REFLECTANCE SPECTROSCOPY - QUANTITATIVE-ANALYSIS TECHNIQUES FOR REMOTE-SENSING APPLICATIONS
REFLECTANCE SPECTROSCOPY - QUANTITATIVE-ANALYSIS TECHNIQUES FOR REMOTE-SENSING APPLICATIONS
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DOI：
10.1029/jb089ib07p06329
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发表时间：
1984-01-01
影响因子：
--
通讯作者：
ROUSH, TL
中科院分区：
文献类型：
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作者：
CLARK, RN;ROUSH, TL
比较了遥感反射率数据分析的几种方法，包括经验方法和散射理论，这两种方法对解决遥感问题都很重要。提出了光子平均光程长度的概念及其在反射光谱建模中的应用。结果表明，颗粒表面的平均光程长度与吸收系数的平方根大致成反比。因此，材料的吸收剂越强，穿透到表面的光子就越少。提出了表观吸收率（-反射率）的概念，并表明当绘制为吸收系数（真实吸收率）与光子能量时形状为高斯的吸收带在表观吸收率中也是高斯的。然而，表观吸光度中的高斯曲线具有较小的强度和大0.02倍的宽度。反射光谱中的表观连续谱被建模为用于隔离特定吸收特征以进行分析的数学函数。它示出，连续应通过将其划分为反射光谱或从表观吸光度减去它来去除，并且高斯函数到吸收特征的拟合应使用表观吸光度与光子能量来完成。Kubelka-Munk理论仅适用于具有小的总吸收和双半球反射率的材料，这在地质遥感中很少遇到。结果表明，最近提出的双向反射理论有可能用于推导矿物丰度的反射光谱。
Several methods for the analysis of remotely sensed reflectance data are compared, including empirical methods and scattering theories, both of which are important for solving remote sensing problems. The concept of the photon mean optical path length and the implications for use in modeling reflectance spectra are presented. It is shown that the mean optical path length in a particulate surface is in rough inverse proportion to the square root of the absorption coefficient. Thus, the stronger absorber a material is, the less photons will penetrate into the surface. The concept of apparent absorbance (‐In reflectance) is presented, and it is shown that absorption bands, which are Gaussian in shape when plotted as absorption coefficient (true absorbance) versus photon energy, are also Gaussians in apparent absorbance. However, the Gaussians in apparent absorbance have a smaller intensity and a width which is a factor of √2 larger. An apparent continuum in a reflectance spectrum is modeled as a mathematical function used to isolate a particular absorption feature for analysis. It is shown that a continuum should be removed by dividing it into the reflectance spectrum or subtracting it from the apparent absorbance and that the fitting of Gaussians to absorption features should be done using apparent absorbance versus photon energy. Kubelka‐Munk theory is only valid for materials with small total absorption and for bihemispherical reflectance, which are rarely encountered in geologic remote sensing. It is shown that the recently advocated bidirectional reflectance theories have the potential for use in deriving mineral abundance from a reflectance spectrum.