Estimation of 3-D foot parameters using hand-held RGB-D camera

Most people choose shoes mainly based on their foot sizes. However, a foot size only reflects the foot length which does not consider the foot width. Therefore, some people use both width and length of their feet to select shoes, but those two parameters cannot fully characterize the 3-D shape of a foot and are certainly not enough for selecting a pair of comfortable shoes. In general, the ball-girth is also required for shoe selection in addition to the width and the length of a foot. In this paper, we propose a foot measurement system which consists of a low cost Intel Creative Senz3D RGB-D camera, an A4-size reference pattern, and a desktop computer. The reference pattern is used to provide videorate camera pose estimation. Therefore, the acquired 3-D data can be converted into a common reference coordinate system to form a set of complete foot surface data. Also, we proposed a markerless ball-girth estimation method which uses the lengthes of two toes gaps to infer the joint locations of the big/little toes and the metatarsals. Results from real experiments show that the proposed method is accurate enough to provide three major foot parameters for shoe selection.