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republicavfx
09-12-2007, 06:11 PM
im working on a scene with alot of rocks falling of a cliff and down the side and land on a couple of people

i made a hi detail proxy cliff and added useBackground shader but got horribly artifacted shadow pass

i discovered if i made a very simple plane LOW poly type cliff i have no artifacts

but when i subdivid plane then added detail to make nicer shadows i get terrible artifacts

almost like holes in the mesh. thought maybe was a problem with uvs, or normal smoothing, or intersecting faces...but the mesh has none of these issues.

is this a known bug? i tried simpler test scenes and whenever i subdivide mesh and sculpt detail my shadows on useBackground shader go to hell.\

\help!

AlphaJoe
09-12-2007, 09:59 PM
I get odd results sometimes with the UseBackground shader. Could you post a couple of renders?

One thing you should check is to make sure that you have the reflections turned off on the shader. I have seen and done this myself a few times. By default the UseBackground shader has .5 reflectivity.

alexx
09-13-2007, 08:30 AM
i already reported some bugs to autodesk relating to the use background shader and especially shadow maps.

unfortunalely mental ray seems to use the same implementation, so both renderers produce similar and wrong results :/

cheers

alex

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