基于地形辅助的无人机载InSAR图像分区配准方法

Topography-assisted UAV InSAR Image Registration Method with Image Partition

小型化、轻量化的无人机(UAV)为合成孔径雷达(SAR)提供了更加灵活、机动的观测平台,无人机载干涉SAR(InSAR)逐步应用于干涉测量领域。无人机小而轻,易受气流扰动的影响,采用多航过模式进行干涉测量时,飞行航迹非线性且不平行。非线性、不平行的飞行轨迹导致两幅图像之间存在几何畸变。在复杂地形条件下,无人机载InSAR的干涉图像对之间的偏移量大且具有明显的空变特性,给图像配准带来了很大的技术挑战,常规的基于多项式拟合的配准方法不再适用。该文提出了一种利用地形辅助分区的图像配准方法。首先基于航迹信息生成高程门限,利用外部地形对测量区域进行图像分区处理,然后对区域内的偏移量构建多项式变换模型,对各区域边界处的偏移量施加约束,并进行联合求解,最后获得连续的全局偏移量拟合面,通过对辅图像进行重采样实现精配准。基于P波段无人机载InSAR获取的实测数据,初步验证了该方法的有效性。

Miniaturized and lightweight Unmanned Aerial Vehicles(UAV)provide a flexible platform for Synthetic Aperture Radar(SAR).The application of UAV Interferometric SAR(InSAR)is gradually increasing in interferometric measurement fields.UAVs are small and light,which are easily affected by airflow disturbances.Their trajectories are nonlinear and unparallel when adopting the multipass mode for interferometry.The nonlinear and unparallel trajectories result in geometric distortion between the interferometric image pairs.Under complex topography conditions,the interferometric image pairs of UAVs have large offsets that are obviously space-dependent,thereby resulting in substantial technical challenges during image registration.Conventional image registration methods based on polynomial fitting are no longer applicable.In this study,we proposed an image registration method based on image partition with topography assistance.First,an elevation threshold is generated based on the UAV trajectories,and the measurement area is partitioned using the assisted topography.Then,a polynomial fitting model is constructed for offsets within each partition with constraints applied at the partition boundaries for joint optimization.Finally,continuous global offset fitting surfaces are obtained,and precise image registration is achieved by resampling the slave image.The effectiveness of the proposed method is preliminarily validated using real measurement data obtained from UAV InSAR in the P-band.