SPEC Method—A Fine Coregistration Method for SAR Interferometry

There is increasing demand for landscape acquisition using interferometric synthetic aperture radar for frequent Earth observation. Making an accurate digital elevation model (DEM) from an interferogram is often seriously affected by a mass of singular points (SPs) included in the interferogram. The origin of a type of SPs lies in inaccurate coregistration in making the interferogram. However, there have not been any method more effective than affine transformation based on cross correlation. Numerous research works have aimed at how to process the SPs resulting in the coregistration. In this paper, contrarily, we propose an additional method of local and nonlinear coregistration which employs the number of SPs as the evaluation criterion. This method provides us with an interferogram to generate a more accurate DEM. Experiments demonstrate that, with the proposed method, we can obtain a DEM having higher signal-to-noise ratios.