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mister3d
09-22-2009, 05:38 AM
H guys. I need to render a transparent object with a background refraction but that the background alpha was not present. I know how to make it in vray, but need this in mental ray. I use 3ds max 2009. I can't get how to use matte shader in mental ray. Can somebody explain?

ndeboar
09-23-2009, 06:14 AM
Hey,

I dont think i totally understand the question, but to attempt to help:

Anything with refraction doesn't have an alpha channel, ill always be matte. If you have a background image, again the object wont have an alpha (i gets treated like a plane with a texture).

Maybe just do an ID pass? Do a render of the object with a surface shader, and just use that as the alpha in comp?

That probably didnt help :) Maybe post a pic.

Nickl

mister3d
09-29-2009, 10:46 AM
Hey,

I dont think i totally understand the question, but to attempt to help:

Anything with refraction doesn't have an alpha channel, ill always be matte. If you have a background image, again the object wont have an alpha (i gets treated like a plane with a texture).

Maybe just do an ID pass? Do a render of the object with a surface shader, and just use that as the alpha in comp?

That probably didnt help :) Maybe post a pic.

Nickl
Hi Ndeboar, and thank you for the reply.
In mental ray with arch&design shader you can set refraction propagates alpha (or something very similar in name) and the alpha will support transparency.
What I need is simply a matte object, i.e. that it won't affect the alpha. In that case it was the background plane. If I'm not mistaken, if using something as a matte object which is seen through transparency, it will be seen through a transparent object, as well as in reflection.

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09-29-2009, 10:46 AM
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