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Many problems in computer graphics and computer vision require accurate global visibility information. Previous approaches have typically been complicated to implement and numerically unstable, and often too expensive in storage or computation. The Visibility Skeleton is a new powerful utility which can efficiently and accurately answer visibility queries(More)
Visualization of very complex scenes can be significantly accelerated using <italic>occlusion culling</italic>. In this paper we present a visibility preprocessing method which efficiently computes potentially visible geometry for volumetric viewing cells. We introduce novel <italic>extended projection</italic> operators, which permits efficient and(More)
Quadtrees constitute a hierarchical data structure which permits fast access to multidimensional data. This paper presents the analysis of the expected cost of various types of searches in quadtrees|fully speciied and partial match queries. The data model assumes random points with independently drawn coordinate values. The analysis leads to a class of(More)
Some very impressive results have been obtained in the past few years in plants and trees image synthesis. Some algorithms are largely based on the irregularity and fuzziness of the objects, and use fractals, graftals or particle systems. Others focus on the branching pattern of the trees with emphasis on morphology. Our concern here is the faithfulness of(More)
We analyse some recent approaches to the global illumination problem by introducing the corresponding <i>reflection operators</i>, and we demonstrate the advantages of a two-pass method. A generalization of the system introduced by Wallace <i>et al.</i> at Siggraph '87 to integrate diffuse as well as specular effects is presented. It is based on the(More)
Visibility computations are central in any computer graphics application. The most common way to reduce this expense is the use of approximate approaches using spatial subdivision. More recently analytic approaches efficiently encoding visibility have appeared for 2D (the visibility complex) and for certain limited cases in 3D (aspect graph, discontinuity(More)
Data structures that handle very complex scenes (hundreds of thousands of objects) have in the past either been laboriously built by hand, or have required the determination of unintuitive parameter values by the user. It is often the case that an incorrect choice of these parameters can result in greedy memory requirements or severely degraded performance.(More)