitability for geometric modeling and rendering. In addition, the use of tetrahedral Finite Elements does not put any restriction on the geometry of the simulated volumes.Experimental results obtained from a synthetic block of soft tissue and from the Visible Human Data Set illustrate the performance of the envisioned model.Item Book Reviews(Blackwell Publishers Ltd and the Eurographics Association, 1998)Books reviewed:Donnelly, Daniel. Web Design: The Next GenerationHege, H.-C. and Polthier, K. (editors). Visualization and MathematicsGibson, J. D., Berger, T., Lookabaugh, T., Lindbergh, D. andBaker, R. L. Digital Compression for MultimediaMorgan, Don. Numerical Methods For DSP Systems in CWainer, Howard. Visual Revelations: Graphical Tales of Fate and Deception from Napoleon Bonaparte to Ross PerotMaestri, George. Digital Character AnimationKlimek, Grazyna and Klimek, Maciej. Discovering Curves and Surfaces with MapleTrappl, Robert and Petta, Paolo (editors). Creating Personalities for Synthetic ActorsLohmann, Gabriele. Volumetric Image AnalysisMeinhardt, Hans. The Algorithmic Beauty of Sea Shells (2nd Edition)Palanque, Philippe and Paterno, Fabio (editors) Formal Methods in Human-Computer InteractionDai, Fan (editor). Virtual Reality for Industrial ApplicationsItem Book Reviews(Blackwell Publishers Ltd and the Eurographics Association, 1998)