CGTalk - VRay Dirt bias-y

stussy

01-23-2012, 08:32 PM

Hello, can somebody explain me what is wrong here? I don't get it.

I am using a VRay Material with Dirt in the diffuse channel. I want to push the dirt into a specific direction. For this one can use the bias x y z option. But when I am using values higher then 0.9 or -0.9 the surfaces that are facing into that direction are becoming black. It seems not to be a matter of scale. So, -0.9 is working, -1.0 not !! I tested it in 3ds Max with VRay 2.0 too and it is working (Z) !! where is the problem in Maya?

http://img843.imageshack.us/img843/8465/vraybias9.th.png (http://imageshack.us/photo/my-images/843/vraybias9.png/)

thx

stussy

gcr113

01-24-2012, 08:56 AM

Bias values greater than 1 work fine for me. I bet your normals are reversed.

visua

01-24-2012, 10:38 AM

What happens if you lower your radius? Coz you will surely have the same problem in max if the radius is larger than the object is long so to speak.

stussy

01-24-2012, 08:14 PM

I did a new test. The normals are facing correct to the outside, the scale of the box is bigger than 1.0. But still, when bias is bigger than 0.9 the lower faces are getting black :shrug: I don't get it.

http://img846.imageshack.us/img846/9163/61721761.th.jpg (http://imageshack.us/photo/my-images/846/61721761.jpg/)

http://img11.imageshack.us/img11/9779/58633411.th.jpg (http://imageshack.us/photo/my-images/11/58633411.jpg/)

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01-24-2012, 08:14 PM

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