Three-dimensional deformation measuring system based on vision method

In order to realize automatic vision measurement for surface deformation, a three-dimensional surface deformation measuring system is proposed based on digital image correlation and binocular stereovision, and its applied key technologies such as camera calibration, correlation matching, three-dimensional displacement and strain reconstruction are deeply investigated. First, according to distortion errors of digital camera, a self-calibration method with 10-parameters model is elaborated. And a rapid image correlation algorithm based the relation of stereovision epipolar geometry is presented to improve the efficiency of the image matching. Then based on these technologies, a method for displacement and strain reconstruction is discussed. Calibration experimental results show that the precision of the camera calibration is better than 0.07 pixels. Metal tensile test demonstrates that the precision of strain measurement is very close to strain extensometer, so the system can satisfy the requirements of non-contact, higher precision and three-dimensional deformation field measurement.