Fringe projection profilometry (FPP) based point clouds fusion for the binocular and monocular structured light systems

With the advantages of high precision, strong robustness and dense point clouds (PC), the fringe projection profilometry based binocular structured light technology is widely used in surface defect detection and profile extraction. However, the binocular structured light system (BSLS) often exits the abnormal regions where is coded or encoded ineffectively suffered from the imaging orientation or surface reflectivity of measured object. It will result in poor stereo matching, and the reconstructed data is missing. To improve this phenomenon, a PC fusion method is proposed in this paper. The PC of abnormal regions in the BSLS are fused by the monocular structured light system (MSLS). Two-step method including least squares and iterative closest point is used to get the rigid transformation matrix (RTM) between the BSLS and MSLSs. The strategies of fringe modulation constraint and phase consistency constraint are performed to obtain the reconstruction regions of left and right MSLSs. The feasibility of proposed method is verified both in the theory and experiment analysis. The proposed method improves the integrity of PC in the BSLS without additional equipment, which is attractable.