Reflection Alpha

V-Ray V-Ray for Maya General
1

Hello - Is it possible to get an alpha channel for the reflection contribution?

An example of a need for this, is rendering a ground reflection to be composited over a live action plate.

Vray gets halfway there with alphas’ for shadows using the “Matte Surface Alpha Contribution -1” workflow, but falls short in delivering an alpha for reflections… or is there another method for generating a reflection alpha that I’m missing?

Regards
Chris

2

Hi,
Use VRay dirt in reflection mode.

3

Thanks Deex, that is a good tip/method, and will be very useful for 90% of the time.

I guess it gets hard to manage in shots with multiple reflective surfaces with different glossiness values… but like I said, great work-around for this Vray Shortcoming.

Thank you very much
Chris

4

This is already implemented in Vray for 3DSMax.
We have it already into our “to do” list for Maya - but like always I couldn’t tell when it will be released - until then the only way is to extract reflection masks is with Vray Dirt in reflection mode.

5

hello
neither the object propperties nor the material wrapper work for alpha contribution of reflections . ..

I’m used to work with the mental ray matteshadow production shader - this does the trick perfectly - but no idea how to get this done with vray.
just want to render a whiteroom with just reflections from object on perfekt white floor?!

sorry for hijacking this thread ^^

br mayanic

6

Just make what ever you want to reflect surface shader RGB RED and disable all lights.Then just render beauty pass and use R channel for ur mask. Should work just fine. Remember to play with reflection values.