Three-Point Marking Method to Overcome External Parameter Disturbance in Stereo-DIC Based on Camera Pose Self-Estimation

Stereo digital image correlation (stereo-DIC) requires the stereo-camera system to remain fixed during the measurement process. This requirement brings a lot of inconvenience to the practical application of stereo-DIC. In many application scenarios such as dynamic measurement, the external parameters of the camera are almost inevitably disturbed, which will bring great errors to the DIC measurement results. To overcome this problem, this paper proposes a three-point marking method to determine the world coordinate system and a camera pose self-estimation method based on speckle patterns. The three-point marking method can use three undeformed feature points in the field of view (FOV) to determine the world coordinate system. The proposed camera pose self-estimation method can calculate the pose parameters of the binocular camera at the shooting time of each frame of image. This method does not require plane assumptions and has good applicability. Simulations and experiments were carried out to verify the effectiveness of the proposed scheme in overcoming external parameter disturbances.