Reactive synthesizing of human locomotion combining nonholonomic and holonomic behaviors

The trajectories of walking humans can be divided into two major classes: first, nonholonomic trajectories during which the orientation of the human body and the one of the motion are aligned (e.g., straight walking), and second, holonomic ones during which lateral velocities are observed (e.g., side-steps). The major contribution of this work is a general locomotion synthesis method for digital actors which enables combining nonholonomic and holonomic walk behaviors. Our motion synthesis technique is based on a motion capture blending method. Such a method is able to transform a low-dimensional trajectory describing the global displacement of a digital actor into a high-dimensional motion which involves all the degrees of freedom of the digital actor body. We extend previously existing motion blending techniques [12] to reach this goal. More precisely, we consider lateral velocity as a new input of the motion synthesis problem, whereas only tangential and angular were initially considered. Thus, the digital actor locomotion is controlled from 3 inputs in our approach: the tangential velocity, the angular velocity and the lateral velocity. The paper describes the major steps of our approach. At pre-processing, we analyze some motion captured locomotion cycles to build a Motion Library. The content of the library is projected into the Control Space. Then, at runtime, input (i.e., desired walk velocities) is also projected into the Control Space. We deduce a selection of motion captured locomotion cycles from the library, which are finally interpolated to generate a locomotion animation for digital actors. The newly generated locomotion cycle exhibit the desired input velocities.