Meeting AgendaMeeting Agenda| Date: | November 9th, 2005 |
| Location: | DC 1304 |
| Time: | 1:30 PM |
| Chair: | 
Yi Lin |
| Date: | November 16th | November 23th | November 30th | December 7th |
| Location: | DC1304 | DC1304 | DC1304 | DC1304 |
| Chair: | 
Andrew Lauritzen |
Curtis Luk |
Steve Mann |
Michael McCool |
| Technical
Presentation: |
Yi Lin |
Robin Liu |
Curtis Luk |
Steve Mann |
Abstract: Shadow maps are a widely used shadowing technique in real time graphics. One major drawback of their use is that they cannot be filtered in the same way as color textures, typically leading to severe aliasing. This paper introduces variance shadow maps, a new real time shadowing algorithm. Instead of storing a single depth value, we store the mean and mean squared of a distribution of depths, from which we can efficiently compute the variance over any filter region. Using the variance, we derive an upper bound on the fraction of a shaded fragment that is occluded. We show that this bound often provides a good approximation to the true occlusion, and can be used as an approximate value for rendering.
Our algorithm is simple to implement on current graphics processors and solves the problem of shadow map aliasing with minimal additional storage and computation. Unlike standard shadow maps, variance shadow maps can make use of hardware features such as anisotropic filtering and mipmapping, and support arbitrary prefiltering.
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