Patches: character skinning with local deformation layer

Abstract

We present a layered geometric approach to the skinning of character animation. On top of a global shape deformation, B-spline surface patches are attached to various body parts for local control. The patches are directly manipulated so as to generate example local shapes at some important poses. During character animation, the B-spline control points move continuously by kinematically interpolating a set of example patches, and at the same time they can also move dynamically by elastic simulation. The movement of control points changes the shape of a local patch, and consequently skin vertices move according to the patch deformation, finally generating the desired local deformation. We demonstrate the effectiveness of our approach by generating natural local details at various poses including muscular effects and elastic deformation. Moreover, dealing with only a small number of control points, the proposed method is very efficient, while generating hundreds to thousands frames per second. Copyright © 2009 John Wiley & Sons, Ltd.