A hierarchical illumination algorithm for surfaces with glossy reflection
Larry Aupperle, Pat Hanrahan · 1993
We develop a radiance formulation for discrete three point transport, and a new measure and description of reflectance: area reflectance.This formulation and associated reflectance allow an estimate of error in the computation of radiance across triples of surface elements, and lead directly to a hierarchical refinement algorithm for global illumination.We have implemented and analyzed this algorithm over surfaces exhibiting glossy specular and diffuse reflection.Theoretical growth in light transport computation is shown to beO(n+k 3 ) for sufficient refinement, where n is the number of elements at the finest level of subdivision over an environment consisting ofk input polygonal patches -this growth is exhibited in experimental trials.Naive application of three point transport would require computation over O(n 3 ) element-triple interactions.