Two-step calibration method for extrinsic parameters of an airborne camera

In order to meet the accuracy requirements of target geo-location of a wide-area reconnaissance camera, it is necessary to calibrate the extrinsic parameters of the camera. A novel calibration method is proposed for the orientation relationship between the camera coordinate system (CCS) and the frame coordinate system (FCS). First, the calibration between the roll axis of the FCS and the CCS is carried out based on the method of the extended Kalman filter. Second, the calibration between the pitch axis of the FCS and the CCS is deduced based on the least mean square combined with the particle swarm optimization method. Then, the calibration accuracy of the proposed method is quantitatively analyzed by numerical simulation. Finally, a calibration experiment is conducted on verifying the effectiveness of the method.