Effective Toon-Style Rendering Control Using Scalar Fields

Alex Harvill


An illustration of Gusteau comes to life and introduces a new facet of the film Ratatouille. To do this, a technique was needed to convert an animated 3D character into a 2D illustration. Existing renderman shaders based on normal and depth maps were difficult to control. Post processing per gprim id information robustly captures object outlines and has been previously extended with texture maps to feature some surface details. However, texture maps introduce artifacts that are quite objectionable during post processing. The id based approach is extended using scalar fields to produce well-behaved 2D edge/contour lines from 3D models. Specifically, mesh face ids and per-vertex line weights were rendered and processed to create lines and specify line thickness, respectively. This new method is fast, looks good, and is easy to control.

Available as Pixar Technical Memo #07-08