短基线集技术的合肥地表形变监测研究

针对如何利用InSAR技术持续性监测合肥市重点区域地表形变的问题,该文提出了一种利用COSMOSkyMed影像数据,基于短基线集技术反演2011—2016年度合肥地区地表形变的方法。结果表明:合肥市重点区域在2011—2016年期间地面形变呈平稳态势,年均形变速率在-5mm/a到5mm/a的地面形变点数量占总地面形变点数量超过95%。技术人员利用研究区内的CORS监测数据与InSAR监测的形变结果进行比较分析后发现,两者间具有较好的一致性,年形变速率差异的均方差为0.3mm/a。     

利用短基线集技术监测地表形变

针对合成孔径雷达干涉测量(D-InSAR)技术由于受时间、空间失相干和大气延迟两大因素的影响,不能在地面沉降灾害监测方面得到较好应用的问题,该文对合成孔径雷达干涉测量小基线集(SBAS-InSAR)技术在地表形变监测中的适用性进行了研究。利用22景ALOS雷达影像开展了西安市地面沉降监测试验,并通过时间序列分析的方法获取了2007年1月到2011年2月时间段内西安市的高精度地表形变成果。实验结果表明,该成果与同时间内GPS、水准结果吻合较好。因此,该技术可广泛应用于城市地表形变监测,为相关部门决策提供科学可靠的数据参考。     

时间序列InSAR技术中的形变模型研究

时间序列InSAR技术,包括PS-InSAR技术和小基线集InSAR技术, 能有效克服传统D-InSAR的失相干限制, 逐步成为形变测量中的实用化技术。但是, 现有时间序列InSAR技术主要采用线性函数对真实形变进行模拟, 在真实形变呈现强烈的非线性时, 这种处理将不能得到正确的形变结果。本文就时间序列InSAR的形变模型问题展开研究, 首先从干涉相位模型解算的方法入手, 深入分析了线性形变模型的不足, 当干涉点目标的密度不够并且真实形变的非线性较强时, 干涉相位方程的解将会发散。根据魏尔斯特拉斯逼近定理, 提出以高阶多项式取代线性形变模型, 并给出了基于多项式形变模型的干涉相位方程解算方法。 利用太原市2003-2009年的23景ENVISAT ASAR影像, 分别采用线性形变模型和三次多项式形变模型, 利用小基线集技术进行了形变反演。将这两种方法得到的结果分别与水准测量结果进行了比较。结果表明, 采用多项式形变模型不仅能取得更高的形变测量精度,而且能提高点目标的密度。由于高阶多项式总能比低阶多项式更准确地拟合连续函数, 因此本文提出的多项式形变模型在时间序列InSAR形变监测中具有广泛的应用价值。     

IPTA监测圣佩德罗湾港口地表时序沉降

常规D-InSAR技术已成功应用于由于火山、地震等引起的地表形变监测,然而受时间失相干和大气延迟等影响,该技术监测地表沉降形变的精度只能达厘米级。本文以美国圣佩德罗湾港口为研究对象,采用干涉点目标分析(IPTA)技术,选用二维线性相位模型对时序差分干涉相位图迭代回归分析,逐次去除大气延迟、DEM误差以及噪声等的影响,最终提取出准确可靠的形变序列相位信息。结果证明IPTA技术对长期微小的地壳累积形变探测具有广阔的应用前景,而且IPTA技术在实现效率和数据存储方面都优于常规的PS-InSAR。     

地表形变监测的改进相干目标法

如何从雷达干涉时间序列影像中获取更全面的相干目标集合,进行变形时间序列分析是当前研究的难点和热点。本文提出了改进的相干目标法,可获取更为全面且可信度高的相干目标集合,进而提高地表形变监测的时空分辨率和精度。根据雷达影像中同类型地物散射分布相近的特点,采用非参数同分布检验算法提取后向散射特性相近的同质点开展空间非局部滤波,提高干涉图的质量。与此同时,利用多尺度的极大似然条纹频率估计算法分离差分干涉图中的系统性相位,并基于同质点进行自适应相干性估计,获取相干性的平稳估计量,从而获取更多的相干点目标。利用20景TerraSAR-X条带模式时间序列影像,分别利用传统的及改进后的相干目标法对香港填海区域地表形变信息进行时序分析。对试验数据的分析结果表明,本文提出的改进方法在具有稀疏植被的填海区可有效增加相干目标点的提取,得到更为可信的沉降结果。     

