a bTime c Figure 1: Hierarchical motion brushes are a powerful tool for creating stylized animated content such as the fire of this example. The user painted a set of motion brushes (a) and uses them in a scene containing two hands (b). By only painting one stroke, a complex fire effect is created that erupts from one hand and reaches the other over time (c).
AbstractOur work on "motion brushes" provides a new workflow for the creation and reuse of 3D animation with a focus on stylized movement and depiction. Conceptually, motion brushes expand existing brush models by incorporating hierarchies of 3D animated content including geometry, appearance information, and motion data as core brush primitives that are instantiated using a painting interface. Because motion brushes can encompass all the richness of detail and movement offered by animation software, they accommodate complex, varied effects that are not easily created by other means. To support reuse and provide an effective means for managing complexity, we propose a hierarchical representation that allows simple brushes to be combined into more complex ones. Our system provides stroke-based control over motion-brush parameters, including tools to effectively manage the temporal nature of the motion brush instances. We demonstrate the flexibility and richness of our system with motion brushes for splashing rain, footsteps appearing in the snow, and stylized visual effects.