Date of download: 12/16/2017 Copyright © ASME. All rights reserved. From: The Force Attenuation Provided by Hip Protectors Depends on Impact Velocity, Pelvic Size, and Soft Tissue Stiffness J Biomech Eng. 2008;130(6):061005-061005-9. doi:10.1115/1.2979867 Figure Legend: Demonstration of the steps used in determining pelvic surface geometry from the elderly participants. (a) Photograph of the participant during the experiment, showing the 10×10 grid of markers recorded by the motion capture system. (b) 3D representation of the markers in the motion capture software. (c) We aligned the frontal and sagittal midlines from each subject and defined a polar (r,θ) coordinate system having its original at the common body midpoint. For each subject we plotted best-fit splines representing the marker positions at each transverse plane. We then determined the average (r) distance from the origin to the spline surface at ten angles: reference (body midpoint to left GT), 10deg, 20deg, 30deg, 40deg, and 50deg posterior to the reference angle and 10deg, 20deg, 30deg, and 40deg anterior to the reference angle.