InSAR时间序列分析技术在西安地表形变监测的应用

差分干涉测量技术（D-InSAR）是近年发展起来的新型空间对地观测技术,具有全天候、全天时、大范围地表形变监测优点,但由于受到时空失相干和大气延迟的影响,形变监测精度受到了很大的制约。近年发展起来的InSAR时间序列分析技术,将多景SAR影像数据融合在一起,利用时间序列分析提取监测区域监测期内的时间序列形变信息,间接消除或削弱了时空失相干和大气延迟对形变结果的影响,具有良好的应用前景。本试验利用InSAR时间序列分析技术获取了西安市三环以内主城区2007年1月至2011年2月间的高精度地表形变成果。     

小基线集技术在地面沉降监测中的应用

小基线集技术(SBAS-InSAR)是近年提出的一种新的InSAR时间序列分析方法,它能有效地克服时空时间和空间失相干现象等限制性因素,且具有可增加时间采样率,对影像数量要求不高等优点.本文详细介绍了SBAS技术形变监测原理,并利用22期ALOS卫星的PALSAR数据进行了试验,获取了西安市2007～2011年的时间序列形变值,成功地反演了该地区在2007年1月至2011年2月的地表形变时空演变过程.获取的西安市地表形变成果,对进一步认识地裂缝的演变发展、预报灾害以及城市的可持续发展具有深刻的指导意义.     

融合分布式目标的小基线集干涉测量方法应用

针对在地理国情监测项目中遇到的时间序列InSAR技术获取的地表形变结果存在空间采样率不足的现状,该文以传统小基线集干涉测量方法为基础,融合分布式目标提取地表缓慢形变信息。以TerraSAR-X星载SAR SLC影像为数据源,对融合后的方法进行验证,获取了研究区域时间序列地表平均形变速率。结果表明,融合分布式目标的小基线集算法可以有效提高监测区域地表形变信息的获取,在非城市地区及传统方法不能提取高相干稳定点目标的区域克服了原有方法的缺点,表现出了很好的适用性。     

改进小基线集技术的GB-InSAR铁路边坡监测

针对传统小基线集技术形变模型和高相干点识别存在的问题,该文利用基于三重指数串行的目标识别技术选取高相干点,同时提出一种不同于传统奇异值分解的时间序列分析算法。利用振幅离差指数、相干系数均值与强度值三重阈值串行的方案进行高相干点选取;通过阈值合理设定,不仅提高了监测结果的点位分布,也剔除了误选的点,保证了所选高相干点的质量;采用一种符合铁路边坡形变规律的线性模型作为约束条件,解决了时序分析过程中法方程秩亏的问题,并利用最小二乘反演得到了研究区域时间序列形变。实验表明,此方法提高了形变结果的精度和可靠性,证明了SBAS-InSAR技术在铁路边坡形变监测上具有良好的发展前景。     

南昌地铁沿线时序InSAR形变时空特征分析

基于32幅Sentinel-1 A影像数据,采用结合永久散射体(Persistent Scatterer,PS)特征点的小基线集雷达干涉测量技术获取了南昌市区2017年3月至2019年10月的地表形变信息,形变量级位于-22～14 mm/a.重点分析了各条地铁沿线形变的时空特征:1号线受地下水开采和南钢、洪钢漏斗的影响...     

Mexico City subsidence observed with persistent scatterer InSAR

We analyzed 23 satellite SAR (synthetic aperture radar) scenes using Persistent Scatter Interferometry (PSI) to study subsidence in Mexico City associated with groundwater withdrawal. The data were acquired by the Envisat ASAR system between January 2004 and July 2006. The spatial pattern of subsidence and the maximum subsidence rate (300 mm/year) are similar to earlier studies. Comparison to independent GPS data indicates RMS agreement between the two techniques of 6.9 mm/year, about the level expected based on joint data uncertainty. Significant annual variation in the GPS vertical data is not observed, suggesting minimal aquifer recharge during the rainy season, and justifying a simple linear model of phase variation through time for the PSI analysis.     

