That's a nice-looking virtual set. Two questions:
1) I see that the layer labeled People is a Targa sequence. No video camera shoots Targa sequences. Why not import the original green screen footage, then use Keylight to pull the chroma key and create transparency around the talent? You can animate garbage masks around the people if necessary.
2) Were there really chairs in front of the male talent when you shot the green screen?
2) A very expensive camera. Just kidding, the people are a series of IFL images that were imported into 3dsmax and rendered out as a series of exr's. I like working with exr format more than any other because of how they handle gamma.
3) There were no chairs in front of the talent. That scene is completely CG. that was generated from 3ds max and mental ray.
What I am doing here is trying to set up an efficient workflow that uses after efects to insert real footage of people rather than CG people. I used to use autodesk combustion/toxik to composite stuff like this but I think that after affects is better suited for it. Toxik is great for compositing the CG scene but not for after affects.
Anyhow, I believe I have founf the answer. I put the talent into another comp layer and and put the set matte on the comp layer instead of the talent layer. Here is another screen shot. I am sure there are other ways to accomplish this. If there is I would love to know.
FYI, this is a 10 second clip from the animation 300 frames. The reason for this workflow is so I can stay efficient with architectural changes and not have to worry about the after effects to be rendered everytime.
Using the Set Matte effect is one way to do it, but I think a better-looking workflow would be to use a chroma key effect like Keylight on the talent footage. You have better control over the edges of the subjects. You can precomp the chroma key shot if you like.
I presume you'll have access to talent footage properly lit & shot for chroma key, using a camera that shoots & records video of sufficient color resolution for chroma key.
I also presume you're knowledgeable of the considerations to be taken when shooting and working with virtual sets.
I am not sure how to keylight footage. Would you mind explaing that workflow with me?
You apply Keylight to a layer just like you apply any other effect. Using Keylight can be a bit tricky, and you can't do it intuitively.
Fortunately, there are resources you can call on. Look at this page. Find the section labeled "Keying Effects Including Keylight", about halfway down. It contains links to tutorials on using the effect. Actually, the entire page is extremely valuable if you're new to chroma keying. Newcomers usually aren't aware of what it takes to make the process successful.
You'll also find Keylight tutorials on the Creative COW, not to mention the tutorial on The Foundry website; they developed Keylight.