机载SAR图像方位向几何畸变研究

由于大气干扰等原因，SAR平台很难按照理想航迹飞行，造成了SAR图像的散焦和几何畸变。这些几何畸变主要发生在方位向上，因此SAR图像方位向几何畸变校正对于SAR图像应用具有很重要的意义。本文分析了非理想轨迹对SAR图像方位向几何畸变的影响，对常见的视线误差进行了建模。根据距离建模方法，将视线误差建模为加速模型和正弦模型，并对正弦模型进行了重点分析，推导了它的正交多项式展开，得到了正弦变化模型下方位向几何畸变的预测表达式及校正相位。最后通过仿真试验和实测数据处理结果验证了文中算法的有效性。 

The Research on Azimuth Geometric Distortion of Airborne SAR Image

It is difficult for SAR to fly as the nominal line because of atmosphere turbulence etc. As a result, the defocus and geometric distortion appears in SAR image, which mainly happens on the azimuth. So, the elimination of azimuth geometric distortion of SAR image plays an important role in SAR image application. This paper analyzes the influence of trajectory deviations to the azimuth geometric distortion of SAR image, and builds the model of the familiar error in line of sight. The accelerating model and sine model are build according to the model of range. The paper discusses the sine model in more detail, and deduces its orthogonal polynomial spread, getting its prediction expression and rectifying phase of azimuth geometric distortion. In the end, the results of the simulation and real SAR data processing testify the algorithm’s validity.