| Currently, Persistent Scatterer Synthetic Aperture Radar Interferometry (PSI) has been a hot topic in the field of international remote sensing, and has a great application potential in deformation monitoring. Up to now, it is less than13years since PSI technique was acknowledged and introduced into China. During this period, a great of investigations have been performed by scholars and groups, and some successful applications have been implemented. Nevertheless, the vocational operation for applying PSI to deformation monitoring has still not been realized. One restraint is the data source of SAR is hardly obtained. Another one is that it needs a further improvement and perfection for some key techniques, e.g., the effective identification and selection of persistent scatterer (PS) points, optimization of interference pairs, as well as high-precision estimation of deformation quantity. In this thesis, the PSI technique is chosen as a major subject in order to improve the accuracy and reliability for applying PSI to region deformation monitoring. Generally, the research contents can be concluded as follows:The existing mathematic models and its solutions for deformation monitoring by using PSI technique are compared and analyzed, comprehensively and systematically. The existing practical procedures of data processing are also concluded.The methods of identification and selection of PS points involved in PSI are discussed in details and an innovative practical procedure and method of data processing is given. An improved method for PS detection is presented, and corresponding experiments by using practical SAR images are performed. Its feasibility is confirmed and analyzed both theoretically and experimentally. Based on the method, spatial correlations of every phase components in PSI modeling are discussed in details.Interferometric processing of time series of SAR images is one of important parts in PSI technique for monitoring ground deformation. The mode of interferometric combination directly affects the quality of interferometric phases. In order to implement optimization of interference pairs, an improved interferometric combination mode based on traditional ways is proposed by considering the thresholds of both spatial and temporal baselines, and also taking into account the noise level in interferometric phases of all interferometric pairs. The testing results show that the minimum interferometric pairs and more persistent scatterers can be obtained by the proposed method, and the subsidence rate error derived by PSI is±3.89mm/yr with the ground-based measurements derived by precise leveling. This demonstrates that the proposed interferometric mode is viable and effective.Based on high resolution PSI technique, numerical experiments of subsidence monitoring are performed. Using practical SAR data, the ground subsidence of Shanghai city are investigated. Some major conclusions can be listed as follows:(1) The maximum relative subsidence rate in the study area is as high as-47mm/yr and the averaged subsidence rate is-16.96mm/yr;(2) Three centers of subsidence are more obvious, namely Baoshan Industrial Park in Luo Jing Town, Hongkou Football Stadium and Minhang Economic and Technological Development Zone;(3) The land subsidence has gradually extended to north, south, southwest, and southeast along with urban construction;(4) The experiment results have been validated with leveling data and the accuracy is±6mm/yr, which shows that the PSI technique have a great advantage in monitoring urban ground deformation. |
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