Polar Express (U)

The film is based on the classic children's tale by Chris Van Allsburg and is directed by one of the kings of the feel-good movie genre, Robert Zemeckis. It also features Tom Hanks in not one but five roles, including that of the eight-year-old boy at the centre of the story a possibility made real by new technology known as performance capture.

Simply put, performance capture means that an actor like Hanks can appear as anyone or anything simply by dressing in a special skin-tight bodysuit, covered in hundreds of infra-red sensors, which relay the smallest nuance of movement back to a computer which, in turn, translates it into human motion.

On-screen, it marks the next step in animation, but it could also mean, in theory, that past stars, such as Steve McQueen or Marilyn Monroe, could be revived to take on new roles or present stars, such as Hanks, could remain forever youthful.

But Hanks was keen to play down the negative implications of the process for The Polar Express.

"Peter Jackson is remaking King Kong right now with Andy Serkisr who played Gollum playing the part of King Kong," he explained.

"There's an example of what you can do with this and again the possibilities are endless, but it's always going to be defined by the story you need to tell.

"No optical way of making a movie or digitally rendering it is going to supersede the importance of what the story is."

He continued: "The fact that I played an eight-year-old kid in this film is the best example of what technology will allow. You will no longer be limited by your size, shape, skin colour or gender. None of that is going to matter. If you have the interpretation that the director wants for the role, then you can play any role. I could play Florence Nightingale or Abraham Lincoln. Meryl Streep could do the same. "And that can be very exciting for a number of actors who would never get the opportunity to play a certain role. This technology will allow that."

Adds Zemeckis: "Everyone thinks about this from a two-dimensional point of view. We're thinking about what Tom looks like. You could have someone mimicking Tom, but it won't be Tom.

"The way you've got to look at this is the other way around; it's the actor being liberated to do characters that don't necessarily exist, but not copying what another person looks like; so you'll have an image of Tom, but if some actor is there remanipulating his cyber skin, it'll never be Tom. It'll be like a tribute artist trying to be like The Beatles"

With this in mind, the technology also has another benefit in terms of the actor giving a performance, explains Hanks. "It was very liberating, in some respects, such as the pace with which we were able to work, the speed with which we could imagine these things and the freedom of not having to wait.

"I think that's why actors go nuts after a while because you have to go in and pretend to cry over something and then sit in their trailers for two and half hours before they're called in to go and cry over the same thing all over again.

"Yet, the speed with which we could do this was really like a magnificent return to a type of acting that you do on stage, more so than in films."

Hanks did, however, confess to missing costumes, as they can be an invaluable tool in helping him to get into his role.

"That was the hardest thing to get used to. I mean, without those pockets as the Conductor and without the heavy overcoat of the Hobo, and without the bathrobe and the slippers of the Little Boy, you had to remember an awful lot of stuff that was not there, but that's our job.

"That's what we do for a living. We just had to do it for a bit longer and to a further degree on The Polar Express."

The film is clearly a labour of love for Hanks and co, and everyone was determined not to let the effects overtake the story.

But having acquired the rights to Chris Van Allsburg's popular children's book, one of the conditions involved was that the story wasn't filmed using traditional animated techniques.

Explains Zemeckis: "And I didn't think it should be done as a live action movie, because all the charm and magic of the beautiful illustrations that were in the book, which I think are so much the emotion of the story, would be lost. "So we had to decide how to 'do' the movie and I basically presented the dilemma to Ken Rawlstein, at Sony Imageworks, and said how do we get these Van Allsburg paintings to move, and how do we make them moving paintings? That's where he came up with this process of doing it virtual' using motion capture."

The book in question tells the story of an eight-year-old boy whose failing belief in Santa Claus is put to the test when he is invited to ride the magical Polar Express to the North Pole on Christmas Eve.

During the course of the journey, the boy rediscovers his faith in both Father Christmas and the spirit of Christmas.

And it is this part of the message that first drew Hanks to the book, which he read repeatedly to his own children. "Christmas is what you, yourself, put into it. The Polar Express is a very elegant book, and I think grown-ups get more out of reading this to their kids than kids, because it's told from the perspective of a grown-up. The last line of the book is 'and the bell still rings for me'.

"This is powerful stuff, and it's an important aspect of our lives that even though there might be no empirical evidence for such a thing as the Christmas spirit, if you want it to be so, then it is there, and that's why I think we made the movie in the first place, in order to communicate that rather important but rather personal idea."

So is Hanks a firm believer in the Christmas spirit? "I think Christmas is a reward we give ourselves at the end of a year of one damn thing after another. It's a time of true solace and emotional replenishment," he replied.

"I think that we get something from the season and the connection that we have to our family and to the consciousness, say, for example, that really is a sincere wish for peace on earth, and I think everybody does truly feel that. "Maybe it comes out on Christmas morning, or Boxing Day, or at Midnight Mass on Christmas Eve, but I think it is a moment where, as human beings, we are all momentarily bound together in something that is larger than ourselves.

"You don't necessarily have to be spiritual to feel it and I think without it, we would all have long since exhausted ourselves off the planet."

n The Polar Express opens in cinemas on December 3.