中国科学院遥感与数字地球研究所-高光谱遥感应用技术研究室

【作者】             张文娟                                                                                                                                            

【导师】             童庆禧；张兵；郑兰芬

【 学位年度 】    2008

【论文级别】      博士    

【关键词】          高光谱遥感，三角共路型，干涉成像光谱仪，图像模拟，光谱复原  

【Key words】   Hyperspectral Remote Sensing; Sagnac Imaging Fourier Transform Spcetrometer; Image Simulation; Spectra Recovery 

【中文摘要】

图像模拟是航空航天遥感器指标论证与优化的重要环节，也可为应用模型预先开发提供数据源支持。目前三角共路型（Sagnac）傅里叶变换成像光谱仪发展很快，但对应的图像模拟模型研究还处于起步阶段。尤其在我国，干涉成像光谱仪已成为我国航天高光谱遥感探测的重要手段，搭载中科院西安光机所干涉成像光谱仪的“嫦娥一号”卫星也于2007 年10 月24 日成功发射升空，即将发射的环境与灾害监测预报小卫星星座中的HJ-1A 星上也装载了HJY20-1-A 干涉成像光谱仪。在色散型航空成像光谱仪的数据处理研究方面我国已经积累了比较丰富的经验，但在干涉成像光谱仪数据预处理和应用研究方面还十分薄弱。因此，开展以光谱复原为核心的干涉成像光谱图像模拟工作就显得十分重要。

        本文拟在研究并建立三角共路型干涉成像光谱仪的图像模拟方法和技术体系基础上，使其成为评价和展示三角共路型干涉成像光谱仪系统性能的有效工具，并为改进和提高现有干涉光谱成像系统性能提供技术方法。在光谱图像模拟的基础上，论文对我国HJY20-1-A 高光谱成像仪进行了主要载荷参数的论证，分析了干涉成像光谱仪光谱复原的影响因素，给出了改进方案，形成了三角共路型干涉光谱成像系统的图像模拟、参数评价以及算法改进体系。

        本文的研究工作主要分为四个部分：

1. 干涉成像光谱仪光谱成像原理分析与比较。在研究多种成像光谱仪的光谱成像原理基础上，对干涉成像光谱仪与色散型成像光谱仪，迈克尔逊型（Michelson）干涉成像光谱仪与三角共路型干涉成像光谱仪进行全面的比较分析。

2. 三角共路型干涉成像光谱仪入瞳辐亮度模拟。论文首先建立了三角共路型干涉成像光谱仪图像模拟的总体方案，将图像模拟分为地物景象光学特性模拟、大气辐射传输过程模拟与遥感器成像过程模拟三大部分。针对地物景象光学特性模拟，论文提出了基于精细分类、光谱匹配以及光谱变异性分析的光谱生成，基于光谱解混、光谱匹配与光谱混合的光谱生成，以及基于光谱内插的光谱生成三种方法。以AVIRIS 航空高光谱数据为地物景象数据源、在典型地物波谱数据库的支持下，模拟生成了的高空间、超光谱分辨率的反射率光谱图像。在此基础上，采用6S 大气辐射传输模型，生成高空间、超光谱分辨率的入瞳辐亮度图像。

3. 三角共路型干涉成像光谱仪成像过程模拟。干涉成像光谱仪遥感器过程模拟分为空间响应模拟、干涉图像生成模拟以及探测器响应模拟三个模块。论文对模拟的主要误差来源进行了系统分析，并建立了噪声模拟方法。对我国的CE-1和HJY20-1-A 干涉成像光谱仪进行了原始干涉维图像数据模拟，分析了一些重要载荷指标对复原光谱的影响。

4. 三角共路型干涉成像光谱仪复原光谱影响因素分析。分析了切趾函数和复原光谱波长变化对光谱图像应用的影响。研究表明切趾函数的应用可以提高复原光谱精度，但当最大光程差较小时，切趾函数作用下的复原光谱精度仍然不高，为此，本文提出了基于仪器线型函数标准化的光谱复原改进算法。根据不同波长分辨率的复原光谱关系，本文就几种典型植被参数，给出了HJY20-1-A 高光谱成像仪与Hyperion 的等效算法。

【Abstract】

To evaluate sensor design artifacts and properties, it is useful to simulate their designs using a radiometric correction ray-tracing tool. Imaging simulation of data of optoelectronic remote sensing systems plays an important role in the development, optimization, calibration, test, and application of such instruments and the interpretation of their data products. Imaging Fourier Transform Spectrometers (IFTS) are becoming popular sensors for hyperspectral remote sensing, but the image simulation of these sensors is still in its preliminary stage. In China, Imaging Fourier Transform Spectrometers are becoming the primary spaceborne imaging spectrometers. One sagnac Fourier transform spectrometer onboard Chang'e-1 is developed by Xi'an Institute of Optics and Precision Mechanics of CAS. As the first China lunar probe satellite, Chang'e-1 was successfully launched in 2007 In addition, China small satellite “HJ-1A” ,which will be launched soon in this year, is also equipped with one imaging Fourier transform spectrometer (HJY20-1-A). In China, In comparison with the rich experience in data processing of airborne dispersive imaging spectrometer，the research on data process of IFTS is very limited. So it is very urgent and important to carry out imaging simulation of IFTS for data processing.

      The image simulator of sagnac IFTS is proposed in this thesis, to evaluate, demonstrate and improve the status of sagnac IFTS. The evaluation of the main technical parameters about HJY20-1-A was performed based on the simulator, and the parameters that affect the precision of recovered spectra are proposed and the improved algorithm is developed. Moreover, an integrity system is formed, which includes three functions: image simulation, parameter evaluation and algorithm improved.

    This thesis consists of four parts:

1. Analysis of imaging principle of IFTS and comparison with other types. IFTS and dispersive imaging spectrometer is compared, and Michelson IFTS is compared to SagnacITFS for their imaging principle.

2. Simulation of the incident radiance of Sagnac IFTS. First, the frame for Sagnac IFTS imaging simulation was constructed. The simulation frame was composed by three parts: scene reflectance image simulation, radiative transfer simulation and sensor system simulation. Three methods were utilized to simulate scene reflectance image. They were reflectance simulation based on classification, spectral matching and analysis of spectral variability; reflectance simulation based on spectral unmixing, spectral matching and spectral mixing; interpolation-based reflectance simulation. The ultra-spectral, high spatial reflectance image was simulated by these methods and using AVIRIS airborne reflectance data and spectral library. Then, the simulated reflectance image in conjunction with 6S radiative transfer model was used to simulate the incident radiance image.

3. Simulation of the sensor imaging process of Sagnac IFTS. The total imaging process consists of three modules: spatial response, interferogram simulation and detector. The artifacts and noises of the imaging process were analyzed comprehensively. The simulation model was given to consider the noise of base image. Then, interferograms of CE-1 and HJY20-1-A were simulated and payload parameters of HJY20-1-A were analyzed.

4. Analysis of the effects of recovered Sagnac IFTS spectra. Research indicts that the accuracy of reconstructed spectrum can be improved by apodization functions, but the accuracy was not very high, even limited for HJY20-1-A. Finally, an improved algorithm based on the standardization of the instrument line shape function (ILS) was proposed, the reconstructed spectrum by this algorithm was gained with higher accuracy. The relation of the reconstructed spectra at different spectral resolution was analyzed, and the formula between the typical vegetation indices of HJY20-1-A and Hyperion was built.