mactoons
03-18-2009, 05:27 AM
I am not sure if this is a common problem or not but I could not get a separate shadow pass rendered for shave and a haircut shadows. I basically just wanted the shadows on the character geometry to composite in post with the rest of the character and hair. You are supposed to be able to accomplish this by just checking "shadow matte" in the shave globals. The problem I had was this only gave me shadows from 1 light in my scene and I needed it to use 3 lights. I think it is some sort of bug, I'm using maya 08. But I figured out a workaround that would give me shadows from all the lights in my scene.
What I did was set up a render layer that had all the shaders on the character (where I wanted the shadows) as a basic white lambert and all of the background geometry that I didn't need shadows on I set to a "Use Background" shader from maya. Then in order to get the shadows I rendered this in one pass without any of the hair turned on at all so I just got a basic white lambert shaded image with no shadows and then I rendered it again with the hair on (but not compositing, I just rendered the hair to the output dir) and this gave me that same lambert shaded geo but now with the hair shadows also. Then I brought those 2 images into after effects (can be done in photoshop for single frames) and layered the 1 image on top of the other and put the blending mode as "Difference" (or "Difference (Classic)" in AE) and this gave me just the shadows that I could then use as an alpha for the shadows to composite with the rest (the character pass, bg, hair, etc).
Hope this makes sense and might help someone out. Let me know if you have any questions. I was rendering my hair pass and hair shadow pass with Maya Software renderer, although this probably would work for MR also.
What I did was set up a render layer that had all the shaders on the character (where I wanted the shadows) as a basic white lambert and all of the background geometry that I didn't need shadows on I set to a "Use Background" shader from maya. Then in order to get the shadows I rendered this in one pass without any of the hair turned on at all so I just got a basic white lambert shaded image with no shadows and then I rendered it again with the hair on (but not compositing, I just rendered the hair to the output dir) and this gave me that same lambert shaded geo but now with the hair shadows also. Then I brought those 2 images into after effects (can be done in photoshop for single frames) and layered the 1 image on top of the other and put the blending mode as "Difference" (or "Difference (Classic)" in AE) and this gave me just the shadows that I could then use as an alpha for the shadows to composite with the rest (the character pass, bg, hair, etc).
Hope this makes sense and might help someone out. Let me know if you have any questions. I was rendering my hair pass and hair shadow pass with Maya Software renderer, although this probably would work for MR also.