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JaMo
04-02-2006, 04:33 PM
ok im going to try here since no one in the other forum knows exactly whats going on.

im trying to render in 2 passes, a color pass and a shadow pass. the image on the left is rendered with no passes which is how i want the image to turn out. the image on the right is composited with a color pass and a shadow pass. for some reason when i render in passes the shadows are bieng rendered differently.

im using maya 6.5,maya software render, raytraced shadows
im using AE 5.5 for compositing. im laying the shadow pass on top of the color pass.

here is the other post with more info http://forums.cgsociety.org/showthread.php?t=340225

http://www.geocities.com/feedback3d/example2.jpg

jeremybirn
04-02-2006, 04:44 PM
The Maya renderer's shadow passes often include some extra junk from areas where a light was beyond the terminator anyway, so the shadow doesn't matter much. If you render a separate shadow pass for each light, and a separate pass for the light being shadowed, then multiply each light with the shadow pass that goes with it, the problem would be avoided. It's just if you tried to do a shadow pass of the attached shadows with more than one light at a time in the same shadow pass that the extra junk would catch up with you. Separating out your shadow passes is a good idea anyway, otherwise you wouldn't have separate control over the shadow color, blurring, etc.

BTW, if you want your final product to look the way it looks in one pass, why would you be splitting this into more than one pass?

-jeremy

JaMo
04-02-2006, 04:50 PM
The Maya renderer's shadow passes often include some extra junk from areas where a light was beyond the terminator anyway, so the shadow doesn't matter much. If you render a separate shadow pass for each light, and a separate pass for the light being shadowed, then multiply each light with the shadow pass that goes with it, the problem would be avoided. It's just if you tried to do a shadow pass of the attached shadows with more than one light at a time in the same shadow pass that the extra junk would catch up with you. Separating out your shadow passes is a good idea anyway, otherwise you wouldn't have separate control over the shadow color, blurring, etc.

BTW, if you want your final product to look the way it looks in one pass, why would you be splitting this into more than one pass?

-jeremy

well ive had problems with shadows in the past so i wanted more control and i plan to adjust brightness,contrast,levels,etc on my models(not so much for this model)

im sorry but i do not quite understand your reply. i have like 3 or 4 lights set up in the scene but only the key light i beleive has the shadows turned on. im not sure what you mean by composite the light with its shadow.

jeremybirn
04-02-2006, 05:09 PM
well ive had problems with shadows in the past so i wanted more control and i plan to adjust brightness,contrast,levels,etc on my models(not so much for this model)

im sorry but i do not quite understand your reply. i have like 3 or 4 lights set up in the scene but only the key light i beleive has the shadows turned on. im not sure what you mean by composite the light with its shadow.

OK, great, only 1 shadow. Then render the key light as a pass, the non-shadowing fill lights as another pass. Composite the key light with the shadow pass, then add the fill lights. If the shadow artifacts you're looking at are all beyond the terminator of the key light, then the shadow pass would only darken a part of the key light pass that was already black.

-jeremy

JaMo
04-02-2006, 05:12 PM
OK, great, only 1 shadow. Then render the key light as a pass, the non-shadowing fill lights as another pass. Composite the key light with the shadow pass, then add the fill lights. If the shadow artifacts you're looking at are all beyond the terminator of the key light, then the shadow pass would only darken a part of the key light pass that was already black.

-jeremy

ok im a little confused about rendering light. im assuming you mean delete all the lights(or turn them off) but the key light and renderout the color and shadow pass. then render out the other lights except the key light into a single color pass? composite the 2 color passes and the one shadow pass?

im sorry im confused. if my assumption is wrong is there a tutorail on rendering out light?

jeremybirn
04-02-2006, 05:21 PM
ok im a little confused about rendering light. im assuming you mean delete all the lights(or turn them off) but the key light and renderout the color and shadow pass. then render out the other lights except the key light into a single color pass? composite the 2 color passes and the one shadow pass?

im sorry im confused. if my assumption is wrong is there a tutorail on rendering out light?

Yes, that's basically it. When you upgrade to Maya 7 you'll be able to define render layers with different membership, but in Maya 6.5 it's probably easiest to set them up manually by hiding different lights.

-jeremy

JaMo
04-02-2006, 05:23 PM
Yes, that's basically it. When you upgrade to Maya 7 you'll be able to define render layers with different membership, but in Maya 6.5 it's probably easiest to set them up manually by hiding different lights.

-jeremy

ah ok. one last question on this subject. if i were using MR would i even be having this problem?

btw thanks for your help. :) (i may have another question soon)

jeremybirn
04-02-2006, 06:23 PM
ah ok. one last question on this subject. if i were using MR would i even be having this problem?

Maybe. The amount of self-shadowing just beyond the terminator will vary with MR vs. Maya renderer (or with dmap shadows with your dmap bias or mid dist setting), but the basic problem that you're using a mask of the key light shadow to darken all of your other lights could cause different & often funny results in the comp no matter what renderer.

-jeremy

JaMo
04-03-2006, 01:49 AM
thank you for your help.

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