Accuracy of three-dimensional linear and angular estimates obtained with the Ariel Performance Analysis System

ABSTRACT. Klein P J, DeHaven JJ. Accuracy of three-dimensional linear and angular estimates obtained with the ariel performance analysis system. Arch Phys Med Rehabil 1995;76:183-9. • Computer-assisted video motion analysis is a method of evaluating human kinematics that offers promise both for research and for clinical application. This study detel'mined the upper limits of accuracy and consistency of linear and angular measures obtained using the Ariel Performance Analysis System. Reference standards included a meter stick and a universal 360 o goniometer. Average mean error observed for reconstruction of absolute point estimates was found to be less than 3.5mm. Mean error estimate for three-dimensional (3D) reconstruction of a linear standard was found to be 1.4mm (SD 0.30). Average mean angular error observed for 3D reconstruction of goniometer settings 10 ° to 170 ° was found to be 0.26 ° (mean SD 0.21). System users are cautioned that some increased error associated with software derivation of joint angles exists as angles approach 180 °, use of wide-angle lens accessories introduces a systematic field-dependent bias; and planar rotation introduces some (<2 °) random error. © 1995 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Computer-assisted motion analysis is a method of evaluat