Tom Hanks has been reading The Polar Express to his kids since it was first published in 1985. After years of entrancing them with Chris Van Allsburg's fable about a boy who takes a magical train to the North Pole in search of Santa, he and his friend, Forrest Gump director Robert Zemeckis, decided to make it into a movie. The problem was how to stay true to the book's spirit and oil painting illustrations.

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Live action just wouldn't do for such a rich fantasia, so they opted for creating an animated film utilizing "Performance Capture,"a revolutionary system that uses a battery of digital cameras to film actors from 360 degrees. Zemeckis could shoot his stars and give the footage to a team of computer illustrators who built the film around the actors with the sets, props and painterly colors already scanned into their computers.

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Watching Polar Express is like stepping into the world Van Allsburg saw in his head, a mixture of Norman Rockwell charm and Rene Magritte surrealism. The characters - many played by Hanks himself, abetted by Nona Gaye and old Bosom Buddies cohort Peter Scolari - have cheeks that glow like fireplace goals. Zemeckis also highlights the surreal touches to this Yuletide yarn. The train dips and skids through an ultra vivid Arctic of icy lakes and caribou herds, while Santa's toy factory rivals that of Willy Wonka for larger-than-life thrills.

[Behold Santa's elves prepare the boy and his friends for their descent onto the North Pole.]

Riding this train is all about believing in jolly old St. Nick, but at the New York press conference, Hanks wasn't taking Christmas too seriously, quipping of holiday films, "It's just not December without All Quiet on the Western Front."The two-time Oscar winner and director Zemeckis discussed how they fell under the Express' spell, and why Performance Capture could let Meryl Streep play a Mongol emperor.

What was it that interested you about the story?

Tom Hanks: It's an elegant but sophisticated story about what Christmas means to everyone, and I got a very tactile feeling from reading the book. There's something stunning about Chris Van Allsburg's paintings. They're impressionistic versions of this child's house and what it was like to be on a train.

[Go behind the scenes of the making of the movie with Tom Hanks and director Robert Zemeckis.]

How do you turn that into a movie?

Hanks: When Bob and I first started talking about it, it was really only from the perspective of, "Well, what do you think? Is something possible or here or not?"The idea of turning it into a movie was a complete X factor. We had no idea if it's going to be possible or not.

Could you have made it in live action?

Robert Zemeckis: One of the first things I said to Tom was "I don't think this would make a very good live action movie."1) It would be impossible. Well, nothing's impossible, but it would have cost billions of dollars. 2) You would be throwing away the essence of the book, which were those paintings. The paintings are where the emotion comes from, and without those paintings, you're throwing half the book away.

What was Chris Van Allsburg's role in the film?

Zemeckis: Chris never wanted this to be an animated movie, because you couldn't make those paintings look like that in a cartoon. So we wanted to make sure that the movie's style had the same resonance as his paintings did. When we showed him our conceptual art, he couldn't be more thrilled. Sony had him come down and actually do some seminars with their artists. They could actually get some insight into what he was doing as an artist to help them to render the movie as best we could to make it look like his original art.

[Gasp as the boy and the conductor try to stop the train from skidding over a vast ice lake.]

How did making this film differ from making Who Framed Roger Rabbit?

Zemeckis: Roger Rabbit was an insane endeavor. Roger Rabbit had a team of animators that had to be directed for two years after we finished doing a live action film noir movie. This in comparison was an absolute dream, because you got to direct in two phases. You got to work exclusively with the cast, and then when we were done with that, you did the cinema part in the comfort of an office. You didn't have to worry about the elements - the rain, whether the trucks were going to get stuck in the mud, whether the generators were going to run out of gas. You didn't have any of those problems. It was wonderful!

There have been a lot of news stories emphasizing how risky it is to release a totally CGI movie.

Zemeckis: They talk about it like it's some manufactured hardware product. What those stories leave out is the screenplay. What's great about doing movies in Performance Capture is you spend only 20 percent of your budget and then you know what you've got before you spend the other 80 percent. If you make a live action [film] you send a director and a bunch of actors off and they spend 80 percent of the money, come back and [ask themselves] "Do we have a movie here or not?"

Hanks: Every one of these movies is an incredible risk. Through history people were saying, "You're going to make a movie about a big monkey with this little clay figure, one shot at a time? No one's going to care about that."And the movie's King Kong. Is The Polar Express a big risk? Yeah, of course. We could lose our shirts and people could lose our jobs if the movie stinks. But that would be the same if it was a story about me and Nona Gaye driving in a car talking to one another. If that movie stinks, we'd be in just as much trouble.

What do you get out of seeing your likeness realized in CGI?

Hanks: The Polar Express really is me as opposed to some rendering of a character that I'm supposed to be. In the Toy Story movies, it's a little puppet. It sort of looks like me, but if he was really like me, his head would be like nine feet tall!

[Watch the passengers on board the magical train get served some musical refreshment.]

Will it render actors obsolete or extend your life?

Hanks: It frees us up to a huge degree. It's possible now to play any character in any circumstance in a way that simply was not feasible before. If Meryl Streep can play the greatest Genghis Khan in history, better than anybody else, Meryl Streep can play Genghis Khan. If James Earl Jones can play the greatest Mickey Rooney in The Mickey Rooney Story, James Earl Jones can now play Mickey Rooney. There's an opportunity for actors to no longer be limited by size, weight, color of hair, gender or race.

What challenges did it pose you as an actor?

Hanks: It's actually a return to a type of acting that films do not allow you to do. It was like rehearsing a play in the round. You don't have to worry about lights, angles, rails, cameras, [or] over the shoulders coverage. We essentially did a great series of 10 or 15 minute plays in real time and we were done - Bob had everything that he needed to. So as far as being an actor goes, it was a blast.

Is there a message about the lost innocence that children had in the '50s in the film?

Hanks: It's about belief. Everybody carries around their belief with them on their sleeve. It's a very personal thing. When Bob began writing the screenplay this idea that he had was to start the movie with the first line of the book and end the movie the last line of the book. In a lot of ways I think that we just kept figuring out almost what not to do with the story as opposed what to do.

What role does Santa Claus play in your life?

Hanks: [jokingly] I actually subscribe to the more Russian tradition of a guy named Bosmorose, who would come around and he would leave you a pear if you were a good boy and he would leave you a switch if you were a bad boy. I had my share of pairs.

Do you retain a special Christmas memory?

Hanks: I always took the Greyhound bus from Oakland, California to Red Bluff to go to my mom's house. We'd get out of school we'd go down to the Greyhound bus station and get on the bus for three and a half to five hours depending on if we were transferring through Sacramento or not. I'd have a little stack of comic books and look forward to hopefully staying awake by the time we pulled into the frigid cold of Red Bluff. Hopefully, I'd be sat next to some nice old lady passing out banana bread - it happened quite often.

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