Citation

Aurand AM, Dufour JS, Marras WS. J. Biomech. 2017; 58: 237-240.

Affiliation

The Ohio State University, Integrated Systems Engineering, Spine Research Institute, Columbus, OH, United States. Electronic address: marras.1@osu.edu.

Copyright

(Copyright © 2017, Elsevier Publishing)

DOI

10.1016/j.jbiomech.2017.05.006

PMID

28549599

Abstract

Optical motion capture is commonly used in biomechanics to measure human kinematics. However, no studies have yet examined the accuracy of optical motion capture in a large capture volume (>100m(3)), or how accuracy varies from the center to the extreme edges of the capture volume. This study measured the dynamic 3D errors of an optical motion capture system composed of 42 OptiTrack Prime 41 cameras (capture volume of 135m(3)) by comparing the motion of a single marker to the motion reported by a ThorLabs linear motion stage. After spline interpolating the data, it was found that 97% of the capture area had error below 200μm. When the same analysis was performed using only half (21) of the cameras, 91% of the capture area was below 200μm of error. The only locations that exceeded this threshold were at the extreme edges of the capture area, and no location had a mean error exceeding 1mm. When measuring human kinematics with skin-mounted markers, uncertainty of marker placement relative to underlying skeletal features and soft tissue artifact produce errors that are orders of magnitude larger than the errors attributed to the camera system itself. Therefore, the accuracy of this OptiTrack optical motion capture system was found to be more than sufficient for measuring full-body human kinematics with skin-mounted markers in a large capture volume (>100m(3)).

Copyright © 2017 Elsevier Ltd. All rights reserved.

Language: en

Keywords

Accuracy; Gait; Marker error; Measurement error; Motion capture; Motion tracking; Optical motion capture