InSAR and A-InSAR: Theory

De-noising interferogram inSAR using variance and absolute deviation functions

“…The Interferometric Synthetic Aperture Radar (inSAR) imagery is a widely used technique comparatively with the optical imagery dint of its performance with own illumination source which is the UHF and SHF EM waves (XCL bands). This technique uses two antennas separated by a baseline to receive two correlated signals resulting a complex signal (Hooper, 2014; Filippo et al , 2005; Kim and Griffiths, 1999; Dukhopelnikova, 2004) so two types of images can be provided: magnitude and phase image, the second one is not directly exploited because it is wrapped into [−π,π] and to get the real elevation it should be unwrapped. If there is no noise, the unwrapping process is very easy by performing a simple two-dimensional integration, but if the interferogram is noised; because of the shadow region, under sampling or acquisition error, the application of the simple integration makes the unwrapped image distorted; several unwrapping methods have been proposed in the spatial or frequency field (Baldi et al , 2002; Li and Zhu, 2009; Ghiglia and Pritt, 1998; Filippo et al , 2005; Goldstein et al , 1988; Flynn, 1997; Shi and Zhang, 2008; Wang et al , 2014), in path following or minimum norm categories.…”