Layered construction for deformable animated characters

TLDR

The paper proposes a methodology for creating and animating computer‑generated characters that integrates robotics, physically based modeling, and geometric modeling. The method uses an articulated robotics skeleton to constrain geometric deformation control points, with animator‑tailored muscle layers providing squash‑stretch behavior, and a hierarchy of composite deformations for multi‑layered local and global shape transitions that determine the final surface. The approach yields independent articulation and surface geometry, supports higher‑level motion control, offers a consistent uniform representation tunable by the animator, and a prototype system (Critter) demonstrates layered construction of deformable animated characters.

Abstract

A methodology is proposed for creating and animating computer generated characters which combines recent research advances in robotics, physically based modeling and geometric modeling. The control points of geometric modeling deformations are constrained by an underlying articulated robotics skeleton. These deformations are tailored by the animator and act as a muscle layer to provide automatic squash and stretch behavior of the surface geometry. A hierarchy of composite deformations provides the animator with a multi-layered approach to defining both local and global transition of the character's shape. The muscle deformations determine the resulting geometric surface of the character. This approach provides independent representation of articulation from surface geometry, supports higher level motion control based on various computational models, as well as a consistent, uniform character representation which can be tuned and tweaked by the animator to meet very precise expressive qualities. A prototype system (Critter) currently under development demonstrates research results towards layered construction of deformable animated characters.