基于点目标的机载SAR极化定标算法研究
发布时间：2018-08-12 18:10
【摘要】：随着极化合成孔径雷达(PolSAR)技术的发展,极化SAR数据被广泛地应用于地物分类、土地利用、地表参数反演等方面,而极化定标技术是对极化SAR数据进行分析和应用的前提。由于受到雷达天线不同的极化通道之间不能完全隔离等因素的影响,导致测量的极化SAR数据包含有失真,不能准确地表征地物的后向散射特性。因此必须对SAR数据进行极化定标,精确校正不同极化通道之间的相对幅度和相位,以期准确地提取存在于不同极化组合的幅度和相位中的地物信息,凸显极化SAR系统的优势。针对极化定标技术,国内外学者开展了大量的科学研究,其研究工作可分为以下三种类型:(1)基于点目标的极化定标算法;(2)基于面目标的定标算法;(3)基于点目标和面目标相混合的定标算法。本文主要针对基于点目标的极化定标算法开展相关研究,该类型定标方法的基本思路为:首先提取SAR图像中散射矩阵已知的点目标;然后构建点目标的测量值及其理论值,两者之间的矩阵方程,进而推算极化定标参数;最后将所求的定标参数应用到其他未知区域,得到极化定标后的SAR数据。基于现有极化定标算法的不足,本文提出了两种基于点目标的极化定标算法,其主要的研究工作如下:(1)介绍了极化SAR的数据基础,叙述了常用极化定标模型及典型极化定标算法,总结了影响极化定标精度的两大因素:飞行平台的不稳定性及点目标的摆放偏差,其中飞行平台不稳定性包括6个姿态参数—俯仰角、横滚角、偏航角、距离向偏移、方位向偏移、高程向偏移;点目标的摆放偏差主要是指点目标在垂直于雷达视线的平面内绕雷达视线所产生的旋转偏差。(2)对现有的基于点目标的Whitt算法与基于点目标和面目标相混合的Ainsworth算法等典型极化定标算法进行了分析和研究,针对算法中的不足之处,如算法中所作出的假设条件,本文提出了一种无约束的基于点目标的极化定标算法。利用所提算法分别对模拟数据和2014年在海南南部地区获取的机载SAR全极化C波段数据进行极化定标实验,验证了算法的性能。与Whitt算法、Ainsworth算法等典型算法相比,该算法没有作出地物散射互异性等假设条件,克服了算法中的不足。(3)在对Whitt定标算法和Ainsworth定标算法研究的基础上,鉴于典型极化定标算法的推导过程较为复杂等问题,本文提出了一种推导过程较为简单的基于点目标的极化定标算法,以校正不同极化通道间在幅度和相位上的畸变。并分别通过实际的机载SAR全极化C波段数据和模拟数据对该方法的有效性进行了检验。同其他方法相比,该方法简化了极化定标参数的求解步骤,使得求解过程简单,易于理解。
[Abstract]:With the development of polarimetric synthetic aperture radar (PolSAR) technology, polarimetric SAR data are widely used in the classification of ground objects, land use, surface parameters inversion and so on. The polarimetric calibration technique is the prerequisite for the analysis and application of polarimetric SAR data. Due to the fact that different polarization channels of radar antenna can not be completely isolated, the measured polarized SAR data packet contains distortion and can not accurately characterize the backscattering characteristics of ground objects. Therefore, it is necessary to calibrate the polarization of SAR data and correct the relative amplitude and phase between different polarization channels accurately, in order to extract the information of ground objects in different polarization combinations accurately, and highlight the advantages of polarized SAR system. For the polarization calibration technology, scholars at home and abroad have carried out a lot of scientific research. The research work can be divided into the following three types: (1) polarization calibration algorithm based on point target; (2) calibration algorithm based on surface target; (3) calibration algorithm based on mixture of point target and surface target. This paper mainly focuses on the research of polarization calibration algorithm based on point target. The basic idea of this kind of calibration method is as follows: firstly, the point target whose scattering matrix is known in SAR image is extracted; then, the measured value of point target and its theoretical value are constructed. The matrix equation between the two is used to calculate the polarization calibration parameters, and finally, the SAR data after polarization calibration are obtained by applying the obtained calibration parameters to other unknown regions. In this paper, two polarization calibration algorithms based on point target are proposed. The main research work is as follows: (1) the data base of polarized SAR is introduced. The commonly used polarization calibration models and typical polarization calibration algorithms are described. Two major factors that affect the precision of polarization calibration are summarized: the instability of the flight platform and the deviation of the point targets. The instability of flight platform includes six attitude parameters, such as pitch angle, roll angle, yaw angle, distance migration, azimuth migration and elevation migration. The positioning deviation of point target is mainly the rotation deviation caused by pointing point target in the plane perpendicular to radar line of sight. (2) the existing Whitt algorithm based on point target and the Ainsworth calculation based on point target and surface target are calculated. Some typical polarization calibration algorithms, such as the proposed method, are analyzed and studied. In view of the shortcomings of the algorithm, such as the assumptions made in the algorithm, this paper proposes an unconstrained polarization calibration algorithm based on point targets. The proposed algorithm is used to verify the performance of the proposed algorithm by polarization calibration experiments on the simulated data and the airborne SAR fully polarized C-band data obtained in southern Hainan in 2014. Compared with some typical algorithms such as Whitt algorithm, the algorithm does not make assumptions such as mutual heterogeneity of ground scattering, which overcomes the shortcomings of the algorithm. (3) based on the research of Whitt calibration algorithm and Ainsworth calibration algorithm, In view of the complexity of the derivation process of typical polarization calibration algorithm, a simple polarization calibration algorithm based on point target is proposed to correct the distortion in amplitude and phase between different polarization channels. The validity of the method is verified by actual airborne SAR full polarization C-band data and simulated data. Compared with other methods, this method simplifies the calculation of polarization calibration parameters, makes the solution process simple and easy to understand.
