Motion analysis is an important tool for biomechanical studies and its accuracy and reliability for large-volume applications, such as gait labs, is well-established. Previous work has offered a comparison of commercially available systems.[1] No work to date has quantified the error in position of a given tracking marker caused by its removal from the view of one or more cameras, either by obstruction or by the data being removed during the image reconstruction process. This issue is critical to the tracking of extremely fine movements such as the travel of the radial head on the capitellum during elbow motion. Due to anatomical constraints, markers must frequently be placed a distance away from the body of interest and must be smaller than those conventionally used in gross motion analysis. The nature of the motion may not permit all cameras to view all markers all of the time. For example, a specimen may itself obstruct a camera’s view during certain motions.
