3D reconstruction and positioning of surface features based on a monocular camera and geometric constraints

This paper proposes a 3D reconstruction and positioning method based on a single detecting camera and geometric constraint to evaluate the defect quantitatively. We realize the camera orientation through datum point coordinates acquired by a photogrammetry system and then solve the equation of the defect detection camera model and surface constraints to reconstruct the color point cloud in 3D space. To realize the reconstruction and orientation of defects on objects without marker points, the system is operated by a repetitive moving of robotic arms. Finally, the experiment achieves the reconstruction of three types of products with marker points and one of the same types of objects without marks. The experiment shows that this method can limit the accuracy of surface feature positioning to 0.7 mm, and relative accuracy of the area calculation to 0.125%.