基于迪杰斯特拉算法的哨兵卫星TOPS模式时序影像精配准

Co-registration of Image Stacks for Sentinel-1A TOPS Mode Based on Dijkstra's Algorithm

  • 摘要: 目前,哨兵卫星被广泛应用于监测地表形变,然而其默认成像模式TOPS(terrain observation with progressive scanning)受粗配准的精度限制,方位向的频谱混叠会导致重叠观测区域出现相位跳变,需要通过精配准进行纠正。多数开源软件都采用几何配准和增强谱分集结合的方式对哨兵影像进行精配准。增强谱分集的精度通常受到时间去相干、几何去相干和方位向形变等诸多因素的影响,但其直接影响因素是相干性,研究了增强谱分集的精度与相干性的关系。同时,为了提高时序影像的配准精度,提出在精确估计相干性的基础上提取高相干点用于增强谱分集,并应用迪杰斯特拉最短路径算法生成最优配准像对,完成时序像对的精配准。利用传统的单主影像增强谱分集和目前精度最高的序贯网络增强谱分集(network-based enhanced spectral diversity,NESD)对所提出的方法进行了精度验证。实验证明,所提方法能够达到对哨兵影像进行有效精配准的目的,并且弥补了NESD方法的不足。

     

    Abstract: Today, Sentinel-1A data with terrain observation with progressive scanning (TOPS) imaging mode is increasingly used in earth observation aiming at consistent monitoring of surface change and its deformation. However, due to the limited accuracy of coarse co-registration, spectral aliasing along the azimuth direction enables the presence of phase jumping in overlapping area of neighboring bursts. Although geometrical co-registration in conjunction with enhanced spectral diversity (ESD) is proven to be a feasible strategy to correct such error and has been widely used in some open source softwares (e.g. DORIS (Delft object-oriented radar interferometric software), SNAP (sentinel applications platform), ISCE (InSAR scientific computing environment)), the performance of ESD is still not satisfactory and relies strongly on spatiotemporal decorrelation. Given that decorrelation is generally quantized by interferometric coherence, this paper presents and assesses a new methodology to improve the accuracy of ESD by fully exploring the high coherent targets. Specifically, this method focuses on mitigating the spatiotemporal decorrelation in fine co-registration procedures by:(1) Selecting stable targets with moderate and high coherence using accurate coherence estimation. (2) Maximizing coherence magnitude by optimal interferometric subset chosen from Dijkstra algorithm. We compare and test this method against current favorites based on single master image and network-based enhanced spectral diversity (NESD), and the experimental results demonstrate the value of our method. It can make up for the shortage of NESD method.

     

/

返回文章
返回