成像光谱矿物识别方法与识别模型评述

矿物识别和矿物填图是成像光谱应用最成功的领域之一。本文将国内外发展的矿物识别模型归纳为光谱匹配和以知识为基础的智能识别两大类型进行讨论。对光谱匹配方法分别从其方法的分类、光谱相似性测度、整体光谱匹配算法、局部光谱识别、亚像元光谱识别、混合像元分解和矿物端元选择、光谱减维和噪声弱化等方面作了评述。最后，讨论了矿物识别和填图研究中存在的主要问题，指出研究建立全谱段矿物识别方法和技术体系将是今后光谱矿物识别和矿物填图的重要发展方向。     

高光谱矿物填图技术与应用研究

回顾和总结了"九五"以来,中国国土资源航空物探遥感中心在高光谱矿物识别和矿物填图领域所取得的成果,包括主要岩矿光谱特征与影响因素分析;矿物的种类识别、丰度反演和成分识别;中—热红外多/高光谱的数据处理和矿物识别;高光谱矿物识别的地质应用模式、矿物填图的工作方法和技术流程、矿物填图的技术体系;矿物填图在区域地质找矿、矿区勘查和成矿与找矿模型、植物地球化学探测、矿山环境监测以及月球和行星探测等方面的应用示范。最后,提出了高光谱矿物填图近期的研究方向。     

光谱角度填图方法及其在岩性识别中的应用

光谱角度填图（ＳＡＭ）是成像光谱图像处理技术中,对岩石矿物进行谱形识别的主要方法之一,但其应用效果并不十分理想。以内蒙古渣尔泰山为实验区,从岩石实验室反射光谱的相似系数聚类分析入手,研究了光谱角度填图方法的优劣,及其产生的原因。探讨了利用均值图像参与分类的处理方案,从而改善了光谱角度填图方法中易于产生“异类同谱”的不足,获得良好的岩性识别效果。     

新疆哈密三种典型蚀变矿物的HyMap高光谱遥感信息提取

利用机载的可见光、近红外及短波红外成像光谱(ＨyMap)数据,对新疆哈密地区岩矿信息识别方法进行研究。基于方解石、 绿泥石和绢云母3种常见蚀变矿物的光谱特征,在遥感数据定标和反射率图像转换的基础上,应用光谱角度模型（SAM）分类法进行自 动匹配识别和信息提取。通过掩膜技术进行方解石、绿泥石和绢云母矿物填图,并结合实验室光谱数据库光谱进行了验证。     

成象光谱图象光谱吸收鉴别模型与矿物填图研究

本文提出了一种光谱吸收鉴别模型，拟通过矿物光谱吸收特征的鉴别，在成象光谱上实现矿物直接识别与填图。该模型的核心是光谱吸收指数技术（ＳＡＩ）。从理论上探讨了ＳＡＩ的本质，应用Ｈａｐｋｅ光谱模型讨论了ＳＡＩ与光谱吸收系数（ｄ）以及单散射反照率（ｗ）之间的函数关系，并从成象光谱图象辐射信息传递过程分析了图象ＳＡＩ与光谱吸收深度的关系，而光谱吸收深度与岩石矿物成分含量之间具有定量关系，这显示了ＳＡＩ提取矿物定量遥感信息能力。ＳＡＩ已经成功地应用于ＦＩＭＳ、ＭＡＩＳ和ＧＥＲＩＳ图象处理与矿物填图，本文通过哈图、塔里木、以及澳大利亚松谷的实例研究，表明ＳＡＩ是一种有效的提取矿物类型与丰度信息的方法。     

高分五号高光谱影像矿物精细识别

矿物识别是高光谱遥感技术优势之一,已在地质矿产领域取得了显著应用效果。随着光谱分辨率的不断提高,高光谱遥感矿物识别逐渐从识别矿物种类向矿物亚类、矿物成分等精细信息识别发展,且随着应用实践的不断深入,对矿物精细信息的需求也越来越大。而光谱分辨率和矿物识别方法是制约高光谱矿物精细识别的主要因素。高分五号(GF-5)超高的光谱分辨率为矿物精细识别提供了可能。首先在分析总结已有高光谱矿物识别方法优缺性的基础上,提出了综合光谱特征增强匹配度和特征参量的矿物识别方法;其次,选取甘肃柳园和美国Cuprite两个研究较多的地区为研究对象,基于GF-5卫星数据开展了矿物精细识别,在完成矿物种类、亚类识别的基础上,进一步对绢云母成分信息进行了反演;最后,结合上述地区已有机载高光谱数据及填图结果开展对比分析。结果表明:GF-5矿物识别信息分布与机载HyMap、AVIRIS一致性很好,相较机载数据GF-5矿物识别平均正确率优于90%,说明本研究提出的矿物识别方法能够满足GF-5矿物精细识别,可为后续业务化应用提供技术支撑,同时认为超高的光谱分辨率使得GF-5在矿物成分信息识别上更具优势。     

