View Full Version : Bump (sampling?) again, question to the pro's here

12 December 2006, 12:38 AM
Hi all,

Basically, I've written a very simple "layered shader" which outputs different layers into different frameBuffers, sort of what ctrl_buffers does.

What I found now is that bump maps (at least procedurals) seem to get sampled differently depending on wether I plug my shading network into the "miMaterialShader" attribute in the Shading Group or the maya default "surfaceMaterial". Does anyone have an idea as to why this would happen ?

Please have a look at the screenshot, you'll see what I mean. I sort of feel that I still don't completely understand how mental ray handles bump mapping and what the bump mapping calculations of a lambert shader have to do with the shading group ???

It would be really cool to find out what's going on here, basically because I have to "convert" a lot of assets which previously have been rendered with MS to MR. And they more or less have to look similar...

PS: To reconstruct this, just build two similar networks, once with just simple maya nodes and one with the bump combiner in the end and compare the result...

12 December 2006, 05:58 AM
For anyone interested in an answer to this issue (thanks to Pavel aka puppet), have a look here :

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12 December 2006, 05:58 AM
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