Spherical Light Integration over Spherical Caps via Spherical Harmonics

Abstract

Monte Carlo(5.47s) Ours(5.20s) Reference Monte Carlo(6.57s)/Ours(7.01s)/Reference Figure 1: Equal time comparison of Monte Carlo rendering and our method. This breakfast scene is lit by 2 sphere lights (left) and 1 quad light (right). Our method uses order 16 SH expansions for the rough gold BRDF (highlighted on the left) and order 8 for diffuse BRDF. We compare relative MSE numbers for full image (top) and several insets (bottom). Our method can outperform Monte Carlo sampling (MIS) method for direct lighting with good approximation of low frequency BRDF.