In-Orbit Geometric Calibration Without Accurate Ground Control Data

摘要

In-orbit geometric calibration is a key technology for improving the geometric positioning accuracy of satellites. Conventional geometric calibration, which uses high-accuracy ground control data to accurately calibrate the orientation parameters of a satellite, heavily relies on the control data of the calibration fields and may not be applicable in emergencies where urgent and accurate positioning is needed. The constant calibration of satellites is also difficult owing to the lack of permanent calibration fields. This paper presents a geometric cross-calibration method for the rapid and accurate calibration of satellites. The conjugate points from the multitemporal images of one satellite or multi-satellite images are first automatically extracted; then, the interior orientation parameters of the satellite requiring calibration can be precisely recovered according to the positioning consistency constraint of the conjugate points. In contrast to the conventional method, the proposed method can accurately calibrate the orientation parameters without using high-accuracy control data of the calibration fields. Therefore, the proposed method aids in the constant calibration of satellites to ensure the positioning accuracy, even without sufficient permanent calibration fields. The multitemporal images of the Yaogan-4 satellite and the images of the ZY3-01 and ZY02C satellites were considered for verifying this method. Finally, accuracies of approximately 0.7 and 0.6 pixels were achieved by the proposed and conventional methods, respectively. The difference between the two methods was only approximately 0.1 pixels, demonstrating that the proposed method can achieve a calibration accuracy as high as that achieved by the conventional method, even without the use of high-accuracy control data.