So I attended a talk by Bert Poole - He's currently serving as a CG Supervisor on their new movie "The Croods" scheduled for release in March 2013. His most recent movie, you all know of is How to Train Your Dragon, where he was also a CG Supervisor. If you don't know what that means, that means he worked on lighting C: What I'm putting below is from notes I took during his lecture.
His job is to take the directors vision and make the movie look like it. He's making compositions and helping the story to better read. If you've ever talked to me on DA for three or more posts, you might have heard me blab about my major and what I'd like to do.