How technology lifts Pixar's 'Up'

If you want to consider a difficult computational problem, try thinking of the algorithms required to animate more than 10,000 helium balloons, each with its own string, but each also interdependent on the rest, which are collectively hoisting aloft a small house.The production team at Pixar faced many new technological challenges on "Up," its tenth feature film.

That was the challenge the production team at Pixar faced when it set out to begin work on "Up," its tenth feature film, five years in the works, which hits theaters on Friday.

There was absolutely no way the team was going to hand-animate the balloons. Not with their numbers in five-figures, and especially not when you consider that within the cluster, every interaction between two balloons has a ripple effect: If one bumped another, the second would move, likely bumping a third, and so on. And every bit of this would need to be seen on screen.

In "Up," the story revolves around the main character, 78-year-old Carl Fredricksen, who, frustrated with his mundane life, ties the thousands of balloons to his house and sets off for adventures in South America. A small boy ends up marooned on board, and hilarity ensues.

The cluster of balloons is so central to the film's branding--it's called "Up," after all--that to promote the film, Pixar teamed up with two of the world's cluster ballooning experts for a nationwide tour involving a real-life flying armchair and dozens of huge, colorful balloons.

"You have a movie that's about a house that flies, which is a pretty far-fetched idea," said Steve May, the supervising technical director on "Up." "We all know, from kids' parties, how a bunch of balloons behave, so if we could animate balloons in a realistic way, the believability that the house could fly would sell"