基于酉ESPRIT算法的极化干涉相位估计

目前SAR极化干涉测量地形参数已经成为一种新兴的前沿技术。在现有提取极化干涉相位的技术中,由空间谱估计理论发展而来的,利用MUSIC、TLS-ESPRIT算法获取干涉相位信息的方法正逐步完善起来。但由于SAR信号存在散射点的观测数据少的问题,利用上述方法往往不能得到更高精度的干涉相位。作者提出的基于酉ESPRIT算法估算干涉相位的方法,充分利用了复观测数据以及共轭数据中的信息,使得观测数据等效增加了一倍,从而提高了植被高度参数的估计精度。本文详细阐述了该方法的原理和实施步骤,并通过对SIR-C/X-SAR的L波段实际数据进行验证处理,表明酉ESPRIT算法十分有效。     

高分辨率PSI上海市沉降探测及分析

本文在改进的永久散射体(PS)探测方法基础上,应用高分辨率永久散射体雷达干涉(PSI)探测上海市地表沉降,并对沉降原因进行了详细分析。实验选取2008年4月至2010年1月间,由德国卫星TerraSAR-X(TSX)所获取的18幅X波段(波长为3.1 cm)高分辨率SAR影像为数据源,进行PS探测、PSI建模、形变提取和分析。实验结果表明,改进的PS探测方法探测出的PS点是合理和可靠的,且高分辨率SAR影像对地面硬目标识别能力较强,显著提高了PS点的密度和覆盖范围。沉降探测结果显示,最大相对沉降速率达30 mm/yr,平均沉降速率为11.5 mm/yr。     

PALSAR和ASARPSI显著地表沉降探测与分析

永久散射体雷达干涉(PSI)已被广泛应用于城市缓慢沉降监测,但针对显著性地表沉降监测及PSI适用性的探讨较少。本文选取天津市与廊坊市城郊结合部的典型工业化城镇为研究区,分别以2007至2010年间的23幅L波段(23.6 cm)ALOS PALSAR影像和2007至2009年间的23幅C波段(5.6 cm)ENVISAT ASAR影像为数据源,使用基于相位空间相关性分析的PSI方法进行时空沉降提取,并对两个平台的结果进行对比分析和交叉验证。在此基础上,结合长短波SAR对沉降敏感性不同的特征探讨该PSI方法应用于显著沉降解算的可靠性,并结合地质条件及地下水开采信息对实验区沉降的时空分布进行深入分析和解释。研究表明,两平台的沉降结果十分吻合,在沉降漏斗区二者均方根误差(RMSE)为6.5 mm/a;实验区地表沉降呈现出显著的非均匀性,最大沉降速率超过200 mm/a,造成严重沉降的主要原因为地下水的大量开采;证实了PSI方法在显著地表沉降监测方面的有效性和可靠性。     

Identifying natural and anthropogenically-induced geohazards from satellite ground motion and geospatial data: Stoke-on-Trent,UK

Determining the location and nature of hazardous ground motion resulting from natural and anthropogenic processes such as landslides, tectonic movement and mining is essential for hazard mitigation and sustainable resource use. Ground motion estimates from satellite ERS-1/2 persistent scatterer interferometry (PSI) were combined with geospatial data to identify areas of observed geohazards in Stoke-on-Trent, UK. This investigation was performed within the framework of the EC FP7-SPACE PanGeo project which aimed to provide free and open access to geohazard information for 52 urban areas across Europe. Geohazards identified within the city of Stoke-on-Trent and neighbouring rural areas are presented here alongside an examination of the PanGeo methodology.A total of 14 areas experiencing ground instability caused by natural and anthropogenic processes have been defined, covering 122.35 km². These are attributed to a range of geohazards, including landslides, ground dissolution, made ground and mining activities. The dominant geohazard (by area) is ground movement caused by post-mining groundwater recharge and mining-related subsidence (93.19% of total geohazard area), followed by landsliding (5.81%). Observed ground motions along the satellite line-of-sight reach maxima of +35.23 mm/yr and −22.57 mm/yr. A combination of uplift, subsidence and downslope movement is displayed.‘Construction sites’ and ‘continuous urban fabric’ (European Urban Atlas land use types) form the land uses most affected (by area) by ground motion and ‘discontinuous very low density urban fabric’ the least. Areas of ‘continuous urban fabric’ also show the highest average velocity towards the satellite (5.08 mm/yr) and the highest PS densities (1262.92 points/km²) along with one of the lowest standard deviations. Rural land uses tend to result in lower PS densities and higher standard deviations, a consequence of fewer suitable reflectors in these regions. PSI is also limited in its ability to identify especially rapid ground motion. As a consequence the supporting geospatial data proved especially useful for the identification of landslides and some areas of ground dissolution. The mapped areas of instability are also compared with modelled potential geohazards (the BGS GeoSure dataset).     

