“Bidirectional Importance Sampling for Illumination from Environment Maps”

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    Bidirectional Importance Sampling for Illumination from Environment Maps


    Image-based representations for illumination are able to capture complex real-world lighting that is difficult to represent in other forms. To date, the direction of most work for sampling from lighting has been an importance sampling strategy based on the energy distribution in the EM. This approach performs poorly for highly specular surfaces, where samples have a low probability of lying within the specular lobe. Similarly, if importance sampling is performed solely from the BRDF of the surface, then the sampling will not perform well for high-frequency EMs. We, therefore, introduce bidirectional importance sampling, a method that samples visibility according to an importance derived from the product of BRDF and EM illumination.


    Agarwal, S., Ramamoorthi, R., Belongie, S., and Jensen, H. W. 2003. Structured importance sampling of environment maps. ACM Trans. on Graphics 22, 3 (July), 605–612.
    Veach, E., and Guibas, L. 1995. Optimally combining sampling techniques for monte carlo rendering. In Proc. of ACM Siggraph ’95, 419–428.

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