Occlusion just for contact shadows of character

[sharktacos]

Here's our situation: We are rendering out in two phases
1) the static environment
2) the animated props and characters. Here we use wrapper materials applied to all the environment in order to be able to get propercast shadows from the character onto the ground.\

We then comp animated props and characters over the static environment. Yay.

The problem is the occlusion. What we need is just the occlusion contribution from the animated props and characters so this can be added to the occlusion from the the static environment. Is there a way to do this with Vray? I tried checking "ignore self occlusion" in the dirtMtl but this did not seem to work.

thanks!

[Neilg]

dirt in a light material on the ground plane/contact objects, exclude everything but the animated objects, white light material on everything else.

[sharktacos]

Thanks CG,
Every object in the static environment is a potential contact object so I can't use any white shaders (except the sky)
I think I got it working now using (a) exclusion sets for the AO for the static objects along with the (b) "ignore self occlusion" so those objects don't cast AO on (a) each other or (b) themselves, and only the animated ones cast AO.

It's a pretty unintuative workflow however, so I just wanted to confirm that there wasn't an easier way to accomplish this.

[Neilg]

It's still the same method - you exclude everything but the animated objects and only apply it to static objects

[konstantin_chaos]

You can render the occlusion during your second phase in a separate render element:
1. Add a V-Ray "Extra Tex" render element and use V-Ray dirt in the texture slot.
2. Create a (Maya)"Set" with all the moving/animated objects in it.
3. Connect the "used by" output of the set to the "result Affect" input of the V-Ray dirt (you can do it in hypershade).
4. Render
This will create an additional render element with only the occlusion contribution that you need.
It will be rendered together with the beauty pass and you don't have to change any materials.