With a career characterised by box office success and technological challenges, Robert Zemeckis seems a natural choice for The Polar Express. He pushed the boundaries of special effects with Who Framed Robert Rabbit?, Death Becomes Her and the Oscar-winning Forrest Gump. He also enjoyed success with the Back To The Future films, Romancing The Stone, the sci-fi tale Contact and directed Tom Hanks in Cast Away, bookending the production of What Lies Beneath as Hanks lost weight for the latter stages of his role.

Was The Polar Express always an obvious movie for you to make, with your track record in technologically innovative subjects?

No, it wasn't. But one of the conditions that author Chris Van Allsburg put on the sale of the rights to us was that he didn't want it to be an animated cartoon. At the same time I didn't think it should be done as a live action movie because all the charm of the beautiful illustrations that were in the book would be lost, and I think they are so much a part of the emotion of the story. So we had to decide how to 'do' the movie and I basically presented the dilemma to Ken Ralston at Sony Imageworks and asked how we turn these Van Allsburg paintings into moving paintings. That's where he came up with this process of doing it 'virtual' using motion capture.

Does it feel like technology has finally caught up with your imagination?

It certainly has allowed me to basically create any image that I could imagine. The movie is only limited by my imagination because I was able to do exactly that. If I said I think we should put a tree here, there it was. So it was a really fantastic experience in that regard and I think it was the most relaxed and the least compromising I've ever had to be on a movie because I could get the camera where I wanted it to be without being limited by the physical world.

How do you feel now, looking back on the film?

I have to say when I make these movies it takes me a couple of years to actually understand what I got out of the process. I couldn't answer that right now, all the pain and suffering is just too close. Knowing what the themes of the movie were that we intended to make, I know what we were trying to do. But how this has affected me as a person and as a filmmaker, I really won't know for three or four years.

There is a suggestion that the film will be pushed for Best Animation Oscar. How do you feel about that?

We're appreciative of that, although this isn't an animated film; it's digitally rendered. The acting is all acting, the directing is all directing. So I think aside from the Academy creating a new category - which I don't think they're going to do - I see no reason why it shouldn't be considered for Best Picture. That would be great.

In a way it's the antithesis of Cast Away, which saw you suspend filming to let Tom Hanks achieve a very real physical change, before resuming with his leaner form...

The thing we said to ourselves working on Cast Away was "What would he really do?", "what would really happen?", "what would really happen if this coconut didn't open?", "if he had to try and make fire?". But here it was absolutely the opposite of that. We never asked those kind of questions once.

You obviously enjoy a very productive working relationship with Tom. What do you think is the key to that?

I think we love working together because our sensibilities of what should be in the movie are very similar. In the three films that we've done there hasn't been a single situation where we didn't see eye to eye. Not one.

The Polar Express is released in the West End on Friday 3rd December 2004 and in UK cinemas nationwide on 10th December 2004.