Polarimetric Temporal Analysis of Urban Environments With a Ground-Based SAR

• Published in: IEEE transactions on geoscience and remote sensing Vol. 51; no. 4; pp. 2343 - 2360
• Main Authors: Pipia, L., Fabregas, X., Aguasca, A., Lopez-Martinez, C.
• Format: Journal Article Publication
• Language: English
• Published: New York, NY IEEE 01.04.2013; Institute of Electrical and Electronics Engineers; Institute of Electrical and Electronics Engineers (IEEE)
• Subjects: Applied geophysics; Backscatter; Earth sciences; Earth, ocean, space; Enginyeria de la telecomunicació; Exact sciences and technology; Geologic measurements; Ground-based synthetic aperture radar (gbSAR) systems; Internal geophysics; Monitoring; polarimetric entropy; Radar; radar polarimetry; Radiocomunicació i exploració electromagnètica; Remote sensing; Scattering; Stability analysis; Synthetic aperture radar; Teledetecció; Urban areas; Àrees temàtiques de la UPC; Iberian Peninsula; Southern Europe; Europe; Spain; experimental studies; polarimetry; Groundbased synthetic aperture radar (gbSAR) systems; urban environment; Space remote sensing; remote sensing; mining; backscattering; radar polarimetry; entropy; polarimetric entropy; subsidence; filtering; radar methods; Synthetic aperture radar; stability
• ISSN: 0196-2892; 1558-0644
• DOI: 10.1109/TGRS.2012.2211369

Revisiting time constitutes a key constraint for continuous monitoring activities based on space- and airborne synthetic aperture radar (SAR) acquisitions. Conversely, the employment of terrestrial platforms overcomes this limitation and makes it possible to perform time-continuous observations of small space-scale phenomena. New research lines of SAR dealing with the backscattering evolution of different types of scenarios become hence possible through the analysis of ground-based SAR (gbSAR) data collections. The Remote Sensing Laboratory of the Universitat Politècnica de Catalunya drove a one-year measurements campaign in the village of Sallent, northeastern Spain, using its X-Band gbSAR sensor. The field experiment aimed at studying the subsidence phenomenon induced by the salt mining activity carried out in this area during the past decades. In this paper, the polarimetric behavior of an urban environment is investigated at different time scales. After a brief description of the test site and the measurement campaign, the analysis is focused on the stability on man-made structures at different time scales. PolSAR data monthly acquired from June 2006 to July 2007 are employed to stress the presence of nonstationary backscattering processes within the urban scene and the effect they have on differential phase information. Then, a filtering procedure aiming at reducing backscattering randomness in one-day and long-term data collections is then put forward. The improvements provided by the proposed technique are assessed using a new polarimetric descriptor, the time entropy. In the end, the importance of preserving the interferometric phase information from nonstationary backscattering contaminations using fully polarimetric data is discussed.