Rivers of Rodents: An Animation-Centric Crowds Pipeline for Ratatouille

David Ryu, Paul Kanyuk


One of the major technical challenges in the animated film Ratatouille was creating a believable rat colony. In numbers as high as a thousand, these rats participated in highly complex and coordinated behaviors ranging from chaotic swarming to gourmet cooking. Often, the colony was the featured foreground element in the shot and thus subject to the strict motion standards of our hand- animated characters. We needed a crowds animation pipeline that had the flexibility to tackle a wide variety of complex behaviors, while also delivering motion that could pass muster alongside hero animation. We chose Massive Software's Massive Prime as our simulation engine. To ensure animation quality, our Massive pipeline preserved all the nuances of the input animation and allowed the animators to easily change the simulations, while still enabling TDs to use proceduralism to create complex behaviors. To this end we deployed a number of techniques including a system for baking our deformer based character rigs into point weights for Massive, motion retargeting tools for animation cycles, and procedural methods for swarming, leaping, carrying, and climbing, among others.

Paper (PDF)

Available as Pixar Technical Memo #07-02