Expansion of 3D measurement area based on scanning mirror

Optical three-dimensional (3D) measurement methods have been widely used in many important fields due to the advantages of non-contact and high efficiency. Among these methods, fringe projection profilometry (FPP) is the most promising method because of its high accuracy. However, the 3D measurement area of FPP is reduced by the misalignment between the field of views (FOVs) of the camera and the projector. The misalignment occurs because the spatial positions of the projector and the camera are different, which is inevitable in the fringe projection system (FPS) only including a single camera. The misalignment leads to two cases: the first case is that the regions without fringes are captured by the camera, and the 3D shape of the regions cannot be restored. The second case is that the regions with fringes are not captured by the camera. In the second case, the 3D shape of the regions can be restored when the regions are captured by the camera. This paper presents a multi-view FPS (MVFPS), which consists of a camera, a projector, and a scanning mirror. The FOV of the camera can be changed by rotating the scanning mirror, which can include the regions in the second case in the camera's FOV. First, multiple rotation angles of scanning mirrors are preset in advance, and the internal and external parameters of the projector and camera corresponding to each angle are calibrated. Then, a set of fringe patterns are projected for reconstructing the 3D shape at each angle. Finally, all 3D shapes obtained at different angles are combined as a whole 3D measurement result by the point cloud registration algorithm. Experiments show the proposed MVFPS, and the 3D measurement area of a plaster statue is expanded after combining the multiple 3D shapes at different angles of the scanning mirror.