摘要
该文讨论二向性反射分布函数(BRDF)在遥感领域中两方面的应用:(1)晴天大气层顶部的反照率的确定,(2)二向性反射分布函数对邻近象元点扩散函数和大气订正的影响。大气层顶部的光谱反照率是从多角度成象光谱辐射计(MISR)提取的重要参数,其精度主要取决于我们对不同情况表面建立更好的BRDF模型。该文论述一种与9个MISR二向性反射观测值相匹配的半经验函数的算法,并可进而通过数值积分产生4个光谱波段的晴天大气层顶部的光谱反照率。结果显示反照率的绝对精度对可见光波段可高于1%,对近红外波段可高于2%。采用一种简化的辐射通量模型,我们的工作显示邻近象元点扩散函数(PSF)的形状取决于下垫面表面的BRDF。在给定与中心象元的偏移(x,y)的条件下邻近象元的点扩散函数,由和沿观察方向的散射相函数的传输加权的乘积的积分给定。
In this paper we will discuss two uses of BRDFs in remote sensing: (1) in determining the clear sky top of the atmosphere (TOA) albedo, (2) in quantifying the effect of the BRDF on the adjacency pointspread function and on atmospheric corrections. The TOA spectral albedo is an important parameter retrieved by the Multiangle Imaging SpectroRadiometer (MISR). Its accuracy depends mainly on how well we can model the surface BRDF for many different situations. We will present results from an algorithm which matches several semiempirical functions to the nine MISR measured BRFs that are then numerically integrated to yield the clear sky TOA spectral albedo in four spectral channels. We show that absolute accuracies in the albedo of better than 1 % are possible for the visible and better than 2 % in the near infrared channels. Using a simplified extensive radiosity model, we will show that the shape of the adjacency pointspread function (PSF) depends on the underlying surface BRDFs. The adjacency pointspread function at a given offset (x,y) from the center pixel is given by the integral of transmissionweighted products of BRDF and scattering phase function along the line of sight.
出处
《遥感学报》
EI
CSCD
1997年第S1期200-205,共6页
NATIONAL REMOTE SENSING BULLETIN
关键词
晴空反照率
BRDF
邻近效应
大气点扩散函数
Clear sky albedo, BRDF, Adjacency effect, Atmospheric point spread function