A telecentric-perspective heterogeneous stereo vision system and its calibration

The telecentric lens is highly efficacious for precise and detailed measurements, yet typical telecentric stereo vision systems face a significant challenge due to the limited overlapping Depth Of Field (DOF) between their two telecentric cameras. A Heterogeneous Stereo Vision System (HSVS) is developed for three-dimensional (3D) measurement, which consists of a telecentric and a perspective camera. The depth-invariant property of the telecentric imaging and the relative wider coverage of the perspective vision jointly facilitate the 3D measurements in some specific scenarios. A novel methodology for calibrating the HSVS is proposed, in which the pose ambiguity of the telecentric camera is solved in a more concise way. In addition, the stereo geometry parameters are optimized under the transformation consistency constraint to improve the accuracy and robustness. Experiments show that the proposed HSVS preserves high accuracy (an average distance deviation of 0.012 mm) within a relative lager working volume than that of a stereo vision system composed of two telecentric cameras.