I was just watching the Polar Express and I really just took notice of how well the animation was done for this movie. I decided to research how they made the animation in this movie look so life like, yet still cartoonish. I'm sure that there are many people who already know what they did to do this, but I personally do not.
After I browsed around for a bit I found that they used a process called "action capture" which was new for it's time in 2004, and they basically digitized the movements of the actual people that were in the cast. So basically they acted out the movie and scenery and costumes were added later, which is a pretty awesome concept. More recently they are also using this technology for the movie Tintin too. Overall I think this movie is amazing, but I am kind of biased because I am a sucker for Christmas! However, there is no argument that this movie has amazing animation technology and is now a true holiday favorite.
http://abcnews.go.com/Entertainment/JoelSiegel/story?id=245769#.TuIWCmMk67s <-my info