Abstract
Persistent scatterers (PS) interferometry tools are extensively used for the monitoring of slow, long-term ground deformation. High spatial resolution is typically required in urban areas to cope with the variability of the signal, whereas in rural regions, multilook shall be implemented to improve the coverage of monitored areas. Along this line, SqueeSAR and later Component extrAction and sElection SAR (CAESAR) were introduced for the monitoring of both persistent and (decorrelating) distributed scatterers (DS). Multilook generalized likelihood ratio test (MGLRT) is a detector derived in the context of tomographic SAR processing that has been investigated for a fixed multilook degree. In this work, we address MGLRT and CAESAR in the multiresolution context characterized by a spatially variable multilook degree. We compare the two schemes for the multiresolution selection of PS and DS, highlighting the pros and cons of each scheme, particularly the peculiarities of CAESAR that have important implications at the implementation stage. A performance analysis of both detectors in case of model mismatch is also addressed. Experiments carried out with data acquired by the COSMO-SkyMed constellation support both the theoretical argumentation and the results achieved by resorting to Monte Carlo simulations.
Highlights
M ETHODS for the coherent, that is interferometric, processing of multitemporal SAR data handle the detection of persistent scatterers (PS) via the measurement of the degree of correlation between the data stack and a proper parametric model, so to extract reliable information from the estimated parameters [1], [2]
A performances comparison of Multilook generalized likelihood ratio test (MGLRT) and Component extrAction and sElection SAR (CAESAR)-D for the detection of single scatterers has been carried out on a real SAR data set composed by 32 images acquired from December 7, 2011 to January 13, 2014 by the COSMOSkyMed constellation operating in H-Image mode on ascending orbits over the northern surroundings of the city of Naples (South Italy)
The work has addressed the comparison of two multilook approaches for the detection of equivalent” PS (ePS) introduced in the literature: CAESAR-D and MGLRT
Summary
M ETHODS for the coherent, that is interferometric, processing of multitemporal SAR data handle the detection of persistent scatterers (PS) via the measurement of the degree of correlation between the (complex) data stack and a proper parametric model, so to extract reliable information from the estimated parameters [1], [2]. VERDE et al.: MULTIRESOLUTION DETECTION OF PS: PERFORMANCE COMPARISON BETWEEN MGLRT AND CAESAR resolution) deformation signal Such estimates are used for the phase calibration of the data, which are fed to the second step involving an analysis at high-spatial frequencies, generally carried out at full or close-to-full resolution. A main contribution is the (analytical) demonstration that CAESAR-D has a PFA independent of the number of looks and equal to the one of single-look GLRT (SGLRT) This feature has important implication from the application point of view, especially in the case of implementation, as of main interest in this work, of a spatially adaptive multilook detection of PS/ePS, characterized by a constant (over the image) PFA level.
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