Image analysis system for acquiring three-dimensional contour of foot arch during balanced standing

Compared to the X-ray approach, footprint analysis is a non-radiation and more viable method for clinical assessment of the medial longitudinal arch of the foot. In this study, we have designed an optical footprint acquisition system that consists of a digital camera and two pieces of glass, each with four load cells under each corner. When the subject stands on the transparent force plates, the digital camera is triggered, photographing the soles of the feet at the moment when both feet bear approximately at the same weight. A blue gel is placed between the foot and the force plate to enhance the contrast between sole and background. Based on the relationship between the brightness of the image and the thickness of the gel, the three-dimensional (3D) structure of the arch can be reconstructed which can provide more representative information than a conventional footprint image, with its low resolution and easy smearing.