"Superficial" reflection pass.

[Pixelcon]

Hi,

Here at the office we do plenty of PS work and comping in people is always quite a task especially when they need to appear behind glass. One way to do it is to overlay a reflection pass back over the 2D people, but with a reflection pass (and even with a rawreflection pass) you also get the reflection of objects that occur behind glass. This gives crappy results and can require extra render passes.

Some of my colleagues use lightwave and somehow their renderer only gives them a sort of "superficial" reflection pass where the first layer of reflection is output allowing them to simplify this task immensely. Of course this is useless if you're trying to do any proper compositional work, but for PS heavy work this would be a dream.

I didn't want to put this in the wishlist area because I'd hoped someone might have an idea on how to do this with vray in it's current state.

Any ideas? I'm trying to avoid doing extra render passes (glass as fully reflective for example gives undesirable results).

Cheers,
James

[rivoli]

does it work if, for the glass mat, you leave colour only as affecting channels in the refract tab? in that way reflections behind glass may not be considered in the reflection element.

[Pixelcon]

Yes that works! But of course the multimattes won't work properly

[rivoli]

yes, I see it's definitely not ideal. I thought other elements will be affected, so I guess it doesn't work unless you render more than one render pass..

[tricky]

Use 3D people? They always look great

We generally do a mirror glass pass and that gives a lot of flexibility. You lose some of the subtleties of 'in-scene' glass, but sometimes, it will do.