Chop It Up! Animation-Driven Modeling, Simulation, and Shading in the Kitchen

Patrick Coleman, Eric Froemling


In Disney/Pixar's Ratatouille, the creation of believable cooking environments with all their complexity has been an important element in presenting a rich world that helps draw the audience into the story. Part of that complexity arises in the preparation of food before cooking. To create complex animations of food in preparation, we designed a system that uses an animated cutting object, such as a knife, to procedurally model, simulate, deform, and prepare for shading various geometric food models as they are sliced, chopped, peeled, or otherwise broken apart. The motion of a knife (or other object) is analyzed relative to the food model to determine a sequence of cutting operations that will remodel the object as a collection of pieces. As each new piece is created, it is added to a physical simulation to generate believable response motion. We transfer surface shading parameterizations and scalar fields to resulting faces that correspond to surfaces on the original object, and we generate additional scalar fields to assist users in shading new internal surface faces. This approach to creating chopping effects entirely dependent on an animated knife allows animators to focus on character performance without needing to consider the complex modeling and motion associated with chopping.

Available as Pixar Technical Memo #07-13