Morphology-independent representation of motions for interactive human-like animation

This paper addresses the problem of human motion encoding for real-time animation in interactive environments. Classically, a motion is stored as a sequence of body postures encoded as a set of joint rotations (quaternions, Euler-like angles or rotation matrices). As a consequence, Cartesian constraints must be solved using inverse kinematics and/or optimization. Those processes involve computation costs that do not allow real-time animation of several characters in interactive environments. To solve such a problem with a minimum computation time, we designed a motion representation independent from the morphology and containing the constraints intrinsically linked to the motion such as feet contacts with the ground. With such a description, a unique motion can be shared by several characters with different morphologies and in different environments. We also adapted a Cyclic Coordinate Descent algorithm that takes advantages of this representation in order to rapidly deal with complex tunable spacetime constraints. For example, this method enables to interactively control at least eight characters with different morphologies that interact each other during a fight training. Hence, each character has to deal with geometric constraints that can change at every time, depending on the opponents’ morphology and gestures.