View Full Version : Mental ray light, diffuse pass, bad shadows

01 January 2012, 09:25 PM

I'm a bit new to rendering and I'd appreciate any help.

My trouble:
Area light with blackbody, shadows don't look correct in diffuse pass.

My setup:
I have a couple objects with mia_material_x_passes and a single light above the objects with a Mia_portal_light connected to my area light > Custom shaders > Light Shader, and a mib_blackbody plugged into the mia_portal_light.

If i delete the portal and blackbody connections, and use only a default area light, the diffuse pass with shadows looks correct. I'm guessing im missing something when trying to render passes with mental ray lights. I'm not getting the same soft shadows in the diffuse pass that i see in the master beauty pass. Can anyone help?


side question here. Area light with use light shape with portal light and black body is pretty noisy. To get smoother shadows, i need to turn up high samples? on some larger lights i've gone up to 128 samples and i still see some noise. Any suggestions?

01 January 2012, 01:47 PM
This is a bug with any light shader i found.

Reported it to Autodesk but no fix as of yet.

Posted stuff about it here:



05 May 2012, 04:59 PM
some problem, any ideas??? :(

05 May 2012, 12:14 AM
This should work fine with MentalCore render passes :thumbsup:

05 May 2012, 01:30 PM
but it is bug? or what?

05 May 2012, 06:50 PM
This is a bug with the AD framebuffers. Please report this and mark 'Critical' because it is. :-)

mental core uses its own modern framebuffers and does not suffer this problem.

05 May 2012, 06:55 PM
Sidenote: Try to refine which light shader breaks it at the most basic level and post it as a .ma file.

05 May 2012, 11:54 AM

if i check this button -
shadows locks correct..

Sidenote: Try to refine which light shader breaks it at the most basic level and post it as a .ma file.

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05 May 2012, 11:54 AM
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