Transparency and Alpha channels

[BBullo]

How do you render glass that allows you to save to a Tiff that saves the background as a channel?

If I do as I would in scanline, there is no channel saved.

Is it related to alpha contrabution under Vray properties?

[Morbid Angel]

can you be more clear as to what you are trying to ouput?

[BBullo]

I have an interior scene that has a section of glass looking out to the exterior.
I'm trying to get an alpha channel of the environment saved in the image.
ex. "tiff store alpha channel"
In the scanline days this would be set as you define a tiff image to be saved.
with vray glass(transparancy), there is no alpha channel saved for the environment.

[Morbid Angel]

hmm if I understand correctly you need to save the background in the pass, if thats so you need to use gbuffer vrayBackground.

[BBullo]

Right! -