Calibration of a system of projection moire for relief measuring: biomechanical applications

The projection moire method which belongs to the family of structured light projection allows to obtain the relief of an object or the out-of-plane displacements by the difference in relief between two prompting states. Its principle consists in projecting a sinusoidal grating of vertical lines onto the surface of the object, and the relief is then deduced from the geometric parameters of the set-up and the analysis of the grating observed by a numeric camera. Several implementations are possible, some of them allowing simplifying assumptions for the calculation of the relief. This paper presents this measurement method in any case. A calibration process has been developed to determine the necessary geometric parameters influencing the calculation of the relief. (C) 2003 Elsevier Science Ltd. All rights reserved.