基于时变多项式的InSAR轨道误差去除和DEM估计

Modeling for InSAR orbit error based on time-varying polynomials to estimate DEM

针对现有数字高程模型的更新生产模式难以满足实景三维、智慧城市信息化建设的迫切需求,InSAR重轨技术通过短周期重返有望实现快速、大范围、高精度的DEM估计。然而,在重轨模式下,两景SAR影像的轨道误差难以通过干涉过程抵消,严重的时变轨道误差难以满足高精度测图的需求。因此,利用重轨InSAR技术获取DEM的关键在于去除轨道误差的影响。鉴于此,本文提出了一种基于时变多项式模型估计轨道误差的方法,该模型分块构建时频基线和轨道误差之间的函数关系,并利用加权最小二乘实现轨道误差的稳健估计;首次使用我国L波段InSAR数据在湖南省境内获取的数据进行了测试,并估计了InSAR DEM,试验结果验证了该方法的有效性和稳健性;利用星载ICESat-2数据验证了该方法估计DEM的精度,两试验区的RMSE分别为4.58、6.44 m,相比于传统轨道误差去除和DEM估计的方法(8.94、13.68 m)分别提高了48.8%、52.9%。

The existing digital elevation model update production mode is difficult to meet the urgent needs of real-life 3D and smart city information construction.InSAR repeat-pass technology is expected to achieve fast,large-scale,and high-precision DEM estimation through short-cycle revisit.However,in the repeat-pass mode,the severe time-varying orbital error is difficult to meet the requirements of high-precision mapping because the orbital error of the two SAR images is difficult to be offset by the interferometric process.Therefore,one of the key points of using repeat-pass InSAR technology to estimate DEM is how to reduce the influence of orbital error.Based on this,this paper proposes a method for estimating orbital error based on a time-varying polynomial model.This model constructs the functional relationship between the time-frequency baseline and the orbital error by block construction,and uses weighted least squares to achieve robust estimation.In order to verify the effectiveness of the proposed method,the data of L-band InSAR data in Hunan province are used for the first time to conduct tests,and InSAR DEM is estimated.In the two test sites,the experimental results verified the effectiveness and robustness of the proposed method and estimated the orbital error well.In addition,the accuracy of the DEM estimated by the proposed method is verified using satellite ICESat-2 data.The RMSE of the two test areas are 4.58 and 6.44 m,respectively,which are 48.8%and 52.9%higher than the traditional satellite method of removing orbital error to estimate DEM(8.94 and 13.68 m).