Simulating Skin Deformation Using Anatomical Structure, Muscle Dynamics, and Soft Tissue Dynamics

1 Movement of skin and muscle is essential for bringing a character to 2 life. This movement is difficult to animate in a realistic fashion us3 ing traditional techniques because of the subtle details required. In 4 this paper, we present an algorithm that generates natural, dynamic, 5 and detailed skin deformation from standard motion capture joint 6 angle data. The algorithm consists of two steps: identification of a 7 muscle deformation model and simulation of the skin deformation. 8 In the identification step, we use a musculoskeletal model to iden9 tify muscle deformation parameters that relate the muscle shape to 10 its length and tension. The muscle shape is measured using a large 11 number of motion capture markers from a few trials. The simula12 tion step first uses the identified muscle deformation model to ob13 tain the quasi-static muscle shape at each frame of a given motion 14 sequence. The skin deformation is then computed by simulating the 15 passive muscle and soft tissue dynamics as a mass-spring-damper 16 system. We demonstrate our method using joint angle motion cap17 ture data of performances with muscle co-contraction and external 18 impacts. Experimental results show that the simulated skin defor19 mations are qualitatively similar to high-speed camera observations 20 of actual skin deformations. 21 CR Categories: I.3.7 [Computer Graphics]: Three-Dimensional 22 Graphics and Realism—Animation 23