基于二次散射非线性混合模型的矿物填图方法

传统的遥感地质填图方法较少考虑到一个像元中多种地物共生存在的情况,因此所填图件难以反映矿物的分布特征。针对线性混合模型解混精度不高的问题,使用二次散射非线性混合模型对高光谱数据进行光谱解混,并在此基础上,提出了k(k≥2)类地物的填图规则。采用美国内华达州Cuprite地区AVIRIS数据进行填图实验,将其结果与Clark等的填图结果进行对比。实验结果表明:与线性模型的矿物填图相比,基于二次散射非线性混合模型所填图件更加接近矿物的真实分布;使用k(k≥2)类矿物填图规则的填图结果细节丰富,与Clark等人的填图结果吻合度高。     

成像光谱遥感数据的光谱重建研究

成像光谱遥感数据处理中的一个重要环节是大气辐射纠正，它是成像光谱遥感定量化的重要部分，本文推导出一种简单的方法，对高光谱分辨率航空遥感图象进行大气纠正，反射率图像转换及光谱重建，并在地质资源遥感调查中应用，取得很好的效果，同时，对重建的地物光谱中出现的误差，进行了分析。     

泰国高光谱矿物填图与矿产数据库建立

高光谱遥感,在成像过程中,它利用成像光谱仪,在可见光、近红外、中红外、热红外波段范围内,获取许多非常窄的连续光谱的影像数据,其成像光谱仪可以收集到上百个非常窄的光谱波段信息,实现了地物的空间信息、辐射信息、光谱信息的同步获取。本文基于遥感平台,对泰国研究区的Hyperion数据进行研究,采用光谱角矿物填图(SAM)方法进行填图,对研究区矿产预测评价起到了良好的辅助效果。在现代地理信息系统学科技术和地理数据库的基础上,将泰国研究区中所获得的地质、遥感、矿产等相关数据资料进行入库,建立泰国国家的数据库。     

基于神经网络的二类水体大气校正

以MERIS高光谱影像为数据源,根据现有大气传输模型和大气校正方法,探索了适合于内陆湖泊二类水体的高光谱遥感影像大气校正方法。在6S辐射传输模型的基础上,构建了基于神经网络的二类水体大气校正算法。通过构建输入卫星辐亮度直接提取离水反射率的模型,无需同步气溶胶参数,即可实现大气校正。对2010年8月9日的MERIS影像进行大气校正,并将校正后的遥感反射率与准同步实测离水反射率进行对比分析,结果表明,大气校正过程有效去除了大气效应的影响,经过大气校正的13个波段的平均相对误差分布在10%～40%,得到了与实测值相近的水体遥感反射率。     

热红外遥感火星矿物填图方法初步研究及应用

利用热辐射光谱仪（TES）数据,对火星进行热红外遥感矿物填图。通过对几种典型填图方法的简要介绍,结合火星环境及方法的使用条件,对填图结果进行简单比较,初步分析了填图方法的差异性,为火星矿物填图的进一步研究提供了基础,并为方法和模型的进一步改进提供了依据。     

Improved k-means and spectral matching for hyperspectral mineral mapping

Mineral mapping is an important step for the development and utilization of mineral resources. The emergence of remote sensing technology, especially hyperspectral imagery, has paved a new approach to geological mapping. The k-means clustering algorithm is a classical approach to classifying hyperspectral imagery, but the influence of mixed pixels and noise mean that it usually has poor mineral mapping accuracy. In this study, the mapping accuracy of the k-means algorithm was improved in three ways: similarity measurement methods that are insensitive to dimensions are used instead of the Euclidean distance for clustering; the spectral absorption features of minerals are enhanced; and the mineral mapping results are combined as the number of cluster centers (K) is incremented from 1. The improved algorithm is used with combined spectral matching to match the clustering results with a spectral library. A case study on Cuprite, Nevada, demonstrated that the improved k-means algorithm can identify most minerals with the kappa value of over 0.8, which is 46% and 15% higher than the traditional k-means and spectral matching technology. New mineral types are more likely to be found with increasing K. When K is much greater than the number of mineral types, the accuracy is improved, and the mineral mapping results are independent of the similarity measurement method. The improved k-means algorithm can also effectively remove speckle noise from the mineral mapping results and be used to identify other objects.     

