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土地质量高光谱遥感监测方法研究

The Study of Applying Hyper-spectral Remote Sensing Technology in Land Quality Monitoring

【作者】 何挺

【导师】 林宗坚;

【作者基本信息】 武汉大学 , 摄影测量与遥感, 2003, 博士

【摘要】 土地资源作为资源与生态环境系统中的重要要素和诸多生态环境问题的集中体现者,土地资源利用是可持续发展最重要的组成部分。要进行土地资源的高效管理,必须进行土地质量的监测。随着土地资源管理从数量管理向质量管护和生态管护方向发展,对土地动态监测也提出了更高的要求,土地动态监测将从以往单一的土地数量监测向土地质量监测发展。通过采集、分析和解译一系列时相的定量化数据,获取土地质量的及时可靠的信息,探测土地质量的变化,而这些变化可能正是土地开始进化或退化的信号。及早识别土地质量变化上的任何不利趋势,对于土地资源管理决策,最终实现可持续土地利用具有重要意义。高光谱分辨率遥感将反映地物性质的光谱与确定其空间和几何关系的图像革命性地结合到了一起,在获取研究对象的影像的同时获得每个像元的光谱分布,定量分析地球表面生物物理化学过程和参数,为土地质量监测提供了一种新的技术手段,使得土地质量监测各指标的定量反演成为可能。 本研究将高光谱分辨率遥感技术引入到土地质量监测中,探索将其应用于土地质量监测中的潜力。根据高光谱遥感的技术特点结合土地质量指标光谱特点,运用多元统计分析技术、基于光谱位置变量的分析技术等方法,通过对试验区不同土样的地面光谱特征分析和理化特性分析,选择高光谱遥感技术手段所能监测的若干直接或间接反映土地质量状况的光谱指标,初步建立土地质量指标的光谱指标模型,进行高光谱遥感土地质量监测的潜力研究,希望借助高光谱遥感这一新兴技术,达到提高土地质量监测的水平,扩展监测内容,降低调查成本,缩短调查周期,提高调查成果的科学性、客观性和稳定性的目的。 从针对土地“维持生物活动、多样性和生产力”这一功能的土地质量出发,论文重点研究了利用高光谱遥感技术监测土壤有机质含量、水分含量、氧化铁含量等土地质量指标的方法。论文主要研究内容包括:第二章进行了野外波谱测量及其影响因素研究。论述了地物光谱测试时太阳高度角、太阳方位角、云、风、相对湿度、入射角与探测角、仪器扫描速度、仪器视场角、仪器的采样间隔和光谱分辨率、坡向、坡度、目标本身光谱特性等等各种因素对测量结果影响;第三、四、五章利用光谱特征提取、多元统计回归、光谱微分等技术分别对土壤有机质含量、水分含量、氧化铁含量这三个指标与土壤光谱反射特性之间进行了研究,分析了反射率的各种变换形式对这三个土壤理化指标的敏感程度,建立了反演模型;第六章进行了OMIS影像几何校正、辐射纠正和参数成图研究。与卫星遥感传感器相比,机载成像光谱仪具有平台姿态稳定性差、飞行高度低、视场角较大等特点,这些因素的结合使得图像几何畸变的图案十分复杂化,在详细分析OMIS图像存在的主要几何畸变的基础上提出了OMIS图像几何校正的处理流程。利用OMIS影像的辐射校正后生成的反射率图像,进行土壤有机质含量、水分含量、氧化铁含量指标的参数成图,并将建立的地面模型应用到影像中。 论文的主要研究结论和创新点总结如下: 卜王壤有机质含量与土壤光谱反射特性的关系及其有机质含量反演 有矶质左研究的350一250Onm波长范围内并不存在吸收峰,但在这一波长范围内,光谱反射率与有机质含量呈负相关关系,在675nm附近的相关性最强。总体而言,在进行微分变换以前,可见光波段的有机质含量探测能力要比近红外波段要强,最敏感的区域在675nln附近:光谱微分变换以后,近红外波段要更敏感一些,反射率对数的一阶微分在2187nm处与有机质的相关性可达0.89,在本研究同类相关系数中的最大值。在研究的反射率的各种变换形式中,反射率的对数的一阶数分对土壤有机质含量最为敏感,这是由于反射率的对数变换减少了因光照条件变化的乘性因素豹影响,而光谱微分能去除部分线性或接近线性的背景、噪声光谱对目标光谱的影响。最后建立由849nm、168Inln、2187nm三个波段的反射率对数的一阶微分为自变量的回归方程,预测能力较强。 2、土壤表面含水量与土壤光谱反射特性关系及其含水量反演模型 在预测土壤含水量时,145Onln吸收峰比1925吸收峰要更为敏感有效,而.且前者的吸收峰位置与含水量高度相关,随着土壤含水量的增加吸收峰位置有向中红外方向偏移的现象,而19扑黝近的吸收峰则没有这种现象。研究结果发现土壤含水量与145Onm处的光谱吸收特征峰面积、位置和深度均存在良好的线性回归关系,说明利用地物光谱仪直接测量土壤光谱,从而对土壤表层含水量进行测定是可能的,可考虑将地物光谱仪进行改造,建立一种新型的专门用于测定土壤表层含水量测定仪器,有望达到野外实时、实地、全天候、大面积快速测量的目的。研究结果还表明,反射率的对数的一阶微分这一变换能大幅度增强光谱数据与土壤含水量之间的相关性,变换后担关系数的最大值从变换前的一0.52482提高到为一0.90068。 3土壤氧化铁含量与土壤土壤光谱反射特性关系及其反演模型 士_壤中氧化铁的含量与反射率呈负相关,氧化铁含量的增加,会导致土壤反射率一F降,这跟有澎I质是一样的,但是氧化铁对反射率的

