基于SRTM DEM的InSAR高分辨率山区地表高程重建算法

摘要

山体的叠掩和阴影现象造成的信号去相关,一直是InSAR重建山区地表高程的瓶颈之一.为此,提出了一种新的基于粗分辨率SRTM DEM(约90m分辨率)辅助InSAR数据重建山区地表高程的方法.利用SRTM DEM模拟的干涉相位,对ERS-1/2干涉相位做去地形相位处理,得到残余相位.通过对解缠后的残余相位计算方差提取叠掩和阴影区域的噪声,并用平均相位近似恢复噪声区域的相位,然后将其转换为高程,并用SRTM DEM作高程补偿处理,从而实现地表高程重建.最后,定量比较了该方法与传统InSAR技术生成的DEM精度.实验表明,这种方法能有效提高传统InSAR技术生成地表高程的精度,这对提高星载雷达数据的使用效率具有重要意义.%Synthetic Aperture Radar Interferometric(InSAR)processing depends on phase unwrapping to convert phase to topographic height.However,in rugged terrain the signal decorrelation caused by layover and shadow is one of the limitations for InSAR topographic height reconstruction,because the phase unwrapping is difficult.A new algorithm is proposed in this paper to reconstruct high resolution digital elevation model(DEM)with the help of existing coarse SRTM DEM(about 90m×90m).Firstly,the simulated phase from coarse DEM is removed from the ERS-1/2interferogram.Thus the residual interferogram is easier for phase unwrapping.By calculating the variance of unwrapped residual interferogram,a proper threshold is selected to extract the noise phase of layover and shadow,and then the noise area are substituted by surrounding average phase to recover the phase approximately.After converting the residual phase to height.SRTM DEM is added to reconstruct the topographic height.The result shows that this method can not only solve the problem of phase unwrapping for layover and shadow in rugged terrain.but also improve the height accuracy and topographic detail feature of coarse resolution DEM.