Issue 2
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Item Implicit Representations of Rough Surfaces(Blackwell Publishers Ltd and the Eurographics Association, 1997) Hart, John C.Implicit surface techniques provide useful tools for modeling and rendering smooth surfaces. Deriving implicit formulations for fractal representations extends the scope of implicit surface techniques to rough surfaces. Linear fractals modeled by recurrent iterated function systems may be defined implicitly using either geometric distance or escape time. Random fractals modeled using Perlinâ s noise function are already defined implicitly when described as "hypertexture."Deriving new implicit formulae is only the first step. Unlike their smooth counterparts, rough implicit surfaces require special rendering techniques that do not rely on continuous differentiation of the defining function. Preliminary experiments applying blending operations to rough surfaces have succeeded in an initial attempt to overcome current challenges in natural modeling. The grafting of a stem onto the base of a linear fractal leaf continuously blends smooth detail into rough detail. The blend of two textured cylinders interpolates geometric bark across branching points in a tree.Item Join Now!(Blackwell Publishers Ltd and the Eurographics Association, 1997)Item An Efficient Code-Based Voxel-Traversing Algorithm(Blackwell Publishers Ltd and the Eurographics Association, 1997) Zalik, Borut; Clapworthy, Gordon; Oblonsek, CrtomirItem Hierarchical Radiosity for Dynamic Environments(Blackwell Publishers Ltd and the Eurographics Association, 1997) Shaw, ErinThis paper extends the hierarchical radiosity method to environments in which geometry and surface attributes can be changed dynamically. New algorithms are presented for maintaining an appropriately-sized mesh and speeding the construction of the corresponding linear system. Mesh folding, the unrefinement of a mesh, is used to optimize mesh size while maintaining a specified error tolerance. Two new interactions are introduced: shadow links guide local shadow clean up after a change in geometry and ghost links guide global mesh folding after a change in surface attributes. The algorithms stabilize the memory requirements of dynamic scenes. Different types of interactions are analyzed to determine how they are affected by changes in geometry. A dynamic scene-partitioning scheme called a motion volume, used in conjunction with a three-dimensional clipping algorithm, provides a fast way to cull interactions that do not need to be updated. The algorithms are demonstrated on several sample scenes.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 Editorial(Blackwell Publishers Ltd and the Eurographics Association, 1997) Coquillart, Sabine; Seidel, Hans-PeterItem Calender of Events(Blackwell Publishers Ltd and the Eurographics Association, 1997)Item Contents(Blackwell Publishers Ltd and the Eurographics Association, 1997) -Item Perceptually-Driven Radiosity(Blackwell Publishers Ltd and the Eurographics Association, 1997) Gibson, S.; Hubbold, R. J.Item Image Credit to G. Elber(Blackwell Publishers Ltd and the Eurographics Association, 1997) Gibson, S.; Hubbold, R. J.Item 1998 Cover Competition(Blackwell Publishers Ltd and the Eurographics Association, 1997)Item Book Reviews(Blackwell Publishers Ltd and the Eurographics Association, 1997)Item Network Service(Blackwell Publishers Ltd and the Eurographics Association, 1997)