Multi-Link SAR interferograms: Enhancement of a wrapped interferometric database

Ground surface deformation can be monitored from time series of SAR interferograms. Conventional approaches to that problem usually require unwrapping of the interferograms that can be limiting due to decorrelation. We present a method producing denoised wrapped phase time series from a set of differential interferograms. The different paths linking two dates are combined to derive the most likely estimate of wrapped phase difference between these dates. The result is called a Multi-Tink SAR (MuLSAR) interferogram and is shown to have better signal-to-noise ratio than conventional interferogram. The technique also enhances the temporal resolution of an interferometric database as a MuLSAR can be computed for pairs of images for which no interferogram could be produced due to decorrelation. It can be used as a pre-processing to wrapped phase time series exploitation methods. The performance of the technique is demonstrated on a real dataset of ENVISAT images.