基于几何配准的多模式SAR影像配准及其误差分析

星载合成孔径雷达影像干涉处理时所需方位向配准精度因成像模式的差异而有所不同,目前在精密轨道条件下以几何配准为基础辅以影像信息的配准方案因其严格的理论模型和较高的精度成为干涉处理的首选。本文以TerraSAR-X影像为例,论证了不同成像模式影像所需的配准精度和卫星轨道精度,并通过理论分析和试验证明了精密轨道条件下,利用几何配准即可满足TerraSAR-X等卫星的条带模式影像干涉处理的需要;聚束模式影像需要在几何配准的基础上利用影像相干性或谱分集进一步优化配准结果。鉴于增强谱分集偏移量估计精度最高,本文进一步利用增强谱分集对比分析了不同轨道不同DEM条件下的几何配准误差。研究结果表明:卫星轨道切向误差是几何配准的主要误差源,目前常用3种DEM几何配准差异远小于0.001个像素,均可满足Sentinel-1影像干涉配准的需要。

Coregistration scheme and error analysis of multi-mode SAR image based on geometric coregistration

With the development of radar imaging technology and the diversification of imaging modes, the accuracy of coregistration in the direction of azimuth required by SAR interferometry is different. At present, due to the strict theoretical model and the high accuracy, the coregistration scheme with the image information based on geometric coregistration under the condition of precise orbits become the first choice for interference processing. In this paper, TerraSAR-X images have been taken as an example to demonstrate the accuracy of interferometric coregistration and satellite orbit required by different imaging modes. Furthermore, theoretical analysis and experimental validation have also been applied. It is proved that under the condition of precise orbits, SAR interferometric processing of strip-mode image of TerraSAR-X and other satellites can be achieved by geometric registration. While, spotlight imaging mode requires image coherence or spectral diversity to further optimization of the geometric coregistration results. Since the ESD (Enhanced Spectral Diversity) offset estimation method offers the highest accuracy. It has been used to estimate the geometric coregistration errors of Sentinel-1 satellite images with different orbit and DEM conditions. The results suggest that geometric coregistration error is mainly caused by the tangential error of the satellite orbit, and the difference of geometric corregistration of three kinds of DEM is much less than 0.001 pixels, which can meet the needs of Sentinel-1 image interference registration.