Scheimpflug Camera-Based Stereo-Digital Image Correlation for Full-Field 3D Deformation Measurement

To further extend the scope of stereo-digital image correlation (stereo-DIC) to more challenging environments, a novel Scheimpflug camera-based stereo-DIC is developed for full-field 3D deformation measurement, wherein the Scheimpflug condition, consisting of tilting the sensor plane with respect to the lens plane for the sake of larger depth of field (DOF) of the camera, is employed. The geometric imaging model of the Scheimpflug camera is described, on the basis of which a robust and effective stepwise calibration strategy is performed to calculate the intrinsic and extrinsic parameters of the stereo Scheimpflug rig. With the aid of a specially tailored stereo triangulation method and well-developed subset-based DIC algorithms, the three-dimensional shape and displacement of the specimen can be retrieved. Finally, practical experiments, including rigid motion tests and three-point bending tests, demonstrate the effectiveness and accuracy of the proposed approach.