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Adaptive Dynamics of Articulated Bodies Stephane Redon∗ Nico Galoppo† Ming C. Lin‡ Department of Computer Science University of North Carolina at Chapel Hill Figure 1: Adaptive dynamics of articulated characters. In this complex scene, 200 human characters, represented by 17,800 rigid bodies and 19,000 degrees of freedom, are suddenly pushed away from the camera due to applied forces. Our adaptive dynamics algorithm allows an animator to progressively reduce the number of simulated joints in the characters as their distance to the camera increases, while automatically determining which joints should be animated to best approximate the characters motion. Depending on the total amount of simplification specified by the animator, a potentially significant speed-up can be achieved over typical linear-time forward dynamics algorithms. Abstract: Forward dynamics is central to physically-based sim- rithms [Bae and Haug 1987; Brandl et al. 1986; Featherstone 1987; ulation and control of articulated bodies. We present an adaptive Hollerbach 1980; McMillan and Orin 1995] have a linear-time de- algorithm for computing forward dynamics of articulated bodies: pendence on the number of degrees of freedom. For a complex using novel motion error metrics, our algorithm can automatically scene with many articulated figures or with many degrees of free- simplify the dynamics of a multi-body system, based on the desired dom, however, dynamic simulation of the entire multi-body system number of degrees of freedom and the location of external forces can become extremely costly. and active joint forces. We demonstrate this method in p