Interferometric synthetic aperture radar (InSAR) coherence is valuable information used for quantifying the degree of accuracy of the interferometric phase (interferogram). We propose two new algorithms for InSAR filtering based on the coherence map. These are complementary algorithms for accurate InSAR phase filtering in the wavelet domain. The first algorithm is an enhanced version of the López and Fabregàs filter, called wavelet interferometric phase filter (WInPF), where the main improvement is in the noise mask growing step. The new algorithm overcomes the limited accuracy of noise mask computation used in the “Filtrage par Approche Multiéchelle Modifié” (FAMM) algorithm by giving more accurate noise mask values with respect to the InSAR coherence information. The second approach proposed in this paper looks at reducing the impulse noise still tainting the SAR interferogram after operating the WInPF or the FAMM. Thus, we propose an improved version of the adaptive switching median filter dedicated to the case of the interferograms, which takes into account the corresponding coherence map values. The proposed approaches are validated on simulated interferograms and tested on real InSAR data acquired with the Radarsat-2 and Envisat satellites over Mahdia in Tunisia (North Africa) and Mount Etna in Italy (Europe).
This paper deals with a new exact formulation using SAR interferometry approach to extract accurate terrain elevation. By using the geometric formulation relating the elevation of a ground point to the phase difference of SAR images, we obtain an exact third order expansion with Maple software. Compared with this expansion, the second order one presents an error which can be expressed in terms of fringes shift in the interferogram. As the geometric InSAR formulation is different from one author to another, we present the utility of our work, and compare our results with those obtained by Lin (1991). We demonstrate that our more general formulation yields the development adopted by Prati and Rocca for interferogram generation. We also describe the procedure for phase generation from interferometric image pair. The baseline computation depends on the choice of the path length difference that we decide to adopt. By the same way, we illustrate the effects of the earth rotundity on the map resolution accuracy.
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