基于多尺度相关性分析的InSAR对流层延迟误差改正算法

针对合成孔径雷达干涉技术中对流层延迟误差会影响DEM精度的问题,提出采用小波多尺度相关性分析方法来减弱与高程相关的对流层延迟误差的影响,来提高合成孔径雷达干涉DEM的估计精度。该方法基于小波多分辨率分析理论,根据差分干涉相位不同组成的频率特性,利用小波分解重构均方根误差变化率确定分解层数,降低地形残差相位、噪声相位等对大气延迟误差相位估计的干扰,提取对流层延迟误差相位所在频带;然后结合对流层延迟误差相位和雷达坐标系下的DEM在不同尺度上的相关性定权并进行降权处理,重构解缠差分干涉图,改正差分干涉相位中与高程相关的对流层延迟的影响。采用本文方法对覆盖河南义马地区的2景ENVISAT ASAR数据进行处理,得到对流层延迟误差改正后的差分干涉图,估计的与高程相关的对流层延迟相位,与地形变化情况吻合。将对流层延迟误差改正后的干涉图用于DEM高程估计,结果显示本文方法重建的DEM与Aster GDEM的标准差由30.7 m提高到26.37 m,提高了InSAR DEM估计精度。

InSAR Tropospheric Delay Error Correction Algorithm based on Multi-Scale Correlation Analysis

Tropospheric delay error in synthetic aperture radar interferometry can affect DEM accuracy. This study adopts wavelet multi-scale correlation analysis to reduce the influence of tropospheric delay error on DEM estimation. This method is based on the wavelet multi-resolution analysis theory and the frequency characteristics of different components in differential interference phases. Firstly, the wavelet decomposition reconstruction RMS error rate is used to determine the decomposition layers. The terrain residual phase and noise phase are reduced to extract the frequency band where the troposphere delayed error phase is located. Secondly, we quantify the correlation between tropospheric delay error phase and DEM in radar coordinates and further down-weight the correlated coefficients. Lastly, the differential interferogram is reconstructed which reduces the influence of elevation-related tropospheric delay in InSAR. In this study, the ENVISAT ASAR data in Yima, Henan province are processed using the method proposed in this study. The differential interferogram with tropospheric delay error corrected are obtained to estimate elevation. The estimated tropospheric delay phase correlated with elevation is consistent with the topographic changes. Results show that the standard deviation of DEM error compared to Aster GDEM decreases from 30.7 m to 26.37 m, which indicates an increased accuracy of InSAR DEM.