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Remote Sens. 2019, 11(3), 356; https://doi.org/10.3390/rs11030356

New Approaches for Robust and Efficient Detection of Persistent Scatterers in SAR Tomography

1
College of Electronic Science, National University of Defense Technology, No. 109 De Ya Road, Changsha 410073, China
2
China Electronic Technology Group Corporation (CETC), Wan Shou Road, Beijing 100000, China
*
Author to whom correspondence should be addressed.
Received: 3 January 2019 / Revised: 3 February 2019 / Accepted: 3 February 2019 / Published: 11 February 2019
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Abstract

Persistent scatterer interferometry (PSI) has the ability to acquire submeter-scale digital elevation model (DEM) and millimeter-scale deformation. A limitation to the application of PSI is that only single persistent scatterers (SPSs) are detected, and pixels with multiple dominant scatterers from different sources are discarded in PSI processing. Synthetic aperture radar (SAR) tomography is a promising technique capable of resolving layovers. In this paper, new approaches based on a novel two-tier network aimed at robust and efficient detection of persistent scatterers (PSs) are presented. The calibration of atmospheric phase screen (APS) and the detection of PSs can be jointly implemented in the novel two-tier network. A residue-to-signal ratio (RSR) estimator is proposed to evaluate whether the APS is effectively calibrated and to select reliable PSs with accurate estimation. In the first-tier network, a Delaunay triangulation network is constructed for APS calibration and SPS detection. RSR thresholding is used to adjust the first-tier network by discarding arcs and SPS candidates (SPSCs) with inaccurate estimation, yielding more than one main network in the first-tier network. After network adjustment, we attempt to establish reliable SPS arcs to connect the main isolated networks, and the expanded largest connected network is then formed with more manual structure information subtracted. Furthermore, rather than the weighted least square (WLS) estimator, a network decomposition WLS (ND-WLS) estimator is proposed to accelerate the retrieval of absolute parameters from the expanded largest connected network, which is quite useful for large network inversion. In the second-tier network, the remaining SPSs and all the double PSs (DPSs) are detected and estimated with reference to the expanded largest connected network. Compared with traditional two-tier network-based methods, more PSs can be robustly and efficiently detected by the proposed new approaches. Experiments on interferometric high resolution TerraSAR-X SAR images are given to demonstrate the merits of the new approaches. View Full-Text
Keywords: Persistent scatterer interferometry (PSI); SAR tomography; persistent scatterer (PS); atmospheric phase screen (APS); two-tier network; RSR estimator; ND-WLS estimator; TerraSAR-X Persistent scatterer interferometry (PSI); SAR tomography; persistent scatterer (PS); atmospheric phase screen (APS); two-tier network; RSR estimator; ND-WLS estimator; TerraSAR-X
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
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Zhu, X.; Dong, Z.; Yu, A.; Wu, M.; Li, D.; Zhang, Y. New Approaches for Robust and Efficient Detection of Persistent Scatterers in SAR Tomography. Remote Sens. 2019, 11, 356.

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