基于點目標的機載SAR極化定標算法研究
發(fā)布時間：2018-08-12 18:10
【摘要】：隨著極化合成孔徑雷達(PolSAR)技術(shù)的發(fā)展,極化SAR數(shù)據(jù)被廣泛地應用于地物分類、土地利用、地表參數(shù)反演等方面,而極化定標技術(shù)是對極化SAR數(shù)據(jù)進行分析和應用的前提。由于受到雷達天線不同的極化通道之間不能完全隔離等因素的影響,導致測量的極化SAR數(shù)據(jù)包含有失真,不能準確地表征地物的后向散射特性。因此必須對SAR數(shù)據(jù)進行極化定標,精確校正不同極化通道之間的相對幅度和相位,以期準確地提取存在于不同極化組合的幅度和相位中的地物信息,凸顯極化SAR系統(tǒng)的優(yōu)勢。針對極化定標技術(shù),國內(nèi)外學者開展了大量的科學研究,其研究工作可分為以下三種類型:(1)基于點目標的極化定標算法;(2)基于面目標的定標算法;(3)基于點目標和面目標相混合的定標算法。本文主要針對基于點目標的極化定標算法開展相關(guān)研究,該類型定標方法的基本思路為:首先提取SAR圖像中散射矩陣已知的點目標;然后構(gòu)建點目標的測量值及其理論值,兩者之間的矩陣方程,進而推算極化定標參數(shù);最后將所求的定標參數(shù)應用到其他未知區(qū)域,得到極化定標后的SAR數(shù)據(jù)�；诂F(xiàn)有極化定標算法的不足,本文提出了兩種基于點目標的極化定標算法,其主要的研究工作如下:(1)介紹了極化SAR的數(shù)據(jù)基礎,敘述了常用極化定標模型及典型極化定標算法,總結(jié)了影響極化定標精度的兩大因素:飛行平臺的不穩(wěn)定性及點目標的擺放偏差,其中飛行平臺不穩(wěn)定性包括6個姿態(tài)參數(shù)—俯仰角、橫滾角、偏航角、距離向偏移、方位向偏移、高程向偏移;點目標的擺放偏差主要是指點目標在垂直于雷達視線的平面內(nèi)繞雷達視線所產(chǎn)生的旋轉(zhuǎn)偏差。(2)對現(xiàn)有的基于點目標的Whitt算法與基于點目標和面目標相混合的Ainsworth算法等典型極化定標算法進行了分析和研究,針對算法中的不足之處,如算法中所作出的假設條件,本文提出了一種無約束的基于點目標的極化定標算法。利用所提算法分別對模擬數(shù)據(jù)和2014年在海南南部地區(qū)獲取的機載SAR全極化C波段數(shù)據(jù)進行極化定標實驗,驗證了算法的性能。與Whitt算法、Ainsworth算法等典型算法相比,該算法沒有作出地物散射互異性等假設條件,克服了算法中的不足。(3)在對Whitt定標算法和Ainsworth定標算法研究的基礎上,鑒于典型極化定標算法的推導過程較為復雜等問題,本文提出了一種推導過程較為簡單的基于點目標的極化定標算法,以校正不同極化通道間在幅度和相位上的畸變。并分別通過實際的機載SAR全極化C波段數(shù)據(jù)和模擬數(shù)據(jù)對該方法的有效性進行了檢驗。同其他方法相比,該方法簡化了極化定標參數(shù)的求解步驟,使得求解過程簡單,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.
【學位授予單位】：山東科技大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：P237
本文編號：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.
【學位授予單位】：山東科技大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：P237
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相關(guān)碩士學位論文 前1條
1 魏茉;基于熱帶雨林的星載極化SAR定標方案研究[D];中國科學院研究生院（空間科學與應用研究中心）;2007年
，本文編號：2179878
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