coming out from the shadows

[Vormav]

I'd say it's about time for me to stop lurking. I found CGTalk to be somewhat limited when it comes to compositing, and so here I am.
I'm more of a 3D designer, but am still very interested in compositing; you guys do some amazing work with compositing.

Not to make this completely a 'new guy' post though, I do have a bit of a newbieish question for you all. It's concerning the Framestore CFC Playstation ads posted on CGNetworks recently ( http://www.cgnetworks.com/cgfilms/cgfilm.php?story_id=2606 ).
Granted I'm very new to the world of video compositing, I still know a lot of the basics of how the compositing side of things works (or at least that's what I like to think). But when it comes to something like this - the 'crowd' in these commercials - I'm stumped. No clue how it would be done, if it's purely compositing.
Anyone mind describing a bit to a newbie on how an effect like that would be achieved?

[Hugh]

I'd suspect they'd use their own in-house crowd-sim software...

I believe they developed their own tools for use on Troy (didn't we all?) which give them AI controlled crowds... The close 'hero' people would be live-action, but it would be clever lighting/rendering/compositing that would mean you can't tell the difference between the real people and the CG ones..

[LFGabel]

I guess there's many ways to do this, but I got the impression from the article that they shot many different variations of the same people, possibly with strategic greenscreen (or lots of roto work).

[Vormav]

I was given the impression from the article that there was no greenscreen, which is part of what gets me. Doesn't seem like that much roto work would really seem practical.
Of course, I also got the impression that they weren't CG. But maybe the article is just leaving off a lot of the process.

[LFGabel]

For big crowd shots (the long shots), would really precise roto work really be necessary? If I were doing it I'd make sure the heads were spot on, and not worry too much about arms. I mean the crowds just need to look like they belong there... (LOL I'm such a newb... :) How can you tell I've never worked on a shot like this?)