Towards a revised framework of modified time series InSAR for mapping land deformation
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ORIGINAL ARTICLE
Towards a revised framework of modified time series InSAR for mapping land deformation Zheyuan Du1,2 · Linlin Ge1 · Alex Hay‑Man Ng1,3 · Qi Zhang1 Received: 28 February 2019 / Accepted: 10 August 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Interferometric synthetic aperture radar (InSAR) time series technique has been widely applied to map the ground deformation over the past two decades. One of the key steps of InSAR time series approach is to select appropriate measurement scatterer (MS) pixels to build the triangulated irregular network (TIN). In order to build a stable TIN, there are four criteria need to be satisfied: (1) working from whole to the part, (2) hierarchical network, step-by-step control, (3) with sufficient accuracy, and (4) with appropriate spatial density. The effectiveness of Geodesy and Earth Observing Systems-PSI (GEOS-PSI) and GEOS-Advance Time Series Analysis (GEOS-ATSA) approaches have met the first three criteria above. Nevertheless, it is noteworthy to mention that higher sparseness of the TIN may lead to unwrapping failures, while having more evenly distributed of MS offers a higher chance to eliminate such effect and include more additional pixels during the adaptive processing. In this work, we proposed a revised MS pixels selection approach to satisfy the fourth criterion, in combination with the GEOS-PSI and GEOS-ATSA processing chain: the modified GEOS-ATSA (GEOS-MATSA). As compared to the conventional MS pixels selection criterion, the proposed approach has three advantages: (1) the MS pixels are added into the main network with control through an adaptive estimation strategy, (2) isolated sub-networks have better chances of including into the main network, and (3) the computing workload can be decreased by reducing the iteration times. The case study area is selected in Beijing–Langfang region, while the ideal threshold settings for the initial reference network are discussed for both persistent scatterer and distributed scatterer pixels in this work. Keywords Control survey · InSAR · Time series · Triangulated irregular network
1 Introduction Interferometric synthetic aperture radar (InSAR) technique has been widely applied to high-accuracy measurements of surface topography and ground deformation thanks to its sensitivity to the range information (Bamler and Hartl 1998; Du et al. 2018a; Ng et al. 2017). Differential SAR interferometry (D-InSAR) technique is used for the measurement of * Zheyuan Du [email protected] 1
Geoscience and Earth Observing Systems Group (GEOS), School of Civil and Environmental Engineering, University of New South Wales (UNSW), Sydney, NSW 2052, Australia
2
School of Civil Engineering, University of Sydney, Camperdown, NSW 2006, Australia
3
Department of Surveying Engineering, Guangdong University of Technology, Guangzhou, China
the motion velocity or the detection of the surface changes, which uses two radar images acquired at different times from slightly different positions to form t
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