On the derivation of kernels for kernel‐driven models of bidirectional reflectance
On the derivation of kernels for kernel‐driven models of bidirectional reflectance
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DOI：
10.1029/95jd02371
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发表时间：
1995-10
影响因子：
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通讯作者：
W. Wanner;Xiaowen Li;A. Strahler
中科院分区：
文献类型：
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作者：
W. Wanner;Xiaowen Li;A. Strahler
本文导出了Ross（1981）的小叶面积指数辐射传输理论的一个新近似和Li和Strahler（1992）的几何光学互影模型的两个新近似。这些，连同Roujean et al.（1992）对Ross大LAI理论的近似及其矩形凸起的几何光学模型，可用于通过线性组合建立陆面双向反射分布函数（BRDF）的半经验模型。由于叠加的函数仅取决于观察和照明几何，因此导出的BRDF模型可以称为核驱动的;但是Nilson和Kuusk（1989）的Walthall等人的修改版本。（1985）模型是属于这一类的经验模型的一个例子。内核驱动模型的线性度在几个方面有利于全局BRDF和BRDF处理需求，最显著的是分析可逆性，使得查找表方法可以用于BRDF计算，适应混合像素情况和空间缩放。这里讨论的模型被提出用于NASA地球观测系统（EOS）的中分辨率成像光谱仪（MODIS）传感器的BRDF/BRDO处理。
A new approximation to Ross' (1981) radiative transfer theory for small values of leaf area index (LAI) and two new approximations to Li and Strahler's (1992) geometric-optical mutual shadowing model are derived. These, together with Roujean et al.'s (1992) approximation to Ross' theory for large LAI and their geometric-optical model of rectangular protrusions, may be used for formulating semiempirical models of the bidirectional reflectance distribution function (BRDF) of the land surface through linear combinations. Because the functions superimposed depend only on viewing and illumination geometry, the BRDF models derived may be called kernel-driven; but Nilson and Kuusk's (1989) modified version of Walthall et al.'s (1985) model is an example of an empirical model that belongs to this same class. The linearity of kernel-driven models is advantageous to global BRDF and albedo processing needs in several respects, most notably analytical invertibility, making possible look-up table approaches to albedo calculation, accommodation of mixed pixel situations, and spatial scaling. The models discussed here are being proposed for BRDF/albedo processing for the moderate resolution imaging spectroradiometer (MODIS) sensor of NASA's Earth Observing System (EOS).