基于包络线消除法的岩石光谱对应分析

Correspondence Analysis of Rock Spectra Based on Continuum Removing

岩石光谱特征是岩性识别的物理基础。选取常见的10种岩石类型15种岩石样品的光谱数据,对其进行均值、重采样、平滑、水汽吸收波段拟值等预处理,以消除岩石光谱噪声,然后通过包络线消除法,获得了岩石光谱特征参数,发现云母板岩(风化面)吸收特征最为明显;对包络线消除处理后的光谱数据进行对应分析,提取出R型主因子载荷,得到第一主因子轴代表主要的阳离子、阴离子诊断波段和水分子吸收波段,第二主因子轴代表少数阳离子的特征波段,获得与岩石相关的特征波段为385～525nm、735～1 365nm、1 435～1 785nm、1 890～1 952nm、1 995～2 310nm,并找出了主要吸收波段的物理含义。通过对应分析二维图像,将岩石光谱分为4类,从第一类到第四类吸收深度逐渐变浅,吸收面积呈递减趋势,吸收宽度逐渐变窄,吸收峰逐渐增多,Fe2+和Fe3+吸收峰增多,铁化、泥化蚀变现象更明显。用聚类分析法对分类结果进行验证发现,分类结果有较好的对应性。从而为岩石和成像光谱图像数据精细分类提供参考依据,实现了对岩石高光谱海量数据的有效提取,进而为遥感矿产预测和找矿提供依据。

Spectral feature is the physical basis of rock identification.In order to remove the rock spectral noise,the spectra including common 15 rock samples belonging to 10 rock types are pretreated by averaging,resampling,smoothing,and fitting the value of water vapor absorption band.The continuum removing methods are used to obtain absorption-band parameters of spectra.Among the rock samples,the mica slate＇s absorption feature is the most obvious.The normalized data studied by using R-mode principle factor method shows that the first principal factor axis represents the major absorption spectra of cations,anions and water vapor,and the second represents a small number of cation band.The characteristic spectral bands of the rock are 385-525 nm,735-1 365 nm,1 435-1 785 nm,1 890-1 952 nm and 1 995-2 310 nm.The physical meanings of these bands are also identified.The rock spectra are classified into four types by two-dimensional image analysis.From first type to last type,the spectra prove the gradually shallow absorption depth,the decreasing area,the gradually narrowing width and the increasing number of absorption peaks.Iron and pelitization alteration phenomenon are obvious.The classification results verified by cluster analysis are of better correspondence.A physical basis for rock classification and identification are provided by remote sensing technology.It is of significance to abstract effectively hyper spectral data and classify hyper spectra images.