mmmaya mmmentalray mmmaterials

noritsune

hey there,

maya/mental ray specific question here. in a nutshell, sometimes mental ray will screw up the materials assigned to the faces of a given model. check out these renders:

maya viewport
maya software render
mental ray + FG

whats goin on?? I hope someone has seen this issue before or knows how to correct it. it's making it hell to get any good beauty renders. using Maya 7 here.

thanks!

Daz

That is really bizarre. I have never seen that before. What kind of shader is it?

noritsune

simple lamberts and blinns! it's insane! the most complex one has a spec mask plugged in. and sifting through mental-ray specific forums has gotten nowhere, I figured I'd ask on here.

Daz

Nothing weird to do with UV sets is it? No that wouldn't really make any sense. Somehow mental ray is confused by your polygons material assignments. Have you tried just making a cube and doing some simple tests?

malcolm

I have seen this malarkey before, I think it is new to Maya 7, some dude that sat beside me for a while had this problem every ten minutes, unfortunately I'm not sure how he was creating it. I've never encountered it myself?

noritsune

yeah hrrrm. I might switch back to maya 6 or 6.5, I never had the problem there and I actually havent found anything I'm especially attached to about maya 7 yet (except for that nifty camera-zoom when you frame up on an object! whee!).

Daz, oddly this problem only shows up on specific meshes (and all instances of that mesh). assigning a new material to the whole mesh, not just all the faces, will fix the problem... but it will resurface after assigning different materials to different faces, and adjusting UVs. the only way to kill the problem permanently is to re-build every suffering mesh, and that's hardly a solution! argh.

malcolm

Just started using mentalray again in Maya7. I've incountered a similar problem, my render was coming out with the wrong materials applied to the model, even though I had an exact duplicate of the model beside it rendering fine. The problem may be old shading group connections to your geo. Check your model in the hypergraph and if you see any connections to shading groups that you are not using delete them and the render should be fixed. My model had 2 materials applied and was rending with one material that was the not supposed to be on the model. Deleting the connection to the wrong material fixed the render.

Striff

Only thing that I can recomend is either re-installing Maya, or chaning the name of your maya folder in your documents to something like "maya2" which forces maya to make a new folder during its next startup, this is reset all your settings. See if that fixes your problem, and if it does, gradualy add back some of your scripts, etc to your new maya folder until you encounter the problem again..that way you know what file is causing it.

Ive had many weird things happen and have been able to fix them doing that.

Tulkamir

Not that it'd fix the problem, but if you are just assigning materials to the separate faces of a single object, you could try to extract the faces so that they are all separate objects, then apply the materials to thos objects. Not exactly the best fix, and it could give some funny seams depending on how your mesh is broken up, but it's a thought.

Also, try exporting the mesh without materials, then importing it back into a new scene and re-applying the materials maybe?

(That is if the stuff already said doesn't work).

Good luck.