Realistic skin movement for character animation

Skin movement modeling is a crucial element for realistic animation of both human and creature characters. In this paper, we are primarily concerned with a special skin movement effect, skin sliding. Although physical properties, such as skin elasticity, are usually regarded important in physical simulation, it often leads to an increasing computational load. A complete physical solution will also limit the animator´s ability to fine-tune the visual effects. In this paper we present a physically based skin sliding modeling method borrowing an idea from structural mechanics called bar networks. The advantage of using a bar network system in simulating the physical properties of skin surfaces is that only a set of sparse linear equations need to be solved, making the method much faster than a simulation based technique. As only one additional step is added to the animation pipeline to restore the skin elastic property, this algorithm is compatible with all existing skin deformation method such as smooth skinning, muscle base skin deformation, cluster and Free Form Deformations, and it therefore does not disturb the existing production pipeline.