CGTalk - Mental Ray, GI and Final Gathering

View Full Version : Mental Ray, GI and Final Gathering

MikeRhone

09-12-2002, 03:15 AM

I have been working with getting a mental ray GI/Final gathering render together, but I am having problems with the shadows ending up too grainy. I can increase the the aliasing of the shadow via the shadowmap resolution, but I cant change the grainy look. Does anyone have any advice on what setting I need to tweak to get a nice gradual shadow?
http://www.wingman.ca/deb/grainy.jpg

I am also having probelms with the inside of my characters mouth rendering out illuminated. I've decrease the amount of times the photons bounce to 2 to try and reduce the amount of light getting into the mouth, but that doesnt seem to make any difference. Does anyone know what I could be doing wrong?

Mike R

Wigaru Wiyamoto

09-12-2002, 04:47 AM

Well, I don't know diddly squat about MR. For the shadows I'm sure some setting needs to be increased. :shrug:

As for the mouth, have you tried placing a negative light inside the mouth?

MikeRhone

09-12-2002, 07:11 AM

I had thought about the negative light in the mouth, but I consider that to be a last resort, as I'de like to know exactly where all this extra light is coming from.

Lol. As for
"For the shadows I'm sure some setting needs to be increased. "

Hehe, I figured THAT much, i just dont know what to adjust. Upping the photons doesnt help... Increasing the Dmap doesnt help... Any other suggestions?

Mike r

alphatron

09-12-2002, 06:24 PM

Perhaps try and tone down the softness in the Mental Ray shadow map settings for the light? I frequently have this problem as well.. the only way to get great looking soft shadows in MR for Maya is to use raytracing, which is painfully slow.

For the inside of the mouth, perhaps turn off global illumination receiving on the areas that are too illuminated.. or maybe darken the shader on the inside of the mouth. I've also had this problem where areas that should be dark or shadowed are instead brighter, it's a Final Gather problem.

SheepFactory

09-12-2002, 07:29 PM

the mouth glow is because of final gathering.

i believe in order to avoid it you have to make the Incadescense of the mouth material totally black.

hope this helps.

CGTalk Moderation

01-13-2006, 04:00 PM

This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.