In the past two decades,extensive and in-depth research has been conducted on Time Series InSAR technology with the advancement of high-performance SAR satellites and the accumulation of big SAR data.The introduction ...In the past two decades,extensive and in-depth research has been conducted on Time Series InSAR technology with the advancement of high-performance SAR satellites and the accumulation of big SAR data.The introduction of distributed scatterers in Distributed Scatterers InSAR(DS-InSAR)has significantly expanded the application scenarios of InSAR geodetic measurement by increasing the number of measurement points.This study traces the history of DS-InSAR,presents the definition and characteristics of distributed scatterers,and focuses on exploring the relationships and distinctions among proposed algorithms in two crucial steps:statistically homogeneous pixel selection and phase optimization.Additionally,the latest research progress in this field is tracked and the possible development direction in the future is discussed.Through simulation experiments and two real InSAR case studies,the proposed algorithms are compared and verified,and the advantages of DS-InSAR in deformation measurement practice are demonstrated.This work not only offers insights into current trends and focal points for theoretical research on DS-InSAR but also provides practical cases and guidance for applied research.展开更多
The generation of high-resolution DEM from interferometric SAR has resulted in the need for accurate and efficient methods of 2-dimensional phase unwrapping. In this paper, we give a brief description of the mathemati...The generation of high-resolution DEM from interferometric SAR has resulted in the need for accurate and efficient methods of 2-dimensional phase unwrapping. In this paper, we give a brief description of the mathematical base of phase unwrapping, and a detailed description of the unweighted and weighted least square phase unwrapping algorithm.Then our algorithm combining with the weighted least square phase unwrapping guided by the branch-cuts derived from Goldstein’ s algorithm and coherence coefficient map derived from the INSAR data is provided. In our experiment we write subroutines of the Goldstein’s branch-cut algorithm,unweighted and weighted least square phase unwrapping algorithm as well as our algorithm,and construct a small experiment system to resolve the phase unwrapping problem. Finally we test our algorithm on some INSAR data. The result shows that our approach can obtain unwrapped phase correctly and efficiently.展开更多
Interferometric Synthetic Aperture Radar (InSAR) allows production of high resolution DEM and detection of small earth motions using multiple pass SAR data sets obtained by remote sensing satellite. But the whole proc...Interferometric Synthetic Aperture Radar (InSAR) allows production of high resolution DEM and detection of small earth motions using multiple pass SAR data sets obtained by remote sensing satellite. But the whole process has not yet reached sufficient robustness to warrant automated DEM production as commonly produced by stereovision with optical images. The automatic algorithm for precision registration is one of the bottlenecks in InSAR data processing. In this paper, an automatic approach with multi-step image matching algorithm is presented. All procedures are automatically implemented. The experiment is carried out successfully with SIR-C/L-band InSAR data. The triangular piecewise rectification is also advanced in reducing local distortion between the images and processing the large scene image. The primary result has prospect in the precision registration for the repeat-track InSAR data and reveals the potential of the presented automatic strategy.展开更多
In Synthetic Aperture Radar (SAR) interferometry, the precise co-registration is a key problem to obtain the fine interferogram. Theoretically, 1/10 pixel accuracy is essential. Once the control points are determined,...In Synthetic Aperture Radar (SAR) interferometry, the precise co-registration is a key problem to obtain the fine interferogram. Theoretically, 1/10 pixel accuracy is essential. Once the control points are determined, the relative rectification (pixel re-sampling)is also the important procedure. In this paper,a piecewise transformation algorithm based on Delaunay Tessellation algorithm is developed. The strategy is to 'anchor' geographically all control points and transform the imagery on the basis of triangle by triangle. The piecewise algorithm, the accuracy evaluation and the preliminary results are described. The experiment result shows that the piecewise transformation out-performes the traditional polynomial transformation.展开更多
