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提出一种结合子孔径相关测度的时序高相干点探测方法,首先对时序SAR影像进行谱分解获得子孔径视图,通过时序子孔径相关测度进行强散射点筛选,然后分别根据振幅离差和干涉相位空间相关性,对目标点进行相位稳定性分析,探测出既满足强散射且在时间序列上散射稳定的高相干点。利用改进的点探测方法和短基线INSAR技术,对北京2003—2009年间40景ASAR影像进行相位建模,获取地面沉降时空分布特征,分析典型地物时序沉降过程,研究北京地面沉降与地下水开采关系。结果表明:相比已有方法,本文结合子孔径相关测度的高相干点探测结果更准确可靠;利用本文点探测方法反演的历史累积沉降信息,与水准结果一致,平均速率之差在3.69 mm/a以内,中误差为1.36 mm/a;研究区地面沉降最大速率达92.25 mm/a,空间不均匀分布明显,地面沉降量与地下水开采量呈分段的非线性相关。
This paper proposes a time-dependent coherence point detection method based on correlation measure of sub-aperture. Firstly, the sub-aperture view is obtained by spectral decomposition of time-lapse SAR image, and the strong scatter point is screened by time-dependent sub-aperture correlation measure. Spatial correlation, phase stability of the target point of analysis, to detect not only meet the strong scattering and scattering in the time series of high coherence point. By using the improved point detection method and short-baseline INSAR technique, the ASIM imaging of 40 scenes in Beijing during 2003-2009 was modeled, the temporal and spatial distribution characteristics of land subsidence were obtained, and the time series of typical landform subsidence was analyzed to study the relationship between Beijing land subsidence and groundwater exploitation . The results show that compared with the existing methods, the detection results of high coherence points based on sub-aperture correlation measure are more accurate and reliable. The historical cumulative settlement information retrieved by this point detection method is consistent with the level results. The difference of average velocity is 3.69 mm / a, the error is 1.36 mm / a; the maximum rate of land subsidence in the study area is 92.25 mm / a, the spatial heterogeneity is obvious, and the subsidence of ground subsidence is related to the subsection nonlinearity.