Density estimation optimizations for global illumination

Abstract

Density estimation on the tangent plane (DETP) is a density estimation technique for global illumination. This technique is based on Photon Maps and provides increased accuracy when the surfaces are not locally smooth or continuous. However, the performance of the technique is limited by the large number of ray-disc intersections needed. Some optimizations which increase the performance of DETP have been devised. The first optimization works by creating a set of candidate rays for each radiance calculation. The second optimization uses spatial indexing of the discs around the radiance calculation points. An analytical study of the order of complexity of the algorithms, as well as an heuristic study of the calculation time for the different values of the parameters involved, has been performed. Some rules are given in order to identify the most suitable optimization for a given radiance calculation.