shadow map banding

[Multiman]

This is a problem I encounter sometimes too. Its usually the bias setting but if you increase it enough to supress the patterns it often pushes the shadow too far away from the source. My only suggestions would be to tweak the shadow resolution along with the bias and if that doesnt help, either use area shadows (if you can stand the render time - otherwise bake them) or paint them in by hand.

cheers

DD

[ChrRambow]

The Shadowmap is way too low.

Try to increase the size of the map to 512x512 or 1024x1024
and increase the samplesize too ... for example to 9 or 14 .... to soften it again.

that should help ;)

Edit: ah i see you already got it at 750 x 750 ... then try to increase the samplesize.
Another possibility could be ... that the light source is too far away from the object...
that will cause more information for the shadowmap.

[tcastudios]

I am under the impression that Area Lights must use Area Shadow to work properly.
Try to skip the shadow from your area light and instead add SoftShadow shadowcaster light(s) instead.

Cheers
Lennart

[3DBond]

Don't mean to spam rodney, but I'm wondering where you got your scheme/icons.

[Newstream]

I find that unchecking the "Absolute Bias" (thereby gaining access to the greyed out Bias (Rel)) and increasing its percentage value to something in the order of 2-4 % usually takes care of the problem. Try it and see what happens.

Cheers / Alex

[Per-Anders]

Interesting, I responded to this earlier, i guess CGTalk had a glitch. Anyhow the problem is a combination of your bias, the sample size and the actual shadowmap resolution. Try using a spotlight for the actual shadow casting light this will make the best use of your shadow resolution otherwise it's spread out to cover whatever area your light covers, what you're seeing here are the pixels of the shadow map coming through your floor (again in combination with their depth and the shadow bias), the samples will help smooth things out by sampling surrounding pixels.

[rodney71]

Using a spotlight as a shadow caster seems to be the best solution. would never have guessed on my own. All the other options had too much of a down side, like shadow gets to soft by the time the stepping disappears. it does seem to make a lot better use of the shadow samples or whatever it is that generates the big alias steps in the shadow. in the mean time I went ahead with area shadows and had enough time, but i'm very glad to understand this as I have run into it numerous times.

thanks a whole bunch guys.

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