Flexible calibration of camera with large FOV based on planar homography

In order to achieve the high precision calibration of camera with large FOV (field-of-view), sufficient calibration points uniformly distributed in the FOV are needed. However, the arrangements of calibration points are normally complicated and time-consuming; meanwhile, the precision of the assigned calibration points is difficult to guarantee. To solve this problem, a flexible calibration method based on planar homography is presented. In this method, a large scale calibration target covering the whole FOV is built with several feature points by means of homography, in which camera distortion is fully considered so as to pledge the precision of the constructed calibration points. Simultaneously, classical Tsai method is improved in the process of calibration so as to adapt the constructed calibration target, which makes the whole process of calibration linear. The experiments results show that the precision of the flexible calibration based on planar homography is equivalent to that of calibration with real large scale target, whose reconstruction error is within 1.5 mm with the FOV of 3000 mm × 4000 mm. The method presented in this paper can achieve the high precision calibration of camera with large FOV.