1. A two-dimensional polar geometry model method used in a synthetic aperture radar (SAR) system for removing a two-dimensional phase error in a complex image, the method comprising: creating the complex image with a sensor; modeling the two-dimensional phase error as a combination of a range error which is substantially identical from pulse to pulse and a slow-time error; fitting an unconstrained two-dimensional estimate to the modeled two-dimensional phase error; and correcting the two-dimensional phase error to generate a corrected image.