Alpha channel cut (and request).

[piotrglabski]

In our team, we have had the same workflow applied to hundreds of scenes for about 15 years. It consists of saving the rendering in one file and then using the alpha channel in photoshop.
Recently GPU rendering is prevailing and the lack of a rendered alpha channel is becoming more and more of a problem because it requires additional steps.
Is it somehow possible to get the same effect with GPU rendering while preserving the presented scene setup, i.e. so that VRB receives the alpha channel in one pass.
Is this something that can be added as a feature request? Or is this technically impossible to achieve in the Vray engine?
If this is the wrong channel please correct.

[hermit.crab]

Not sure if I understand. Based on the graphics, the sphere should contribute to the alpha in GPU too, and in fact, it does. There must be something else causing the differences. What host platform are you using? Better recreate the setup in 3d and attach the file here so we can take a look.

[piotrglabski]

Hi,
Basic setup: an object against the background with alpha contribution set to 0.
With Vray 7 alpha is present within VB
Switching to Vray GPU - alpha is NOT present.
Objective is to have alpha cut.
(I'm not allowed to attach *.max files, I'm attaching zipped file).

[hermit.crab]

Okay, just as I thought. Well, the Alpha Contribution parameter is not yet supported on the GPU, however, we do have an improvement request (internal tracker id: VGPU-2828 ). I'll add a bump on your behalf. For now, I suggest you use, f.e, VRayCryptomatte to create masks for whichever object you'd like.