Evaluation of geometric accuracy and the features of TanDEM-X

The current study evaluated the geometric accuracy of TanDEM-X twice in-situ by simultaneous observations using several corner reflectors. We set the reflectors on the flat ground, and measured the position of the reflectors before and after the satellite pass using GPS and achieved the accuracies within several centimeters. We utilized the orthorectified product which performs the correction of the geometric distortion. The results indicated that the geometric tendency of TanDEM-X is almost similar with TerraSAR-X. We also evaluated the features for correcting the geometric distortion by examining the relationships between the geometric accuracy and incidence angle of the satellites and noted that the more the incidence angle, the better the geometric accuracy proportionally. This evaluation revealed that we can actually acquire the outputs predicted by the theoretical model. The latest series of our conducted studies specify the high geometric accuracies and reliability of the specifications of the TerraSAR-X and TanDEM-X, the newest commercially available SAR satellites.