Best way to create a matte for Vray Light objects?

[davision]

I have some Vray Light objects that I want to isolate so I can apply a glow to them in After Effects. I set the Vray Lights Object ID to 2, but the Multimatte render element is not picking them up? (Bummer.)

So, what is the best way to create a matte for Vray Lights?

[davision]

Is this a really dumb question or something? Either people aren't answering because I'm an idiot and the answer's too obvious -- or maybe it's the opposite, and the answer isn't easy -- or doesn't exist.

I feel like I know Vray fairly well, but admittedly not an expert on the massive number of Render Elements at our disposal). I would think this is something that people commonly need to do. I know I can do a custom pass with matte objects and all that -- but I was hoping for a render element that I can add to the beauty pass for simplicity/speed's sake.

[leo.surrealismo]

I think you need to create a vraylight material for that. just put the light invisible and the texture simulating the emissive light.

[davision]

I don't think that's a good option. I believe I read Vraylight Material is much slower to render than a normal Vraylight since the native light object is heavily optimized. Maybe that's outdated info, but I don't think so.

[leo.surrealismo]

in this situation, that is not the case. you are still using the light to iluminate the scene; the vraylight material is just to emulate the shape of the light so you can mask it.

[davision]

Okay, that make sense. Thanks. The issue is that as the lights are far away, and using a Vraylight for the renderable shape works just fine. I'll now have to create a bunch of planes for each lights in order to use this other method. I wish there was a way to just use the VrayLight objects as they are.

(Vlado: -- is it possible to get VrayLights to work with Obj ID in Multimatte?.... I don't mean in the current Vray version but is it 'technically' possible as a future enhancement?)

[dans]

The shape of the light shows up in the VRayObjectID render element.

Daniel

[davision]

Thanks Dan. I'll try that. Can it be anti-aliased like Multimatte? That was one of the reasons I've always been a fan of MM.....

[dans]

Thanks Dan. I'll try that. Can it be anti-aliased like Multimatte? That was one of the reasons I've always been a fan of MM.....

Yes, switch VRayObjectID output type to Color (with AA). Compared to a MultiMatte - the quality of the matte you can extract is reduced if objects appear in very similar colors of course.
You can also use psd-manager - just tested. Use the scene layer output (e.g. you may have your lights on a layer anyway) or named selection set output mode then.

It is kind of unusual for a light to appear as geometry in the render - that is why some tools behave a bit strange (like not being able to be pick it in the include/exclude list of a MultiMatte, same problem in psd-manager object output list). It is a special case that needs to be handled differently in the code.

Daniel