机载SAR影像定向中像点粗差的拟准检定方法

结合距离-多普勒模型,推导了SAR(synthetic aperture radar)影像定向中像点坐标粗差对误差方程的影响,分析了像点坐标粗差探测的必要性和难点;依据粗差的拟准检定法,针对SAR影像定向中的像点坐标粗差检定问题,设计了具体的解算流程和策略,首次将粗差的拟准检定法运用到机载SAR影像定向中。并分别利用模拟和实测数据进行了系统性的实验,结果表明,该方法不仅能够准确探测出多个粗差的位置,而且能够估计出粗差的大小。与SAR影像定向通常采用的最小二乘方法相比,该方法能够明显提高SAR影像定向参数的解算精度以及后续的立体定位精度,对于修复受粗差影响的SAR影像数据具有重要意义。

Quasi-Accurate Detection of Image Coordinate Gross Error for Airborne SAR Images Orientation

This paper focuses on the detection of gross error in airborne SAR image coordinates during the process of orientation parameter calculation and stereo positioning. Firstly, based on the range Doppler model, a preliminary discussion is conducted to investigate the impact of image coordinate gross error on the error equations. Secondly, after analyzing the necessity and difficulty of gross detection, based on the quasi-accurate detection, a specific calculation scheme and strategy for orientation parameter calculation is proposed. For the first time, quasi-accurate detection is applied to SAR image orientation. Finally, a series of experiments with both simulated data and real airborne SAR images are carried out to validate the proposed scheme and strategy. The experimental results show that the proposed scheme in this paper is able to detect and calculate the gross errors in image coordinates. Compared to the classical least-square estimation usually used in image orientation, a higher accuracy of both orientation parameters and the subsequent stereo positioning are achieved. The research in this paper is particularly meaningful to improve the quality of the SAR data affected by gross errors in situations where control points are not enough.