高光谱遥感技术在地质领域中的应用

近年来，高光谱应用技术在地质领域得到了深入的应用与发展，不仅深化了地质学的基础研究，也推动着遥感地质填图从岩 性填图向矿物填图的飞跃，推进了高光谱遥感技术在成矿预测、地质成生环境成因信息探测、植被地化信息与理化信息提取以及矿 山环境调查等应用的不断深入。本文围绕高光谱技术的特点，并结合作者近年来的工作实践，论述了高光谱技术在上述领域的实际 应用情况与应用效果。     

Aqueous alteration mapping in Rishabdev ultramafic complex using imaging spectroscopy

Hyperspectral remote sensing/imaging spectroscopy has enabled precise identification and mapping of hydrothermal alteration mineral assemblages based on diagnostic absorption features of minerals. In the present study, we use Airborne Visible InfraRed Imaging Spectrometer-Next Generation (AVIRIS-NG) datasets acquired over Rishabdev ultramafic suite to derive surficial mineral map using least square based spectral shape matching in wavelength range of diagnostic absorption features of minerals. Resulting mineral map revealed presence of hydrothermally altered serpentine group of minerals and associated alteration products (talc and dolomite) along with clays and phyllosilicates. Mineral maps are validated using field spectral measurements and published geological map. Involvement of low temperature (<350 °C) hydrothermal fluid in serpentinization of ultramafic rocks in the region is inferred from analysis of deepest absorption features of muscovites at 2.20 μm, spectral abundance of lizardite and absence of prenhite-pumpyllite facies mineral assemblages. Talc was found to be the most common alteration product of serpentines followed by dolomites. Intense alteration of serpentines to talc along the fracture zone is attributed to the circulation of carbon dioxide rich hydrothermal fluids along these conduits. Kaolinite and halloysite are primarily associated with granites and are the result of hydrothermal alteration of plagioclase feldspar in granites while muscovite and illites are generally associated with phyllites and quartzites . The study demonstrates the potential of imaging spectroscopy for mapping hydrothermal alteration mineral assemblages in ultramafic complex.     

Evaluation of ICA and CEM algorithms with Landsat-8/ASTER data for geological mapping in inaccessible regions

Many regions remain poorly studied in terms of geological mapping and mineral exploration in inaccessible regions especially in the Arctic and Antarctica due to harsh conditions and logistic difficulties. Application of specialized image processing techniques is capable of revealing the hidden linear mixing spectra in multispectral and hyperspectral satellite images. In this study, the applications of Independent component analysis (ICA) and Constrained Energy Minimization (CEM) algorithms were evaluated for Landsat-8 and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) remote sensing data for geological mapping in Morozumi Range and Helliwell Hills areas, Northern Victoria Land (NVL), Antarctica. The results of this investigation demonstrate the capability of the two algorithms in distinguishing pixel and subpixel targets in the multispectral satellite data. The application of the methods for identifying poorly exposed geologic materials and subpixel exposures of alteration minerals has invaluable implications for geological mapping and mineral exploration in inaccessible regions.     

Mapping alteration minerals using sub-pixel unmixing of ASTER data in the Sarduiyeh area,SE Kerman,Iran

This paper is an attempt to introduce the role of earth observation technology and a type of digital earth processing in mineral resources exploration and assessment. The sub-pixel distribution and quantity of alteration minerals were mapped using linear spectral unmixing (LSU) and mixture tuned matched filtering (MTMF) algorithms in the Sarduiyeh area, SE Kerman, Iran, using the visible-near infrared (VNIR) and short wave infrared (SWIR) bands of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument and the results were compared to evaluate the efficiency of methods. Three groups of alteration minerals were identified: (1) pyrophylite-alunite (2) sericite-kaolinite, and (3) chlorite-calcite-epidote. Results showed that high abundances within pixels were successfully corresponded to the alteration zones. In addition, a number of unreported altered areas were identified. Field observations and X-ray diffraction (XRD) analysis of field samples confirmed the dominant mineral phases identified remotely. Results of LSU and MTMF were generally similar with overall accuracy of 82.9 and 90.24%, respectively. It is concluded that LSU and MTMF are suitable for sub-pixel mapping of alteration minerals and when the purpose is identification of particular targets, rather than all the elements in the scene, the MTMF algorithm could be proposed.