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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 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 Book Reviews(Blackwell Publishers Ltd and the Eurographics Association, 1998)Item Calendar of Events(Blackwell Publishers Ltd and the Eurographics Association, 1998)Item Color Fidelity in Computer Graphics: a Survey(Blackwell Publishers Ltd and the Eurographics Association, 1998) Rougeron, Gilles; Peroche, BernardThe purpose of this paper is to make a state of the art for color fidelity in computer graphics. Color fidelity includes three steps. The first one is the spectral rendering phase which attributes a spectrum to each pixel of a picture. During the second step, a spectral data is transformed into a set of tristimulus values in the XYZ color space. The purpose of the third step, called Color Reproduction Function, is to determine the RGB values displayable on the screen, in such a way that subjective fidelity is reached. We especially detail the two last steps of the color fidelity process; we also point out the work still remaining to be done in this field and we propose some research ways.Item Editorial(Blackwell Publishers Ltd and the Eurographics Association, 1998) Coquillart, Sabine; Seidel, Hans-PeterItem Entire Issue(Blackwell Publishers Ltd and the Eurographics Association, 1998)Item Eurographics '98(Blackwell Publishers Ltd and the Eurographics Association, 1998)Item Eurographics '98(Blackwell Publishers Ltd and the Eurographics Association, 1998)Item Join Now!(Blackwell Publishers Ltd and the Eurographics Association, 1998)Item A Modelling Method and User Interface for Creating Plants(Blackwell Publishers Ltd and the Eurographics Association, 1998) Lintermann, Bernd; Deussen, OliverWe present a modelling method and graphical user interface for the creation of natural branching structures such as plants. Structural and geometric information is encapsulated in objects that are combined to form a description of the model. The model is represented graphically as a structure graph and can be edited interactively. Global and partial constraint techniques are integrated on the basis of tropisms, free-form deformations and pruning operations to allow the modelling of specific shapes. We show examples to illustrate the design process and evaluate the user interface.Item Network Service(Blackwell Publishers Ltd and the Eurographics Association, 1998)Item The Priority Face Determination Tree for Hidden Surface Removal(Blackwell Publishers Ltd and the Eurographics Association, 1998) James, A.; Day, A. M.Many virtual environments are built from a set of polygons that form the basis of objects in the scene. Using priority-list algorithms, the sequence in which these polygons are drawn is dependent upon the location of an observer; the polygons must be ordered correctly before a realistic image can be displayed. It is necessary for a scene to be drawn correctly in real time from all locations before the observer can move interactively around the scene with complete freedom.The binary-space partitioning (BSP) tree developed by Fuchs, Kedem and Naylor in 1980 stores the view independent priority of a set of polygons which can be used to obtain the correct order for any given view-point. However, the number of polygons grows significantly due to the BSP splitting stage, increasing the number of nodes in the tree. This affects linearly the number of tests necessary to traverse the tree to obtain the priority of the set of polygons.The algorithm presented here is built using its associated BSP tree, but attempts to reduce the number of tests to, log4/3n, at the cost of a tree of size of O(N1.5log4/3n?1), where n is the initial number of polygons in the scene, and N the resulting number after BSP splitting. To achieve the increase in run-time efficiency, a height plane is used to restrict the view point of the observer to a fixed height, but the key to the efficiency of the algorithm is in the use of polygonal dependencies. In the scene; if we know our location relative to the front or back of a polygon, then our position relative to one-quarter of the remaining polygons, in the expected worst-case, can be determined.Item Siggraph/Eurographics Workshop on Graphics Hardware(Blackwell Publishers Ltd and the Eurographics Association, 1998) Schneider, Bengt-Olaf