Light probe based large FOV 3D vision measurement system

To meet the requirements of large-scale equipment for large scope precise measurement in advanced manufacturing industry, a light probe based large Field of View (FOV) 3D vision measurement system based on the binocular stereo vision principle was proposed. The spatial distribution mode of the character points on the light probe was determined according to the invariants of clockwise direction and colinearity under a perspective projection, by which the character points were recognized and the coordinates of the probe were calculated. By using a 3D measurement model based on perspective projection and the homogeneous coordinates of a binocular stereo vision sensor, the structure parameters of the binocular stereo vision sensor were calibrated through linearly solving the essential matrix E, further following with nonlinear optimization by freely moving a 1D target with known precise length. A true large FOV 3D vision measurement system was constructed, which consists of a light probe, a binocular 3D vision measurement system, a portable tripod, a 1D target and a set of measurement software. The real experiment to measure the dense 3D data was performed on a robot body surface in a field of 7 m × 4.7 m and the accuracy better than 0.2 mm was achieved. These results show that the designed system has improvement in the light probe structure, recognition methods of luminous points and the system calibration methods.