Iterative estimation of the topography measurement by fringe-projection method with divergent illumination by considering the pitch variation along the x and z directions

This paper deals with the application of the fringe-projection method for the measurement of large object surfaces. In this case, the generated fringe pattern is equivalent to that obtained by using divergent beams, i.e. the relation between phase and height is not linear. In this work, both the pitch variation in x-direction of the projected grating and the perspective problem of CMOS camera are taken into account for the formulation of a novel algorithm that iteratively retrieves the correct surface point positions. The methodology is applied to a large car component and the obtained results are compared with those obtained with a commercial scanner (Z-Scanner 700).