Impact of SAR image resolution on the performance of the amplitude dispersion optimization for polarimetric persistent scatterer interferometry

Polarimetric persistent scatterer interferometry (PolPSI) takes advantage of polarimetric optimization algorithms that enhance interferograms’ phase quality by adequately combining the available polarization channels (e.g., HH, VV, HV, and VH) into an improved one. Amplitude dispersion ( DA ) is one of the commonly used phase quality metrics for this optimization. The resolution of the images is supposed to have an impact on the performance of DA -based PolPSI in terms of both pixel density and quality. In this research, this impact is investigated. Specifically, 30 quad-pol RADARSAT-2 images over Barcelona with a resolution around 5 m in both range and azimuth are employed to generate additional data sets with degraded resolutions, ranging from 7.5 to 20 m. The results confirm that, in all cases, the ability of DA to select high-quality pixels, i.e., persistent scatterers, decreases when the spatial resolution worsens because the loss of resolution increases the number of scatterers present in a resolution cell. In addition, it would be expected that the performance of the polarimetric optimization of DA would tend to decrease when the spatial resolution worsens. However, for all employed resolutions, the polarimetric optimization improves the density and quality of PSs with respect to that of any single polarimetric channel. Moreover, this improvement is more noticeable, in relative terms, as the image resolution degrades.This work was supported in part by the Spanish Ministry of Economy, Industry and Competitiveness (MINECO), the State Research Agency (AEI) and the European Funds for Regional Development (EFRD) under Project TEC2017-85244-C2-1-P and Project TEC2017-85244-C2-2-P, in part by the National Natural Science Foundation of China under Grant 42004011 and Grant 41874044, in part by the China Postdoctoral Science Foundation under Grant 2020M671646, in part by the Priority Academic Program Development (PAPD) of Jiangsu Higher Education Institutions (Science and Technology of Surveying and Mapping), and in part by the CommSensLab, which is Unidad de Excelencia Maria de Maeztu MDM-2016-0600 financed by the AEI, Spain.Peer ReviewedPostprint (author's final draft