Structured Sampling And Reconstruction Of Illumination For Image Synthesis

An important goal of image synthesis is to achieve accurate, efficient and consistent sampling and reconstruction of illumination varying over surfaces in an environment. A new approach is introduced for the treatment of diffuse polyhedral environments lit by area light sources, based on the identification of important properties of illumination structure. The properties of unimodality and curvature of illumination in unoccluded environments are used to develop a high quality sampling algorithm which includes error bounds. An efficient algorithm is presented to partition the scene polygons into a mesh of cells, in which the visible part of the source has the same topology. A fast incremental algorithm is presented to calculate the backprojection, which is an abstract representation of this topology. The behaviour of illumination in the penumbral regions is carefully studied, and is shown to be monotonic and well behaved within most of the mesh cells. An algorithm to reduce the mesh siz..