一种面向无参考点的顺轨干涉SAR海面复图像配准方法

A Coregistration Method for Ocean Surface Complex Images of Along-track Interferometric SAR without Control Point

顺轨干涉SAR海面复图像通常利用静止陆地参考点进行配准,获得精确有效的海洋流场干涉相位信息。复图像中无参考点时,仅能依据海浪纹理进行配准,受海面随机运动以及低信噪比的影响,配准像素偏移往往会出现像素级误差,并导致干涉相位图质量严重下降。根据大尺度海浪变化周期较长,在干涉成像间隔内可视作静止这一特征,该文提出保留大尺度海浪对应的方位谱分量以提高数据信噪比和相关性,进而提高配准精度的方法,并选用海面实际方位分辨率作为大尺度海浪方位谱选取范围的约束条件。通过机载顺轨干涉SAR实验数据证明,所提方法可有效提高无参考点海面复图像的配准精度。

In order to get high-precision interferogram of ocean surface current, static control points from land area are normally used to coregistrate ocean surface complex images of along-track interferometric SAR. When there is no control point in the image, ocean wave texture can only be used instead. Under the influence of stochastic movement and low signal-to-noise ratio of the ocean, the coregistration error tends to exceed one pixel, hence damages the quality of interferogram severely. Since the period of large-scale wave is much longer than the interferometric interval, large-scale wave can be treated as static during the interval. Based on this matter of fact, this paper proposes a coregistration method by reserving the spectrum of large-scale wave to improve the signal-to-noise ratio and correlation coefficient, further improving the coregistration precision. Ocean azimuth resolution is used as the criterion to decide which part of the spectrum should be reserved. Airborne along-track interferometric SAR data is demonstrated here, proving the proposed method can improve the coregistration precision of ocean surface complex images without control point.