小麦的电磁散射回波响应系统研究及仿真系统软件

发布时间：2018-06-15 08:13

本文选题：小麦 + 微波遥感　；参考：《宁夏大学》2017年硕士论文

【摘要】：小麦不仅是三大谷物之一,更是我国的主要粮食作物之一。因此,只有能够对小麦种植面积进行精确的估算并且可以监测生长过程中的病虫害,才能更好的提高农作物产量。目前来看,通过使用微波遥感技术来勘测农作物已经获取了很大的成绩。光学遥感在这个领域虽然运用的较早,数据也更方便获得,可是它容易受天气的干扰,导致了光学遥感在监测植被时获取到的数据不精确。而微波遥感技术不但可以全天候、全天时的进行监控测量,还能够穿过植被,这些优点不仅补足了光学遥感的缺点,还直接推进了微波遥感在农业的发展。本文以农作物——小麦为研究对象,研究极化干涉SAR对随机粗糙面上小麦的电磁散射机理并构建小麦的电磁散射回波响应系统软件。首先,在使用Pol-InSAR对信号进行处理的过程中,先对区域地点进行勘测获取图像复数据信息,将两副SAR影像的数据信息按照图像配准、滤波、干涉处理、相位解缠以及数字高程反演等过程进行研究,最后得到所勘测区域的三维坐标。将雷达数据快速可视化,就能够获得对应的数字高程信息。由于相位解缠的好坏决定了数字高程的准确性,于是本文将几种相位解缠方法进行对比,为用户及时提供信息以便于最终达到监测小麦长势的目的。随后,研究随机粗糙面的入射角与后向散射系数的关系并完成了仿真。其中,对小麦进行了抽象描述并构建物理模型,可以清楚的看到小麦的入射角和后向散射系数变化的关系。经过对小麦模型的构建,研究并得到小麦的极化特性和相关特性,从而建立小麦入射角和后向散射系数之间的关系,为小麦生物物理参数的微波遥感定量反演奠定基础。本文的主要工作内容如下:1.介绍了 Pol-InSAR处理信号的具体过程及步骤。分别读取主辅SAR图像数据,对图像进行影像配准、干涉图生成、噪声滤波、相位解缠等处理,最终可以得到三维数字高程模型重建。2.研究了随机粗糙面的建模方法,对其中的部分方法进行简单阐述,其中,主要对经典的Kirchhoff近似理论和改进积分方程法(AIEM)进行详细说明,并在文中重点提出统计拓展改进积分方程法(SEAIEM)算法。3.将小麦抽象成物理模型,小麦叶、茎、秆分别抽象成盘状、针状及有限长圆柱,并且使用广义瑞利金斯计算求得物理模型与后向散射系数之间的关系,为下一步小麦的整体建模构建理论基础。4.将随机粗糙面和小麦的物理模型进行相干叠加后,可以重构小麦的整体模型,通过选择小麦及粗糙面的参数,能够比较准确地得到小麦微波后向散射系数随入射角变化而变化的关系,为后期小麦的生物量反演做理论基础。5.对以上研究内容进行MATLAB GUI界面设计,构建小麦的电磁散射回波响应系统软件。
[Abstract]:Wheat is not only one of the three cereals, but also one of the main food crops in China. Therefore, only by accurately estimating the planting area of wheat and monitoring the diseases and pests in the growth process, can the crop yield be improved better. At present, the use of microwave remote sensing technology to survey crops has made great achievements. Although optical remote sensing has been used in this field earlier and the data are more convenient to obtain, it is easy to be disturbed by weather, resulting in inaccurate data obtained by optical remote sensing in monitoring vegetation. Microwave remote sensing technology can not only monitor and measure all weather, all day, but also pass through vegetation. These advantages not only complement the shortcomings of optical remote sensing, but also directly promote the development of microwave remote sensing in agriculture. In this paper, the mechanism of electromagnetic scattering of wheat on random rough surface by polarimetric interferometric SAR (SAR) is studied, and the system software of electromagnetic scattering echo response of wheat is constructed. First of all, in the process of using Pol-InSAR to process the signal, the complex data information of the two sets of SAR images is obtained by surveying the area first, and the data information of the two sets of SAR images is registered, filtered, and interferentially processed according to the image registration, filtering and interference processing. The phase unwrapping and digital elevation inversion are studied, and the 3D coordinates of the surveyed area are obtained. If the radar data is visualized quickly, the corresponding digital elevation information can be obtained. Because the accuracy of digital elevation is determined by the quality of phase unwrapping, several phase unwrapping methods are compared in this paper in order to provide users with timely information so as to achieve the purpose of monitoring wheat growth. Then, the relation between the incidence angle of random rough surface and the backscattering coefficient is studied and the simulation is completed. The relation between the incidence angle and the backscatter coefficient of wheat can be clearly seen by the abstract description of wheat and the construction of physical model. Based on the establishment of wheat model, the polarization and correlation characteristics of wheat were studied, and the relationship between incidence angle and backscattering coefficient was established, which laid a foundation for quantitative retrieval of wheat biophysical parameters by microwave remote sensing. The main work of this paper is as follows: 1. The process and steps of Pol-InSAR signal processing are introduced. After reading the main and auxiliary SAR image data, image registration, interferogram generation, noise filtering, phase unwrapping and so on, 3D digital elevation model reconstruction. 2. In this paper, the modeling method of random rough surface is studied, and some of the methods are briefly described. Among them, the classical Kirchhoff approximation theory and the improved integral equation method (AIEM) are described in detail. In this paper, a statistical extended improved integral equation method (SEAIEM) algorithm. Wheat is abstracted into a physical model, and wheat leaves, stems and culms are abstracted into disk, needle and finite columns, respectively, and the relationship between the physical model and the backscattering coefficient is obtained by using the generalized Rayleggins calculation. Build the theoretical basis for the next wheat overall modeling. 4. After coherent superposition of random rough surface and wheat physical model, the whole wheat model can be reconstructed, and the parameters of wheat and rough surface can be selected. The relationship between the microwave backscattering coefficient and the incidence angle of wheat can be obtained accurately, which provides a theoretical basis for the retrieval of wheat biomass in the later stage. The above research contents are designed by MATLAB GUI interface, and the electromagnetic scattering echo response system software of wheat is constructed.
【学位授予单位】：宁夏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S512.1;TP722.6

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