vsm artifacts

i’ve implemented variance shadow mapping, but there are still some artifacts: when two or more occluders overlap, there is no shadow. these artifacts only appear if i filter the texture bilinear and/or apply a gaussian blur.

vsm with linear filtering, no artifacts:

vsm with linear filtering and gaussian blur:

the vsm code is 1:1 copied from the original paper (www.punkuser.net/vsm). any ideas how to get rid of this? vsm is pretty pointless if you cannot filter the shadow maps

btw i’m using 16bit floating point fbo’s.

AFAIK this light bleeding is a known problem with variance shadown maps.

[ www.trenki.net | vector_math (3d math library) | software renderer ]

yeah i know but has noone found a solution (or at least a hack) for this yet?

I spent some time on it, but never found a decent solution. It may be good for stuff where light bleeding isn’t very noticable (say for foliage). The best hack to get something semi-decent is to apply an s-curve function to the resulting shadow value, like shadow * shadow * (3.0 - 2.0 * shadow). This makes the artifacts less noticable, but also makes the shadow a bit less blurry for the amount of blur you applied to it.

hey that does help! if i apply that twice, i get rid of 90% of the artifacts! the shadows aren’t as blurry anymore, but still look very good. thank you very much!

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