Advanced Radiance Estimation For Photon Map Global Illumination

Abstract

We present a new method to compute radiance in photon map based global illumination simulation for polygonal scenes with general bidirectional scattering distribution functions (BSDFs). Our new radiance estimation uses the actual geometry in the neighborhood of the illuminated point, and does not assume that the nearest neighbor photons lie in the same plane as the point, nor that they are distributed in a circular area around that point. This allows us to achieve accurate indirect illumination by direct visualization of the photon map - which is especially important for the simulation of caustics(LS+DS*Epaths) - even in the vicinity of edges and corners of objects, and on surfaces with differently oriented small geometric details.