(CNET) -- 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."



For May, "Up" producer Jonas Rivera, director Pete Docter, and the many others involved in making the film, believability was key, even within the context of a story about a flying house. And while a major part of instilling that believability must come from a well-conceived and executed story and script, the animation is no less responsible for winning over potentially skeptical audiences.



Balloons, the mother of animation invention May said that the animation department at Pixar never even considered hand-animating the balloons. But even standard computer animation wouldn't be up to the task, because of the N-squared complexity involved in the thousands of interdependent balloons. Instead, the studio's computer whizzes figured out a way to turn the problem over to a programmed physical simulator, which, employing Newtonian physics, was able to address the animation problem.



"These are relatively simple physical equations, so you program them into the computer and therefore kind of let the computer animate things for you, using those physics," said May. "So in every frame of the animation, (the computer can) literally compute the forces acting on those balloons, (so) that they're buoyant, that their strings are attached, that wind is blowing through them. And based on those forces, we can compute how the balloon should move."



This process is known as procedural animation, and is described by an algorithm or set of equations, and is in stark contrast to what is known as key frame animation, in which the animators explicitly define the movement of an object or objects in every frame.



Procedural animation has been around for some time, but May suggested that even the most difficult uses of it in the past don't come close to what Pixar had to achieve in "Up."



Pixar fans may remember the scenes in "Cars" of a stadium full of 300,000 car "fans" cheering on a high-speed race below, each of which was independently animated. That, too, was done with procedural animation, May said, since creating so many cars individually would have been a non-starter.
What is the movie about? What company created the film "Up"? Who faced many new technological challenges? What company made the film Up? How many balloons were animated? What day does the film "Up" open on?
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. Pixar production team at Pixar Pixar more than 10,000 helium Friday.
question: What is the movie about?, answer: 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. | question: What company created the film "Up"?, answer: Pixar | question: Who faced many new technological challenges?, answer: production team at Pixar | question: What company made the film Up?, answer: Pixar | question: How many balloons were animated?, answer: more than 10,000 helium | question: What day does the film "Up" open on?, answer: Friday.