I’ve been using VRay RT GPU more and more over the last couple of weeks. While I know Vlado and team are working on getting Material ID and Render ID working on RT GPU as elements, is there a workaround in RT GPU to be able to have objects and materials render each as a separate pass? This way I can select fabrics on sofas and carpets, etc., which I seem to ALWAYS have to tweak when it comes to color correcting in Photoshop when providing the rendering to the Designer. I’d re-render, but it literally takes me 2 minutes when I have a Material ID.
You can use MultiMatte render element with RT GPU instead.
Thanks man. Let me ask, is there a way to use it? I have no idea, I just added it to two renderings and all it did was to come out black. 
How do you use this? I’m using 3.03.05.
You need to set object ID for your geometry. Then set the render elements colors to those ID numbers.
Note that MtlID won’t work with RT GPU and MultiMate pass.
Oh that makes sense. I’ll try that, but it sounds like one hell of a drawback for a scene with 998 objects. That means, even with a script I found to randomize the numbers, a good chunk of elements. Anyhow, whenever we get that Material ID and Render ID into use in RT, I think it will be the greatest thing to have happened in this planet since the invention of the wheel. 