“Precomputed importance sampling”

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    Precomputed importance sampling


    We present a method for cosine-weighted importance sampling of environment maps. Our technique has no runtime overhead. It is well suited for real-time ray tracing and for algorithms that generate only a few shadow rays per primary ray. Both memory consumption and preprocessing time are very low. Basically, our algorithm precomputes a large number of light samples for different surface orientations and picks randomly from them during rendering.


    1. Clarberg, P., and Akenine-Möller, T. 2008. Practical Product Importance Sampling for Direct Illumination. Computer Graphics Forum (Proceedings of Eurographics 2008) 27, 2, 681–690.
    2. Cline, D., Egbert, P. K., Talbot, J. F., and Cardon, D. L. 2006. Two stage importance sampling for direct lighting. In Rendering Techniques 2006 Eurographics Symposium on Rendering, 103–113.
    3. Lawrence, J., Rusinkiewicz, S., and Ramamoorthi, R. 2005. Adaptive numerical cumulative distribution functions for efficient importance sampling. In Rendering Techniques 2005 Eurographics Symposium on Rendering, 11–20.
    4. Pharr, M., and Humphreys, G., 2004. Infinite area light source with importance sampling. on www.pbrt.org.

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