In‐orbit geometric calibration and validation of ZY ‐3 three‐line cameras based on CCD ‐detector look angles

A simple and feasible orientation method for the three‐line cameras of the ZiYuan‐3 (ZY‐3) satellite is introduced. The method calibrates the CCD‐detector look angles in the attitude determination reference (ADR) coordinate system rather than modifying the laboratory‐calibrated orientation parameters, which are not necessary for the geometric calibration. Additionally, the unknown parameters of the model are virtually uncorrelated. Experimental results show that the direct georeferencing accuracy of ZY‐3 nadir images have been improved from the kilometre level to better than 9 m in planimetry, and that of the forward‐and‐backward stereopair was also raised to better than 18 m in plan and 4 m in height. After a bundle adjustment using four ground control points, a higher accuracy of about 3·4 m in plan and 1·6 m in height was achieved.