改进的PS探测方法及其应用

提出一种改进的永久散射体PS(Persistent Scatterer)探测方法,首先基于时序SAR影像的振幅信息,利用振幅和振幅离差指数双阈值法获取PS候选点,然后根据干涉相位空间相关性,对所有候选点进行相位稳定性分析,筛选出既满足雷达反射强度高、又符合散射稳定性要求的真实PS点,最后基于所选PS点提取形变信息。选取上海市局部区域作为实验区,以16幅TerraSAR-X(TSX)影像为数据源,进行PS探测和形变信息提取。结果表明,相比于已有的PS探测方法,本文方法能够更准确、可靠地识别出时序SAR影像中的PS点。形变结果显示,研究区域内最大沉降速率为-51mm/a,平均沉降速率为-15.8mm/a,以水准实测数据进行检核,验证了基于改进的PS探测方法进行地表形变信息提取结果的可靠性。     

Investigation of the ground displacement in Saint Petersburg,Russia, using multiple-track differential synthetic aperture radar interferometry

Global sea level rise and local land subsidence might exacerbate the risk of flooding in coastal plains. Among other cities, this is also the case for the high-latitude city of St. Petersburg, which has long been threatened by flood events. To protect the urban area from storm surges, the Union of Soviet Socialist Republics (USSR) in 1978 approved the construction of the 25 km long Flood Prevention Facility Complex (FPFC), which was completed in 2011. The risk of flooding in the city area of St. Petersburg is amplified by the fact that large sections of the coastal area have been reclaimed from the sea. In this study, we investigate the temporal evolution of the ground displacement in St. Petersburg. To this end, we perform an extended analysis based on the application of a simplified version of the differential interferometric synthetic aperture radar technique, known as the minimum acceleration (MinA) approach. The MinA algorithm is a multi-satellite/multi-track interferometric combination technique that allows working with multiple sets of SAR images. The method allowed generation of time series of two-dimensional (2-D) (i.e. East-West and Up-Down) deformation of the terrain by processing two sequences of Sentinel-1A/B (S-1A/B) SAR images acquired from 2016 to 2018, along the ascending and descending flight passes. The Small BAseline Subset (SBAS) algorithm was independently applied to the two sets of SAR data to generate the relevant Line-Of-Sight (LOS)-projected ground deformation time series. Subsequently, the LOS-projected deformation products were geocoded and jointly combined. The results indicate that the deformation in the city is predominantly vertical (i.e. it is subsiding) with a maximum subsidence rate of about 20 mm/year corresponding to the newly sea-reclaimed lands. Finally, the error budget of the retrieved 2-D deformation time series has also been addressed.     

The study on automatic registration of InSAR images

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.     

The study on automatic registration of InSAR images

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.     

基于ESPRIT算法的极化干涉SAR植被高度反演研究

由于存在着去相干分量,利用ESPRIT(旋转不变技术)算法对植被区域的极化干涉SAR(PollnSAR)数据进行反演的结果有较严重偏差.针对这一问题,结合极化干涉相干最优理论及其物理散射机制,引入新的散射矢量——相干最优化散射矢量,提出一种改进的基于ESPRIT的植被高度反算法.最后,利用欧空局(ESA)提供的模拟L波...