BACK PROJECTION AND RATIONAL FUNCTION MODELING FOR SAR SATELLITE IMAGERY

摘要

Synthetic Aperture Radars (SARs) take the advantages of all-weather and day-and-night capabilities to acquire object information in microwave bands. In order to enhance the applications of SAR data, the geometric correction is a must. Thus, the generated orthoimage can be registered with other GIS data layers. The traditional methods for the rectification of SAR imagery adjust orbit polynomials according to ground control points. From direct georeferencing point of view, this paper investigates the feasibility of Radar back projection and analyzes the accuracy of proposed method to simplify the processing for SAR imagery rectification at first. Owing to the implementation and standardization of Rational Function Model (RFM), it is widely used in the optical sensor adjustment. This research also investigates the feasibility of RFM for radar images positioning. The major works include radar back projection and RFM. The proposed scheme for radar back projection includes (1) establishing the Radar back projection procedure, (2) linear transformation, and (3) least squares collocation. In addition, the proposed scheme for RFM includes (1) establishment of RFM, (2) linear transformation, and (3) least squares collocation. The experiments test the images for different satellites and, then, compare the proposed method with the Geomatica Toutin's model. The proposed method can reach similar or ever better results than Geomatica Toutin's model.