【学位授予单位】：山东科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P237
本文编号：2179878
[Abstract]:With the development of polarimetric synthetic aperture radar (PolSAR) technology, polarimetric SAR data are widely used in the classification of ground objects, land use, surface parameters inversion and so on. The polarimetric calibration technique is the prerequisite for the analysis and application of polarimetric SAR data. Due to the fact that different polarization channels of radar antenna can not be completely isolated, the measured polarized SAR data packet contains distortion and can not accurately characterize the backscattering characteristics of ground objects. Therefore, it is necessary to calibrate the polarization of SAR data and correct the relative amplitude and phase between different polarization channels accurately, in order to extract the information of ground objects in different polarization combinations accurately, and highlight the advantages of polarized SAR system. For the polarization calibration technology, scholars at home and abroad have carried out a lot of scientific research. The research work can be divided into the following three types: (1) polarization calibration algorithm based on point target; (2) calibration algorithm based on surface target; (3) calibration algorithm based on mixture of point target and surface target. This paper mainly focuses on the research of polarization calibration algorithm based on point target. The basic idea of this kind of calibration method is as follows: firstly, the point target whose scattering matrix is known in SAR image is extracted; then, the measured value of point target and its theoretical value are constructed. The matrix equation between the two is used to calculate the polarization calibration parameters, and finally, the SAR data after polarization calibration are obtained by applying the obtained calibration parameters to other unknown regions. In this paper, two polarization calibration algorithms based on point target are proposed. The main research work is as follows: (1) the data base of polarized SAR is introduced. The commonly used polarization calibration models and typical polarization calibration algorithms are described. Two major factors that affect the precision of polarization calibration are summarized: the instability of the flight platform and the deviation of the point targets. The instability of flight platform includes six attitude parameters, such as pitch angle, roll angle, yaw angle, distance migration, azimuth migration and elevation migration. The positioning deviation of point target is mainly the rotation deviation caused by pointing point target in the plane perpendicular to radar line of sight. (2) the existing Whitt algorithm based on point target and the Ainsworth calculation based on point target and surface target are calculated. Some typical polarization calibration algorithms, such as the proposed method, are analyzed and studied. In view of the shortcomings of the algorithm, such as the assumptions made in the algorithm, this paper proposes an unconstrained polarization calibration algorithm based on point targets. The proposed algorithm is used to verify the performance of the proposed algorithm by polarization calibration experiments on the simulated data and the airborne SAR fully polarized C-band data obtained in southern Hainan in 2014. Compared with some typical algorithms such as Whitt algorithm, the algorithm does not make assumptions such as mutual heterogeneity of ground scattering, which overcomes the shortcomings of the algorithm. (3) based on the research of Whitt calibration algorithm and Ainsworth calibration algorithm, In view of the complexity of the derivation process of typical polarization calibration algorithm, a simple polarization calibration algorithm based on point target is proposed to correct the distortion in amplitude and phase between different polarization channels. The validity of the method is verified by actual airborne SAR full polarization C-band data and simulated data. Compared with other methods, this method simplifies the calculation of polarization calibration parameters, makes the solution process simple and easy to understand.
【学位授予单位】：山东科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P237
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1 张林涛;洪峻;明峰;王珂;;基于点目标的机载SAR极化定标改进算法[J];电子测量技术;2011年03期
相关硕士学位论文 前1条
1 魏茉;基于热带雨林的星载极化SAR定标方案研究[D];中国科学院研究生院（空间科学与应用研究中心）;2007年
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