Validating retargeted and interpolated locomotions by dynamics-based analysis

Abstract

Retargeting and interpolation methods may introduce physical inaccuracies in virtual human animation. This paper presents a method for evaluating the dynamical correctness of retargeted and interpolated motions. We determine resulting forces and torques at joints, with special attention to the ground reaction forces. With this intention, we propose an automatic creation of the biomechanical model of the character upgraded with the masses and inertias of the limbs and the motion mapping on this model. Then using support phase recognition, we compute resulting forces and torques by an inverse dynamics method.We evaluate how the retargeting and the interpolation methods change the physics of the motions by using the results of our analysis on artificial and real motions and using literature and experimental data from force plates. Our evaluation relies on the study of several retargeting and interpolation parameters such as the global size of the character, the relative ratios of limbs, the structure of the model, the length of step, the motion style and the character velocity.