CGTalk - Need help bouncing light back to it's source

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recklessronin

07-09-2007, 03:15 PM

Howdy.

It's been a long time since I rendered anything but I need to do it now. I set up some lights and have them at the intensity I want but unfortunately it's not bouncing the light back up so it looks kind of wierd. The attached images will show what I mean.

Also, I'm getting some weird shading effects. I'm rendering with Maya Software but the same thing happens when rendering with Mental Ray. On the first image there are areas on the pillar in the foreground where the shadow is very pixillated. I have "use depth map shadows" selected on each light and a resolution of 512. I'm just looking for nice soft shadows, which are there for the most part but I don't want those wierd pixillated shadows. Is this a setting that is to be made on the light itself or in the render settings?

http://www.flickr.com/photo_zoom.gne?id=761164717&size=o
http://www.flickr.com/photo_zoom.gne?id=761165053&size=o

Thanks for your help.
~rr

living3d

07-09-2007, 03:30 PM

You should use Global Illumination feature in mentalray rendering to get all looking good.

edit: and if you don't want GI you may use point lights with quadratic falloff instead of your spotlights.

recklessronin

07-09-2007, 04:06 PM

Thanks I'll try that out when I get home.

I meant to ask, would adding extra point lights between the light source and ground be a good idea?

living3d

07-09-2007, 04:14 PM

First of all, try what i have suggested before. If it won't work the way you want you may add a few fill lights. ;)

recklessronin

07-12-2007, 02:14 PM

Thanks for the help Living3D. The global illumination didn't work quite as well as I'd have liked so I'll try the other thing this weekend.

SanjayChand

07-12-2007, 03:05 PM

create a bunch of directional lights aimed at the black areas of your scene with varying shades, and/or create some point lights with a cubic decay rate.

Render out every light seperately and then comp them togethor so you can control each individual light color.

Seperating the lights into passes is a great way to fake GI, that and also with an ambient occlussion pass.

If you want less artifacts, then increase your DMap size.

recklessronin

07-13-2007, 04:55 AM

Thanks aryaFX. What does increasing the DMap size do exactly? I mean I know it would remove a lot of the jaggies, but other than longer render times are there any other performance impacts?

SanjayChand

07-13-2007, 07:49 AM

You should enable disk-based depthmaps and set it to "re-use", as this way it will only calculate the depthmap once and re-use it for every frame. Depthmaps are light-based, not camera based so if you have anything moving through the light with the depthmap then you have to re-calculate it.

There will probably be some perfomance hit initially but if you re-use the depthmaps then it shouldnt be too bad at all.

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