An automated method to estimate the baseline parameters for deriving the accurate digital elevation model

摘要

This paper describes a Synthetic Aperture Radar (SAR) phase processing system and an automated method for estimating baseline length and its inclination angle from only pair of Single Look Complex (SLC) images to be interfered. The information about the baseline parameters are indispensable to produce accurate Digital Elevation Model (DEM) without geometrical distortion and also accurate displacement from differential Interferometric SAR (InSAR) processing. Only the nominal value of the baseline length is currently provided. The fixed value, however, does not represent nonparallel orbits from which raw interferogram is obtained. The ambiguity causes the geometrical distortion in DEM and the apparent displacement in the result of differential InSAR processing. In order to produce the accurate DEM, we have to know the baseline parameters as the function of the azimuth line. The proposed method derives coefficients of both functions for baseline length and for inclination angle by fitting the local disparities to a geometrical model. The proposed method was successfully applied to an actual InSAR data. The baseline estimated by the proposed method reduced apparent displacement to 1 / 10 of that yielded by the nominal baseline. A piecewise co-registration method is also described for obtaining highly accurate interferogram.