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Item Hardware Challenges for Ray Tracing and Radiosity Algorithms(The Eurographics Association, 1992) Jansen, Frederik W.; Kok, Arjan J. F.; Verelst, Theo; P F ListerComputer graphics algorithms and graphics hardware have mainly been developed along two lines: real-time display and realistic display. Real-time display has been achieved by developing dedicated hardware for projective, depth-buffer display algorithms.Increased realism has been achieved by ray tracing and radiosity algorithms,which generally are implemented on standard workstations because the complexity of the computation makes it difficult to implement these algorithms in hardware. Inthis paper we review these different approaches and discuss the feasibility of usingspecial hardware to enhance the radiosity and ray tracing computation. In particularwe will explore the use of the intersection of a frustrum of rays with patches in a sceneas a basic computational primitive for these algorithms and their implementation inhardware.K eywords and phrases: rendering, radiosity, ray tracing, graphics hardware, parallelprocessing.Item Adaptive Sampling of Area Light Sources in Ray Tracing Including Diffuse Interreflection(Blackwell Science Ltd and the Eurographics Association, 1992) Kok, Arjan J. F.; Jansen, Frederik W.Ray tracing algorithms that sample both the light received directly from light sources and the light received indirectly by diffuse reflection from other patches, can accurately render the global illumination in a scene and can display complex scenes with accurate shadowing. A drawback of these algorithms, however, is the high cost for sampling the direct light which is done by shadow ray testing. Although several strategies are available to reduce the number of shadow rays, still a large number of rays will be needed, in particular to sample large area light sources. An adaptive sampling strategy is proposed that reduces the number of shadow rays by using statistical information from the sampling process and by applying information from a radiosity preprocessing. A further reduction in shadow rays is obtained by applying shadow pattern coherence, i.e. reusing the adaptive sampling pattern for neighboring sampling points.