I don't make films that are easy to market, unfortunately. I think that 'Pi' was the easiest one, because we had that symbol to stick up everywhere, so that was a good gimmick, and created a good mystery, and we didn't have to do huge scale.

CGI means, just to be clear, creating any type of image with a computer. Basically, starting off with nothing, or with images and manipulating them. The way we did it, everything was actual photographed images. A lot of that stuff was shot through a microscope of chemical reactions, yeast growing, lots of weird things, by Peter Parks. We put it into a computer and collaged it, manipulated it. Meaning we digitally shaped it to fit with other images. But there was no computer-generated imagery at all.

I wasn't a big fan of social anthropology. And, luckily, that created room for me to work in visual arts because I sort of ignored my requirements. I think I was attracted to social anthropology because I liked to travel and was always interested in far-off places.

You hear stories about directors using manipulation to get actors to do certain things, but I think when you're working with professional actors, it's all about trust. They can do anything you want, it's just a matter of them understanding what you're looking for, and the reason why.

I've been joking that if Madonna taught us anything, you've got to reinvent yourself. I think it's important as a filmmaker, as any person working in the arts, that you've got to try new stuff and challenge yourself and take chances. I've tried to take a chance with every film I've done - I've never done it the easy way, and I think that's because that's what excites me, is making as big a mountain as I can in front of me, and just trying to mount it.

When people think about the ark, they're always thinking about all the thousands of years of religious iconography of a ship with a bow and a deck, where Noah and the giraffes could walk around. In the actual written text it is basically described as a long, rectangular box.

Now there is so much expertise and brainpower it's hard to be at the cutting edge of what's cool and not do something that's totally geeky.