基于StereoSAR辅助的InSAR DEM重建方法研究

StereoSAR与InSAR是两种利用合成孔径雷达图像重建DEM的关键技术。InSAR利用SAR干涉像对的相位信息重建高程,具有DEM重建精度高的特点,但DEM重建精度受环境、时间等失相干因素影响较大;StereoSAR是利用SAR立体像对的幅度信息重建高程,尽管DEM重建理论精度比InSAR差,但受失相干因素影响小,并且可以在缺乏外部辅助高程信息时获取绝对DEM。在传统的InSAR处理中,干涉条纹密集区域相位解缠难度较大,存在相位解缠错误和错误传播现象,且在没有地面控制点或外部DEM的时难以获得绝对DEM。文中提出了一种迭代式的基于StereoSAR辅助的InSAR高精度DEM重建方法,该方法可以在缺乏外部高程信息时获得绝对DEM,降低干涉条纹密集区域相位解缠的难度,提高DEM重建精度。采用文中所提方法、传统InSAR方法及公开DEM辅助InSAR DEM重建方法,分别在地形复杂与平坦区域进行DEM重建,并用ICESat/GLAS及TanDEM-X DEM进行精度评估。DEM重建结果验证了文中所提方法的有效性,所提方法的DEM重建精度优于传统InSAR方法且与公开DEM辅助InSAR DEM重建方法精度相当。

InSAR DEM Reconstruction Method Based on StereoSAR

StereoSAR and InSAR are two key techniques for DEM reconstruction by using synthetic aperture radar images. In In-SAR processing, the phase of the SAR images is used to reconstruct the elevation. It has the characteristics of high DEM reconstruction accuracy. However, the accuracy of DEM reconstruction is greatly affected by incoherent factors such as environment or time; The amplitude of SAR stereo image pairs is used to reconstruct the elevation in StereoSAR processing. Although the theoretical accuracy of DEM reconstruction is worse than InSAR, the accuracy of DEM reconstruction is less affected by incoherent factors, and the absolute DEM can be obtained directly in StereoSAR processing when the external auxiliary elevation is not available. In the traditional InSAR processing, the phase unwrapping is difficult in the interference fringe dense region, there are phase unwrapping errors and errors propagation, and it is difficult to obtain absolute DEM in the absence of ground control points or external DEM. In this paper, a InSAR high-precision DEM reconstruction iterative method based on StereoSAR is designed. This method can achieve absolute DEM in the absence of external elevation, reduce the difficulty of phase unwrapping and improve the DEM reconstruction accuracy. In this paper, the proposed method, the traditional InSAR method and the public DEM-assisted InSAR DEM reconstruction method are used to reconstruct DEM in complex and flat terrain areas respectively, and the accuracy is evaluated by ICESat/ GLAS and TanDEM-X DEM. The DEM reconstruction results verify the effectiveness of the proposed method. The DEM reconstruction accuracy of the proposed method is better than that of the traditional InSAR method and is comparable to that of the public DEM-assisted InSAR DEM reconstruction method.