Importance Driven Path Tracing using the Photon Map

Abstract

: This paper presents a new importance sampling strategy for Monte Carlo ray tracing in which a rough estimate of the irradiance based on the photon map is combined with the local reflection model to construct more efficient probability density functions that can be used in an importance sampling scheme. The algorithm gives unbiased results, handles arbitrary reflection models and it is particularly efficient in scenes with highly non-uniform indirect illumination. Initial results and comparisons with traditional importance sampling strategies indicate a reduction in the noise level of more than 70% Key Words: Global Illumination, Path Tracing, Importance Sampling, Photon Map 1 Introduction Photorealistic rendering requires accurate simulation of global illumination and much work has been done in this area in the last 10 years. The problem was actually solved in 1986 by Kajiya [6] using a method called path tracing. This method is basically a brute force Monte Carlo simulat...