Constructing method of calibration feature points used for circle structure light vision sensor

Pipe is one of the most important transmission modes in industry and the detection of the in-pipe surface is necessary to ensure the transmission safety. Circle structure light vision sensor is extensively used to measure the three-dimensional size of devices because of its characteristics of high precision, large information and non contact. The calibration of the circle structure light vision sensor is the most important step to realize the measurement. A novel constructing method of calibration feature points for circle structure light vision sensor was proposed based on coplanar reference object. First the calibration points were obtained based on the invariance of cross ratio in different plane position, then via the camera coordinate system, the transfromation between the different plane local coordinate system and the world coordinate system was realized, finally the space calibration feature points were constructed based on the world coordinate system. The proposed method greatly reduces the cost of the calibration equipment and simplifies the calibrating procedure. The calibration precision achieves 0.340 mm which proves the feasibility of the method.