永久散射体雷达干涉(PSI)技术及其应用于区域地表形变监测已成为雷达遥感领域的研究热点之一.使用单一卫星平台所获取的单侧视SAR影像时间序列进行PSI分析,仅能获取沿雷达视线(LOS)方向的一维地表位移信息.本文提出了基于多平台永久散射体雷达干涉提取三维地表形变速度场的模型与算法,其基本策略是:首先针对每一卫星平台的SAR影像时间序列进行PSI分析,并计算各地面目标沿LOS向的位移速度值,然后联合各平台所对应的LOS向位移速度值进行建模,并基于最小二乘方法解算各地面目标的三维位移速度分量.实验选取天津市西北部作为测试区,使用2007—2010年所获取的39幅TerraSAR-X影像、23幅ENVISAT ASAR影像和16幅ALOS PALSAR影像进行分析,经联合解算得到了该测试区域的垂直位移速度场以及南北向和东西向水平位移速度分量.与地面水准和已有GPS观测结果对比分析表明:多平台PSI的垂直位移速度场精度可达毫米级,而其水平位移速度分量与已有GPS结果基本一致.多平台PSI分析无需引入任何外部形变参考信息,便可以实现形变场的偏差校准和三维形变场的恢复.
Research on persistent scatterer radar interferometry(PSI) and its application to regional deformation monitoring has become one of the focused topics in the radar remote sensing community.PSI analysis with time series of SAR images collected by a single side-looking mode from a single satellite platform can only reveal one-dimensional(1D) ground deformation along radar line of sight(LOS).This paper proposes the model and algorithm for extracting the three-dimensional(3D) deformation velocity field using a multi-platform PSI method.Its basic strategy includes two parts.The SAR images collected by each single platform are first used to estimate the LOS deformation velocity field by PSI analysis,and then all the 1D deformation velocity fields obtained from different platforms are combined to resolve the 3D deformation velocity field by least squares solution.For validation purpose,the northwestern part of Tianjin(China) is selected as the testing area,and 39 TerraSAR-X images,23 ENVISAT ASAR and 16 ALOS PALSAR images collected over this area between 2007 and 2010 are used to estimate the vertical deformation velocity field and the horizontal deformation velocities.Comparison with the ground-based leveling results and the existing GPS measurements indicates that the vertical deformation velocities derived by the combined solutions can reach a millimeter accuracy level,and the horizontal deformation velocities are in good agreement with those derived from GPS data analysis.The multi-platform PSI analysis can be used to calibrate the 1D deformation velocity field and to reconstruct the 3D deformation velocity field.