A Comparison of the Different Models Used For Interferograms Flattening

For interferometric SAR (InSAR) processing, the precision of the interferometric phase is very important since it decides directly that of the final measurement. It is known that the interferometric phase is composed of many different parts such as the phase due to the topography, the possible deformation, the atmosphere, the track error and so on. Before doing phase-unwrapping, the interferogram must be flattened to decrease the density of the fringes in the interferogram or it may make phase unwrapping fail. For the practical application of InSAR, if the interferogram is not flattened well, the residual phase due to the earth will be considered to be the phase due to the topography or the deformation. In this paper the different earth reference models that have been used for doing flattening are analyzed. Some experiments have been done on the real images and the conclusions are given at the end.