Super basic question about Matte

[PSVisuals]

I'm trying to take the image below, and change the background to a Matte so I can replace it with another color in post.



I set the object like this in the Vray properties.



Now my diffuse and Alpha channel look like this, which I think is incorrect.





And when I load it in Photoshop (with alpha channel) and put a new background behind it, I get this.



So this is clearly incorrect. The nice big shadows in the back are missing, and the GI in the front is completely missing. Is there some way to simply remove the diffuse element of the background while keeping shadows, GI, reflections, etc?

[tashko.zashev]

Hi,

Would it be possible to attache your scene file to see your lighting setup?
The matte object should not be visible in the diffuse render element. Also it looks like the GI shadows are not added to the alpha channel.

I suppose that this is with V-Ray 3.00.07.

[PSVisuals]

Here is a basic version of the scene. I didn't do any of the Matte settings, but I can't really figure out what needs to be done. The main thing missing from all matte objects I make is the GI color and shadows. Regular shadows usually work fine, and last night I got reflections working as well. But still can't get the GI color to show up when I save the image with an alpha channel.

Max file is here.

Save Link As

[tashko.zashev]

Thanks for the file.

For this setup I will advice you to uncheck Visible to GI option instead of using the "Generate GI" one.
Here are screenshots of the result:



I assume this is the final result that you are expecting to achieve.

[PSVisuals]

It's saying "invalid attachment" when I click the links you posted, sorry.

[tashko.zashev]

I'm attaching the files again.

[stef.thomas]

Does it really need to be a matte object if you're only planning on changing the colour? You could just set alpha of plane to zero and use that to get mask for colour correction in post. Matte would really only be useful if you were wanting to overlay on top of a background image.