Abstract:

The navigation precision can be improved when a synthetic aperture radar (SAR) is used. However, inherent geometric distortion of SAR images under undulate areas increases the navigation error. Since it is difficult to acquire GCP with high precision under undulate areas, a three-step method of SAR image geome-tric correction is proposed. First, the range position error caused by terrain is rectified in the slant range plane through a digital elevation model (DEM). Then the scale error between slant and ground range is corrected in the ground range plane. Finally, the reference frame of the real-time image is transformed into navigation coordinate system according to the course angle. A detailed description of the method together with a complication and precision analysis is presented. In the end, a simulation based on the real DEM data testifies the method’s validity and accuracy.