Constrained by complex imaging mechanism and extraordinary visual appearance,change detection with synthetic aperture radar(SAR)images has been a difficult research topic,especially in urban areas.Although existing st...Constrained by complex imaging mechanism and extraordinary visual appearance,change detection with synthetic aperture radar(SAR)images has been a difficult research topic,especially in urban areas.Although existing studies have extended from bi-temporal data pair to multi-temporal datasets to derive more plentiful information,there are still two problems to be solved in practical applications.First,change indicators constructed from incoherent feature only cannot characterize the change objects accurately.Second,the results of pixel-level methods are usually presented in the form of the noisy binary map,making the spatial change not intuitive and the temporal change of a single pixel meaningless.In this study,we propose an unsupervised man-made objects change detection framework using both coherent and incoherent features derived from multi-temporal SAR images.The coefficients of variation in timeseries incoherent features and the man-made object index(MOI)defined with coherent features are first combined to identify the initial change pixels.Afterwards,an improved spatiotemporal clustering algorithm is developed based on density-based spatial clustering of applications with noise(DBSCAN)and dynamic time warping(DTW),which can transform the initial results into noiseless object-level patches,and take the cluster center as a representative of the man-made object to determine the change pattern of each patch.An experiment with a stack of 10 TerraSAR-X images in Stripmap mode demonstrated that this method is effective in urban scenes and has the potential applicability to wide area change detection.展开更多
C- and X-bands Synthetic Aperture Radar（SAR） images acquired from February 2009 to September 2010 were processed with Persistent Scatterer Interferometry（PS-InSAR） algorithm to investigate spatial and temporal var...C- and X-bands Synthetic Aperture Radar（SAR） images acquired from February 2009 to September 2010 were processed with Persistent Scatterer Interferometry（PS-InSAR） algorithm to investigate spatial and temporal variations in deformation over Taiyuan City, China. The spatial pattern of subsidence and the magnitude of subsidence rate are similar in the velocity field maps achieved by the algorithm from these two data sets. It shows that there are four primary subsidence centers in Taiyuan City：Xiayuan, Wujiabao, Xiaodian, Sunjiazhai, which are near the groundwater extraction wells. The maximum subsidence rate is up to 70 mm/year at Sunjiazhai. The locus of maximum subsidence has shifted from its historical location in the north to the south. In view of the severe shortage of water resources and presented features of subsidence over Taiyuan City, we inferred that excessive pumping of groundwater was the dominant reason of land subsidence.展开更多
基金National Natural Science Foundation of China(No.42374013)National Key Research and Development Program of China(Nos.2019YFC1509201,2021YFB3900604-03)。
文摘In the past two decades,extensive and in-depth research has been conducted on Time Series InSAR technology with the advancement of high-performance SAR satellites and the accumulation of big SAR data.The introduction of distributed scatterers in Distributed Scatterers InSAR(DS-InSAR)has significantly expanded the application scenarios of InSAR geodetic measurement by increasing the number of measurement points.This study traces the history of DS-InSAR,presents the definition and characteristics of distributed scatterers,and focuses on exploring the relationships and distinctions among proposed algorithms in two crucial steps:statistically homogeneous pixel selection and phase optimization.Additionally,the latest research progress in this field is tracked and the possible development direction in the future is discussed.Through simulation experiments and two real InSAR case studies,the proposed algorithms are compared and verified,and the advantages of DS-InSAR in deformation measurement practice are demonstrated.This work not only offers insights into current trends and focal points for theoretical research on DS-InSAR but also provides practical cases and guidance for applied research.
基金Project supported by the National Natural Science Foundation of China(No.69782001)
文摘The generation of high-resolution DEM from interferometric SAR has resulted in the need for accurate and efficient methods of 2-dimensional phase unwrapping. In this paper, we give a brief description of the mathematical base of phase unwrapping, and a detailed description of the unweighted and weighted least square phase unwrapping algorithm.Then our algorithm combining with the weighted least square phase unwrapping guided by the branch-cuts derived from Goldstein’ s algorithm and coherence coefficient map derived from the INSAR data is provided. In our experiment we write subroutines of the Goldstein’s branch-cut algorithm,unweighted and weighted least square phase unwrapping algorithm as well as our algorithm,and construct a small experiment system to resolve the phase unwrapping problem. Finally we test our algorithm on some INSAR data. The result shows that our approach can obtain unwrapped phase correctly and efficiently.
