PROCESS FOR FILTERING INTERFEROGRAMS OBTAINED FROM SAR IMAGES ACQUIRED ON THE SAME AREA SAR

摘要

A process for filtering interferograms obtained from SAR images, acquired on the same area by synthetic aperture radars, comprising the following steps: a) acquiring a series of N radar images (Al . . . AN) by means of a SAR sensor on a same area with acquisition geometries such as to allow re-sampling of the data on a common grid; b) after re-sampling on a common grid, selecting a pixel from the common grid; c) calculating the coherence matrix of the selected pixel, that is estimating the complex coherence values for each possible pair of available images; d) maximizing, with respect of the source vector &thetas;, here an unknown element, the functional: (formula) being R the operator which extracts the real part of a complex number, γnm the modulus of the element (n,m) of the coherence matrix, k a positive real number, &phgr;nm the phase of the element (n,m) of the coherence matrix, &thetas;n and &thetas;m the elements n and m of the unknown vector &thetas;. Given that only phase differences appear in the functional T, the values of the unknown factor are estimated less an additive constant, which can be fixed by setting for example &thetas;1=0, and the phase values &thetas;n thus obtained constitute the vector of the filtered phase values. T = ⁢ { ∑ n = 1 N ⁢ ∑ m = 1 N ⁢ γ n ⁢ ⁢ m k · ⅇ ⅈ&phis; n ⁢ ⁢ m ⁢ ⅇ - ⅈ ⁡ ( &thetas; n - &thetas; m ) } ( I )