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Stochastic Transparency
August 2011 (vol. 17 no. 8)
pp. 1036-1047
Eric Enderton, NVIDIA Corp., Santa Clara
Erik Sintorn, Chalmers University of Technology, Gothenburg
Peter Shirley, NVIDIA Corp., Santa Clara
David Luebke, NVIDIA Corp., Santa Clara
Stochastic transparency provides a unified approach to order-independent transparency, antialiasing, and deep shadow maps. It augments screen-door transparency using a random sub-pixel stipple pattern, where each fragment of transparent geometry covers a random subset of pixel samples of size proportional to alpha. This results in correct alpha-blended colors on average, in a single render pass with fixed memory size and no sorting, but introduces noise. We reduce this noise by an alpha correction pass, and by an accumulation pass that uses a stochastic shadow map from the camera. At the pixel level, the algorithm does not branch and contains no read-modify-write loops, other than traditional z-buffer blend operations. This makes it an excellent match for modern massively parallel GPU hardware. Stochastic transparency is very simple to implement and supports all types of transparent geometry, able without coding for special cases to mix hair, smoke, foliage, windows, and transparent cloth in a single scene.

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Index Terms:
Rendering, transparency, shadow maps, deep shadow maps, stochastic sampling.
Eric Enderton, Erik Sintorn, Peter Shirley, David Luebke, "Stochastic Transparency," IEEE Transactions on Visualization and Computer Graphics, vol. 17, no. 8, pp. 1036-1047, Aug. 2011, doi:10.1109/TVCG.2010.123
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