A Grid Recognition-Based Calibration Algorithm for Measuring System

To achieve the calibration parameters of vision measurement system, this paper presents a new camera calibration method based on grid recognition. The calibration is implemented by acquiring the corresponding relations between the world coordinates and pixel coordinates of the planar gridding target image captured by camera. Meanwhile, the pixel coordinates of the target image are detected separately by getting the binary image with the Otsu binarization algorithm, recognizing the target grid point using the improved hit-or-miss transform (HMT), removing the interferences according to the geometrical features of the grid, correcting the system distortion by the least square fitting and bilinear interpolation algorithm, and achieving the accurate pixel coordinates finally. The precision, feasibility, and reliability are verified by experiments, results shows that the proposed camera calibration method is suitable for image measurement systems, displacement measurement systems and other engineering applications.