Seperating trees into separate pass (shadows? Reflections?)

[Parker1]

I have a very large, high poly, scene which contains a bunch of instanced proxy trees all over the place. The issue is that with the proxies turned on the scene crashes every computer on our farm. I am running out high resolution stills at around 4500 pixels (X). With the proxies off I can render the scene with no problems.

How can I separate the trees such that I can render the scene and have them reflect in the glass etc...but not show up anywhere else. Then How do I run out a separate pass of just the trees so I can comp them back in and still have their appropriate shadows being cast??? Is this too much to ask Vray to do?

Thanks everyone...

[RErender]

First, have you tried rendering to a vrimg? make sure to disable the Max vfb.

If that still won't render

Create matte objects out of the window walls, leaving the reflective glass material intact but with a -1 alpha. Then when comping the tree layer duplicate it and invert the alpha, giving you a layer with just the reflections to add to the base.