Shape Measurement Using CAD-Based Stereo-DIC

The aim of this study is to measure the (complex) shape of an object by using a priori information given by its CAD representation in a 3D-DIC framework. In order to follow a 3D object during its deformation and to determine 3D surface displacement fields, a first measurement of the object shape is necessary. The main goal of the present method is to obtain a CAD representation of this measurement by updating the CAD reference via a global approach to 3D-DIC. Although in the majority of the shape measurement methods a cloud of points is obtained and subsequently interpolated to create a continuous description of the surface, CAD-based stereoDIC is devised to directly measure a 3D shape described by NURBS. This approach allows a direct link to be established between the theoretical CAD model and its true geometry thereby yielding the metrology of the measured surface in the CAD language.