Robert L. Cook, John Halstead, Maxwell Planck, David Ryu
May 2007
Many renderers perform poorly on scenes that contain a lot of detailed geometry. The load on the renderer can be alleviated by simplification techniques, which create less expensive representations of geometry that is small on the screen. Current simplification techniques for high-quality surface-based rendering tend to work best with element detail (i.e., detail due to the complexity of individual elements) but not as well with aggregate detail (i.e., detail due to the large number of elements). To address this latter type of detail, we introduce a stochastic technique related to some approaches used for point-based renderers. Scenes are rendered by randomly selecting a subset of the geometric elements and altering those elements statistically to preserve the overall appearance of the scene. The amount of simplification can depend on a number of factors, including screen size, motion blur, and depth of field.
Additional materials: [SiggraphSlides.pdf], [WithAndWithoutSimplification.mov]
Available in the Proceedings of Siggraph 2007.
Available as Pixar Technical Memo #06-05a
Other versions:
David Ryu, Paul Kanyuk
May 2007
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.
Available as Pixar Technical Memo #07-02
David Ryu
May 2007
Featuring plush rats, well-groomed humans, and a colony of rodents numbering a thousand strong, Ratatouille had shots where the original scene descriptions contained many hundreds of millions of hairs. To make these shots renderable, we developed many new technologies to optimize our RenderMan-based hair rendering pipeline, including caching to speed up runtime sculpting, a technique for optimizing bounding boxes for RiProcedurals, and a smooth level-of-detail system incorporating depth-of- eld and motion blur. These techniques resulted in an order of magnitude reduction in hair rendering time and memory compared to the already optimized pipeline used previously in Pixar films.
Available as Pixar Technical Memo #07-09