Analysis of Permanent Scatterers in SAR interferometry

In previous papers, it has been shown that stable and pointwise targets (Permanent Scatterers) can be identified from long temporal series of ERS SAR images. On the PS grid, all data can be exploited for displacement estimation, regardless of their temporal and geometrical baselines. In this paper, it will be shown how a first selection of PS (a key step in the PS technique) can be carried out by means of a statistical analysis of the amplitude time series, after radiometric correction. An example of this incoherent approach to PS candidates selection will be illustrated and discussed. The authors then present the results of a statistical analysis carried out on three different test sites (Milan, Paris and Los Angeles). More than 170 ERS acquisitions have been processed to get an estimation of the PS density as a function of phase noise. Results show that, in urban areas, about 100 PS/km/sup 2/ can be identified and exploited for terrain deformation monitoring with millimetric accuracy.