Volume 16 (1997)
Permanent URI for this community
Browse
Browsing Volume 16 (1997) by Title
Now showing 1 - 20 of 101
Results Per Page
Sort Options
Item 1998 Cover Competition(Blackwell Publishers Ltd and the Eurographics Association, 1997)Item 5th EG Workshop on DSV-IS: call for participation(Blackwell Publishers Ltd and the Eurographics Association, 1997)Item 9th EG Workshop on Rendering: call for participation(Blackwell Publishers Ltd and the Eurographics Association, 1997)Item An Algorithmic Reflectance and Transmittance Model for Plant Tissue(Blackwell Publishers Ltd and the Eurographics Association, 1997) Baranoski, Gladimir V.G.; Rokne, Jon G.Recent developments in rendering have provided very realistic images. However, these images rarely show organic objects. We believe that one of the main difficulties of rendering these objects realistically is the lack of reflectance and transmittance models oriented to organic materials. In this paper an algorithmic reflectance and transmittance model for plant tissue oriented to computer graphics applications is presented. The model accounts for the three components of light propagation in plant tissues, namely surface reflectance, subsurface reflectance and transmittance, and mechanisms of light absorption by pigments present in these tissues. The model design is based on the available biological information, and it is controlled by a small number of biologically meaningful parameters. Its formulation, based on standard Monte Carlo techniques, guarantees its easy incorporation into most rendering systems. The spectral curves of reflectance and transmittance computed by the model are compared with measured curves from actual experiments.Item An Analysis of Quasi-Monte Carlo Integration Applied to the Transillumination Radiosity Method(Blackwell Publishers Ltd and the Eurographics Association, 1997) Szirmay-Kalos, Laszlo; Foris, Tibor; Neumann, Laszlo; Csebfalvi, BalazsThis paper presents an enhanced transillumination radiosity method that can provide accurate solutions at relatively low computational cost. The proposed algorithm breaks down the double integral of the gathered power to an area integral that is computed analytically and to a directional integral that is evaluated by quasi-Monte Carlo techniques. Since the analytical integration results in a continuous function of finite variation, the quasi-Monte Carlo integration that follows the analytical integration will be efficient and its error can be bounded by the Koksma-Hlawka inequality. The paper also analyses the requirements of the convergence, presents theoretical error bounds and proposes error reduction techniques. The theoretical bounds are compared with simulation results.Item Animation by Deformation of Space-Time Objects(Blackwell Publishers Ltd and the Eurographics Association, 1997) Aubert, Fabrice; Bechmann, DominiqueThis article presents the properties of animation with space-time objects. A space-time object means here a geometrical object embedded in R4 with a volumic topology. Resulting animations are obtained by deforming space-time objects with a free-form deformation model. In this way topological modifications, such as disconnecting or hole making, as well as classical geometrical modifications, can be created in an animated object.Item Applying Rounding-Up Integral Linear Interpolation to the Scan-Conversion of Filled Polygons(Blackwell Publishers Ltd and the Eurographics Association, 1997) Yao, Chengfu; Rokne, Jon G.This paper is motivated by a special linear interpolation problem encountered in scan-line algorithms for scan-conversion of filled polygons. rounding-up integral linear interpolation is defined and its efficient computation is discussed. The paper then incorporates rounding-up integral linear interpolation into a scan-line algorithm for filled polygons, and it discusses the implementation of the algorithm. This approach has the advantage of only requiring integer arithmetic in the calculations. Furthermore, the approach provides a unified treatment for calculating span extrema for left and right edges of the polygon that guarantees the mutual exclusiveness of the ownership of boundary pixels of two filled polygons sharing an edge.Item Auditor's Report(Blackwell Publishers Ltd and the Eurographics Association, 1997)Item Automatic Hierarchical Level of Detail Optimization in Computer Animation(Blackwell Publishers Ltd and the Eurographics Association, 1997) Mason, Ashton E.W.; Blake, Edwin H.We show that the hierarchical level of detail optimization problem is equivalent to a constrained version of the Multiple Choice Knapsack Problem, and present a new algorithm whose solution to it is at least half as good as the optimal one. The advantage of the hierarchical algorithm is that it allows the use of hierarchical level of detail descriptions in which shared representations may be provided for groups of