It is possible to render specular component in alpha channel in VRay?

[doark]

Hello everyone, I'm trying to do something that seems to have some trick!

I want to render the Specular component (the Specular highlight) in the alpha channel. This workflow very similar to the one used when the VRayMtlWrapper is used to Shadows -> Affect alpha.

It is possible to do this in VRay for Maya?

[joconnell]

What would you like to do with it after? Specular can contain colour information since it's the reflection of a light source (admittedly shadows can have colours too) so could you not just render the specular render element and then use that as an alpha channel in whatever comping package you're using afterwards by using the luma values of the spec channel as a mask or an alpha?

[Svetlozar Draganov]

There is a Specular Render element which holds the information about specular-reflections - it can be used to extract specular masks.
Rendering specular directly in alpha-channel is not possible so far.
Like joconnell mentioned , it would be useful to know what would you like to do with it - maybe we could suggest another approach.

[doark]

Sorry for the delay in answering the topic. (I was running with other works...)

Thanks for answering joconnell (BTW, thanks for the tutorial you posted on vimeo it was very understandable!). It was to be used in a montage of various characters (> 100) then I needed that output be directly specular in alpha-channel. I took into consideration in doing this in Nuke using luma values. But over time they had would not go have time to finish the job.

Svetlozar Draganov, Thank you for your attention. The first approach that you told was the first thing I tried, but it would be necessary further work comp. That would not be possible in the budget.