【Abstract】 Land resource is a key factor of environments system and a centralized reflection of many environments issues. Land resource utilization is the most important part of sustainable development. To manage land resource efficiently, we need to monitor land quality. With the development of land resource management transferred from quantity management to quality and ecology protection, it required more advanced approaches to dynamic land monitoring. Dynamic land monitoring will develop to land quality monitoring from land quantity monitoring. Access timely and reliable information of land quality by collecting, analyzing and interpreting of a serial temporary quantitive data, we can explore the change of land quality. These changes are exactly signals of land improvement or degradation. It is significant to land management decision, especially to achieve the goal of sustainable land use that we identify adverse trends on land quality changes in advance. High spectral resolution remote sensing integrated the spectrum which reflects material features and the image which decides geometric relationship innovatively. Obtaining the spectra distribution of each pixel while acquiring the image of ground object and quantitatively analyzing the process of bio-physical and chemistry and parameters, it provides a new technology means for land quality monitoring and makes it possible to quantitative retrieval many land quality monitoring indicators.This paper applied hyperspectral remote sensing technique to land quality monitoring to explore its application potential in this field. According to the characteristics of hyperspectral remote sensing technique and spectral features of land quality indicators, we use multivariate statistics methods and approaches based on spectral position variables, select several spectral indicators which directly or indirectly reflect land quality, set up the retrieval models of land quality indicator, study the potential of applying hyperspectral remote sensing technique in land quality monitoring. Attempt to ameliorate land quality monitoring techniques, expand monitoring extents, decrease the self cost of survey, shorten the survey period, and make the results more scientific, objective and stable by this technique.From the view of the production function of land, this paper mainly study the methods of monitoring the land quality indicators (such as SOM, moisture, Fe2O3) by hyperspectral remote sensing technique. The main content of this paper includes: chapter 2 mainly discusses field spectral collection and its influence factors. The collection of accurate spectra in the field requires an awareness of the influences of the various sources of illumination, atmospheric characteristics and stability, winds, instrument field of view, target viewing and illumination geometry, instrument scanning time, and the spatial and temporal variability of the characteristics. Chapter 1 discussed how these factors influence spectrum measure result; The third, forth and fifth chapters studied the relationship between soil spectralIVreflection feature and three land qulity indicators (SOM, moisture and Fe2O3), analyzed the sensitive degree of various albedo transformation to this three soil phys-chemica! indicators, and set up retrieval model; The sixth chapter studied geometric rectification and atmospheric radiation correction of OMIS data and realized land quality parameter mapping.The main conclusions and innovation are:1. the relationship between SOM and soil spectral reflection features and retrieval model of SOM.SOM has no absorption peak in the region from 350nm to 2500mm in consideration, but in this wavelength region, spectral reflectance is negative correlation with SOM, and has high correlation in region around 675nm. As a whole, the detection ability of SOM in visible band is more powerful than in near infrared band. The most sensitive band is around 675nm. The ability in near infrared band is more sensitive after spectral derivative transformaton. The correlation coefficient between order

  • 【网络出版投稿人】 武汉大学
  • 【网络出版年期】2004年 04期
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