Alpha Buffer

[medzo]

Hi

How can I save alpha buffer/pass (jpg format)? I can't find it it Render passes node. To be more clear, I need to use alpha buffer to cut out window glass in post production to insert background photo.

Thank you
Matej

[juanjgon]

The alpha channel is always included in the main beauty pass, so you extract it from this file. Only be aware that you need to enable the alpha rendering in the kernel node.

Thanks,
-Juanjo

[FrankPooleFloating]

For me (and maybe me alone) if it is just one single item I need isolated for post, I will sometimes just make a copy of my scene that is solely for isolating whichever mesh or material using render layers. If it is a particular material I need, I'll just split that off into a separate mesh real quick. So if this were me, I would likely make my window glass a separate object, give it a unique render layer ID number in my new scene, enable render layers in kernel node and hit F9, which would give me a perfect alpha (which you could make b/w from in PS if needed) in mere minutes. A total quick-and-dirty no-brainer with no need for passes... But it just depends on the scene. I find this efficient for one-off situations.