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Efficient Shadow Computations in Ray Tracing
September/October 1993 (vol. 13 no. 5)
pp. 78-83

Two techniques to speed up shadow computations in ray tracing are examined. The first, atomic adaptive sampling, is intended for any light type, such as directional, spot, point, linear, and area lights, in antialiasing, while the second, plane-vertex checking, specifically accelerates shadow computation of linear and area lights. The basic ideas can be extended to other ray types and, for the plane-vertex check, to radiosity applications as well. Existing surveys explain the fundamentals and provide references to intersection culler and shadow algorithms.

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Andrew Woo, "Efficient Shadow Computations in Ray Tracing," IEEE Computer Graphics and Applications, vol. 13, no. 5, pp. 78-83, Sept.-Oct. 1993, doi:10.1109/38.232102
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