matte and irradiance map

[AVATAREA]

I have tried just about everything to get a matte I am using to receive a shadow from a spherical VrayLight and it just wont show up. Anyone got any ideas before I tear whats left of my hair out ?

[AVATAREA]

addendum

This may not be the appropriate way to approach this, but I'm used to
rendering passes in scanline.

My questions is: How can I get a matte object
to accept the irradiance map calculations? As of right now, no .vrmap info
renders on a matte. I'm compositing on a background and need the darker GI info to be saved in my .tga file.

[gilpo]

Right-click object to be made matte. Select VRay Properties.

Set it up like this:

Matte Object: Checked
Alpha Contribution: -1
Shadows: Checked

Make sure you are rendering with a black background. Save as TGA with a pre-multiplied alpha.

That should be all you need. That's all I do when we composite.

Good Luck,
Matt

[vizbiz]

The black background (or any background other than your enviroment) still seems to have pixel bleeding, or a halo around the edge. How do you work around this, or do you have the same problem?

[joconnell]

It depends on what program you use - photoshop strangely is really bad at dealing with alphas - there is a remove black and white matting option in the layer menu. Also try rendering with straight alphas and see if that helps.

[vizbiz]

I'll give that a shot .....

I also wanted to ask about losing the shadow and amb occlusion darkness when rendering on a matte object. For example when rendering against a matte, the shads or nowhere near as dark as a visible object.

I did a test, and I would have to copy my image over itself 5 times, to get the equivalant shadow depth. Perhaps my approach to compositing is out dated though. V-ray newbie