Optical EngineeringFractional moire fringe analysis by optimization
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A new method (algorithm and computer implementation) has been developed to define the 3-D shape of a surface based on an analysis of the shadow moiré patterns of the object. The approach is based on a phase-shifting technique enhanced by the solution of a set of overdetermined nonlinear equations involving the light intensities acquired by means of the shadow moiré method. Such an approach allows the accuracy of the measurements to be improved by utilizing excess information. Because the method uses a conventional white-light source, it can be applied to measure the geometry of human faces and bodies as well as the out-of-plane surface deformation of a loaded structure. The theory of the algorithm is described, together with test results. The results obtained show that the described approach can resolve the shape of an object with an average error of less than 2%.