“Correlated Visibility Sampling for Direct Illumination”

Combined sampling strategies for direct illumination such as Veach&Guibas [1995] and bidirectional importance sampling [Burke 2004] take into account the importance of both the incident illumination, as well as the surface BRDF. These techniques achieve low variance in unoccluded regions. However, the resulting images still have noise in partially occluded regions as these techniques do not take visibility into account (Figure 1, left). This work aims to take visibility into account in the sampling process for partially occluded regions, thereby improving the quality of the shadowed regions (Figure 1, right).

Burke, D. 2004. Bidiectional Importance Sampling for Illumination From Environment Maps. Master’s thesis, The University of British Columbia.
Veach, E., and Guibas, L. 1995. Optimally combining sampling techniques for monte carlo rendering. In Proc. of ACM Siggraph ’95, 419–428.
Veach, E., and Guibas, L. 1997. Metropolis light transport. In Proc. of ACM Siggraph ’97, 65–76.