The Process of Motion Capture: Dealing with the Data

Abstract

This paper presents a detailed description of the process of motion capture, whereby sensor information from a performer is transformed into an articulated, hierarchical rigid-body object. We describe the gathering of the data, the real-time construction of a virtual skeleton which a director can use for immediate feedback, and the offline processing which produces the articulated object. This offline process involves a robust statistical estimation of the size of the skeleton and an inverse kinematic optimization to produce the desired joint angle trajectories. Additionally, we discuss a variation on the inverse kinematic optimization which can be used when the standard approach does not yield satisfactory results for the special cases when joint angle consistency is desired between a group of motions. These procedures work well and have been used to produce motions for a number of commercial games.