Alpha with Vray Sky

[rusteberg]

Why is there a difference between alpha channels when rendering with vray sky?

Here is an example: same scene one lit with invisible dome, the other with sky in the 3ds max environment slot - each render saved as .png with alpha included

The alpha included with the sky render is different than the alpha rendered with the invisible dome light....



edit: I just noticed that if I put the sky map in the vray render "GI environment override" slot that I get the same alpha....

I guess this solves my problem.... just curious why the alpha channel gets bloated by a pixel or two when the sky map is in the 3ds max environment slot vs. the vray GI environment slot in the render settings panel.... (and I searched for a solution to this on the forum and didn't really find the answer I was looking for so maybe this is helpful...)

[rusteberg]

here's a better example..... sorry, but this has been driving me insane until just now

now, is there a way to include the background image applied in the vfb with the saved output? or does that have to be comped in post? seems to ignore that when saving to various image formats...

[kosso_olli]

Background image loaded in the VFB does not get saved into a file. Sadly.
The problem you are showing makes sense. When you put the sky into the 3dsMax environment slot, V-Ray is filtering the rendered shrub against the extremely bright sky. That is the white outline you see.
When you put the sky into the GI slot, V-Ray is filtering against the black background, which works much better. You would get quite the same if you comped it in any software, too.