For director John Lasseter, A BUG’S LIFE was a production filled with technical challenges. Just by setting the piece in a completely organic world meant that the combined forces of Pixar studios would have to come up with believable computer simulations for earth, wind, rain, and fire. On top of that, Lasseter wanted crowds of ants – over 700 in many shots – who would appear to be acting out their own thought processes, rather than behaving merely as mindless automatons. Achieving this effect without resorting to hand-animation proved to be difficult. “We had to find a middle ground," explained technical director Bill Reeves, “where we could take data from an animator and use that to drive the simulator, which would in turn propagate the animation in various ways to ants of all shapes and sizes, and give them different timings. We needed to scatter nuances throughout the crowd, to get the feeling that they're all reacting in their own little way."
“Every big crowd animation scene I've ever seen is groups of very limited cycles that repeated themselves," said Dale McBeath, the supervising crowd animator on A BUG'S LIFE. “Our goal was to get the crowd to act as a character, yet make each individual in the crowd appear to be fairly unique. How we did that was to fully animate an ant doing a specific behavior, just as if it was a hero character. We started with eight different characters, and broke their movements into small pieces, and through software developed by Michael Fong, we combined these movements in random ways, so there are no cycles that are repeated. That allowed each character in the crowd to be fully animated.”
Fong, Pixar‘s technical director for the numerous crowd scenes, noted that although they started with eight base models, there were additional controls to vary the ants in the crowd. “We have controls to make each ant in a crowd smaller or larger,” said Fong, “and on top of that, we have shader controls that change the colors of each model. That allowed us to add an infinite variety to their movements.
[…]