基金Project supported by the National Natural Science Foundation of China(No.69782001)
文摘Interferometric Synthetic Aperture Radar (InSAR) allows production of high resolution DEM and detection of small earth motions using multiple pass SAR data sets obtained by remote sensing satellite. But the whole process has not yet reached sufficient robustness to warrant automated DEM production as commonly produced by stereovision with optical images. The automatic algorithm for precision registration is one of the bottlenecks in InSAR data processing. In this paper, an automatic approach with multi-step image matching algorithm is presented. All procedures are automatically implemented. The experiment is carried out successfully with SIR-C/L-band InSAR data. The triangular piecewise rectification is also advanced in reducing local distortion between the images and processing the large scene image. The primary result has prospect in the precision registration for the repeat-track InSAR data and reveals the potential of the presented automatic strategy.
基金Project supported by the National Natural Science Foundation of China(No.69782001)
文摘In Synthetic Aperture Radar (SAR) interferometry, the precise co-registration is a key problem to obtain the fine interferogram. Theoretically, 1/10 pixel accuracy is essential. Once the control points are determined, the relative rectification (pixel re-sampling)is also the important procedure. In this paper,a piecewise transformation algorithm based on Delaunay Tessellation algorithm is developed. The strategy is to 'anchor' geographically all control points and transform the imagery on the basis of triangle by triangle. The piecewise algorithm, the accuracy evaluation and the preliminary results are described. The experiment result shows that the piecewise transformation out-performes the traditional polynomial transformation.
基金supported by the National Natural Science Foundation of China(41774006)the Comparative Study of Geo-environment and Geohazards in the Yangtze River Delta and the Red River Delta Projectthe Shanghai Science and Technology Development Foundation(20dz1201200)。
文摘Constrained by complex imaging mechanism and extraordinary visual appearance,change detection with synthetic aperture radar(SAR)images has been a difficult research topic,especially in urban areas.Although existing studies have extended from bi-temporal data pair to multi-temporal datasets to derive more plentiful information,there are still two problems to be solved in practical applications.First,change indicators constructed from incoherent feature only cannot characterize the change objects accurately.Second,the results of pixel-level methods are usually presented in the form of the noisy binary map,making the spatial change not intuitive and the temporal change of a single pixel meaningless.In this study,we propose an unsupervised man-made objects change detection framework using both coherent and incoherent features derived from multi-temporal SAR images.The coefficients of variation in timeseries incoherent features and the man-made object index(MOI)defined with coherent features are first combined to identify the initial change pixels.Afterwards,an improved spatiotemporal clustering algorithm is developed based on density-based spatial clustering of applications with noise(DBSCAN)and dynamic time warping(DTW),which can transform the initial results into noiseless object-level patches,and take the cluster center as a representative of the man-made object to determine the change pattern of each patch.An experiment with a stack of 10 TerraSAR-X images in Stripmap mode demonstrated that this method is effective in urban scenes and has the potential applicability to wide area change detection.
基金Supported by the National Natural Science Foundation of China(61331016)
文摘C- and X-bands Synthetic Aperture Radar（SAR） images acquired from February 2009 to September 2010 were processed with Persistent Scatterer Interferometry（PS-InSAR） algorithm to investigate spatial and temporal variations in deformation over Taiyuan City, China. The spatial pattern of subsidence and the magnitude of subsidence rate are similar in the velocity field maps achieved by the algorithm from these two data sets. It shows that there are four primary subsidence centers in Taiyuan City：Xiayuan, Wujiabao, Xiaodian, Sunjiazhai, which are near the groundwater extraction wells. The maximum subsidence rate is up to 70 mm/year at Sunjiazhai. The locus of maximum subsidence has shifted from its historical location in the north to the south. In view of the severe shortage of water resources and presented features of subsidence over Taiyuan City, we inferred that excessive pumping of groundwater was the dominant reason of land subsidence.
