采用螺旋散射的SAR极化定标参考地物提取方法

Distributed Targets Extraction for SAR Polarimetric Calibration Using Helix Scattering

极化合成孔径雷达观测系统获取的影像需要经过极化定标处理才能进行定量的分析与应用。当前的极化定标方案普遍采用分布式地物解算串扰和交叉极化通道不平衡误差,需要在定标前选取满足一定散射特征的分布式地物作为定标参考样本。利用螺旋散射的极化特征与分布特点,提出了一种新的极化定标参考地物自动提取方法。该方法根据极化目标分解构建螺旋散射比率特征,并采用自适应阈值分割方法自动提取地物样本。采用C波段机载极化雷达影像进行实验,结果表明,所提方法能够保持影像极化定标的准确性,并能提高极化定标的精度。

Polarimetric SAR technology is widely used in remote sensing and earth observation. Before any quantitative research or application are carried out, polarimetric calibration must be applied on the acquired images. The current polarimetric calibration schemes generally use distributed targets to solve crosstalk and cross-polarization channel imbalance errors. Therefore, it is necessary to extract the distributed targets that satisfy certain scattering characteristics before calibration. In this paper, we propose an automatic method of reference samples extraction for polarimetric calibration, by exploiting the polarization and distribution characteristics of helix scattering. According to the polarization target decomposition, we constructe a helix scattering ratio feature, and adaptive threshold segmentation method is also used to extract the reference samples automatically. A C-band airborne polarimetric SAR image from the Institute of Electronics, Chinese Academy of Sciences is tested. The results show that this method can maintain the correctness of polarimetric calibration, and can improve the calibration accuracy comparing with the algorithms based on polarimetric correlation coefficient or scattering power.