An Analysis of Variations in Foot Contours Based on Direction Angles

Abstract

Information on both shape and dimension of the foot is necessary for ergonomic purposes. A foot measurement system was developed to obtain this information automatically. Shape data was obtained of foot contour and instep cross section for 152 male subjects by this system. Each of the shapes of phalangeal and tarso-metatarsal parts of foot contour and instep cross section was approximated by a polygon with equidistant vertices, and represented by a sequence of angles between the edges and coordinate axis X (direction angles). Variations in these contour shapes were analyzed using principal component analysis. The results were: 1) three to five shape factors were extracted for each contour shape; 2) most of these shape factors showed very low correlations with somatometric measurements and indices; 3) variations in the shape of the three contours are independent of each other. Possible applications of the present results to shoe-last construction were discussed.