The Accuracy and Precision of a Video-Based Motion Analysis System

Motion Analysis Corporation is a manufacturer of videoâ€"based motion analysis equipment. The principal products of the Corporation are video processors and software to manipulate the raw data recovered by the video processors. Although these products represent the state-of-the-art in automated video-based tracking systems, relatively little is known about the performance of such systems. The present investigation establishes precise definitions for system accuracy, system precision, and "overall system performance". Both system precision and system accuracy depend heavily on the type of hardware used to produce and acquire the raw images; however, system precision is shown to be significantly better than system accuracy, and overall system performance appears to be similar to that rendered by traditional, film-based systems. Careful selection of image acquisition hardware, together with analytical corrections for systematic error can clearly improve overall system performance. Additional investigations are underway to determine the impact of alternative scaling techniques and analytical corrections for optical distortion. Preliminary results have show that affine scaling can improve system accuracy by 2-6X.