objects. Rendering cost may then be saved to afford better renderings of more important objects, and the algorithm is capable of providing a complete representation of the visible scene even when the visible scene complexity is very high. Our algorithm has a worst case time complexity of O(nlogn), and is incremental so that it typically completes in only a few iterations. We introduce the use of perceptual evaluation to demonstrate the effectiveness of the use of representations for groups of objects that our algorithm allows.Item Book Reviews(Blackwell Publishers Ltd and the Eurographics Association, 1997) Howard, TobyItem Book Reviews(Blackwell Publishers Ltd and the Eurographics Association, 1997)Item Book Reviews(Blackwell Publishers Ltd and the Eurographics Association, 1997)Steinmetz, Ralf and Nahrstedt, Klara. Multimedia: Computing, Communications and ApplicationsStollnitz, Eric J, Derose, Tony D and Salesin, David H. Wavelets for Computer GraphicsPrusinkiewicz, P and Lindenmayer, A. The Algorithmic Beauty of PlantsGeary, David M and McClellan, Alan L. Graphic Java: Mastering the AWTSantos, Adelino. Multimedia and Groupware for EditingMagnenat Thalmann, Nadia and Thalmann, Daniel. Interactive Computer AnimationItem Book Reviews(Blackwell Publishers Ltd and the Eurographics Association, 1997)Item Bounded Radiosity - Illumination on General Surfaces and Clusters(Blackwell Publishers Ltd and the Eurographics Association, 1997) Stamminger, Marc; Slusallek, Philipp; Seidel, Hans-PeterTraditionally, Radiosity algorithms have been restricted to scenes made from planar patches. Most algorithms for computing form factors and the subdivision criterion for hierarchical methods implicitly assume planar patches. In this paper, we present a new radiosity algorithm that is solely based on simple geometric information about surface elements, namely their bounding boxes and cone of normals. Using this information allows to compute efficient error bounds that can be used for the subdivision oracle and for computing the energy transfer. Due to the simple interface to geometric objects, our algorithm not only allows for computing illumination on general curved surfaces, but it can also be directly applied to a hieararchy of clusters. Several examples demonstrate the advantages of the new approach.Item Building Telepresence Systems: Translating Science Fiction Ideas into Reality(Blackwell Publishers Ltd and the Eurographics Association, 1997) Fuchs, HenryMany people feel that at some time in the distant future it will be possible to see and interact with remote individuals so realistically that they will appear to be standing next to us, that it will also be possible for physicians to look inside their patients and see organs and tumors, as if they possessed Supermanâ s X-ray vision.Although we are far from the realization of such dreams, we are witnessing some encouraging progress toward them. For example, we understand that two aspects common to these systems are a) the acquisition and synthesis of complex 3D information (whether from cameras at a distant scene or medical imaging devices inside a patient), and b) reconstruction and presentation of the 3D information to the observer (whether a distant collaborator or a nearby physician). Early results from several institutions are encouraging.It is now possible to walk around distant scenes, although the visual data still needs to be preprocessed, the scene still needs to be static and the reconstruction still has gaps. It is possible to look inside patients, although with crude ultrasound imaging and with very limited visualization, or not naturally from the physicianâ s own point of view. It is not yet possible to view any of this kind of information with high degree of immersive 3D realism without wearing cumbersome visualization aids. Truly compelling realization of these long-held dreams will take careful analysis of the remaining problems, creative thinking about new approaches, and innovative and sustained development of the required acquisition and display technologies.Item Bulge Elimination in Convolution Surfaces(Blackwell Publishers Ltd and the Eurographics Association, 1997) Bloomenthal, JulesThe relationship between surface bulge and several implicit blend techniques, particularly those based on convolution of a skeleton, is discussed. An examination of branching skeletons reveals that for two and three-dimensional skeletons, the surface will be bulge-free if skeletal elements are sufficiently large with respect to the convolution kernel.Item Calendar of Events(Blackwell Publishers Ltd and the Eurographics Association, 1997) Greiner, GuntherItem Calendar of Events(Blackwell Publishers Ltd and the Eurographics Association, 1997)Item Calendar of Events(Blackwell Publishers Ltd and the Eurographics Association, 1997)Item Calender of Events(Blackwell Publishers Ltd and the Eurographics Association, 1997)