From CNET: 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.
That was the challenge the production team at Pixar faced when it set out to begin work onUp,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. [continue]