评估MODIS的BRDF角度指数产品

Assessment of MODIS BRDF shape indicators

应用地表观测的二向性反射数据集和多种MODIS数据产品,通过统计分析,对MODIS的二向性反射角度指数产品进行综合评估,结果表明:(1)MODIS角度指数包含了地表三维结构信息,有望用来反演地表的物理结构参数;(2)MODIS角度指数是内在的三维关系,各向异性因子(Anisotropic Factor:ANIF)和各向异性指数(Anisotropic Index:ANIX)高相关,建议去掉ANIF以精炼MODIS角度指数产品;(3)各向异性平整指数(Anisotropic Flat Index:AFX)较好地指示了地表基本散射类型的变化,且具有较小的类内方差,对改善特定地表分类精度可能会更有用。

Bidirectional Reflectance Distribution Function（BRDF） shape indicators of Moderate Resolution Imaging Spectroradiometer（MODIS） are among MODIS BRDF/Albedo products and are helpful in expanding the application of BRDF remote sensing data.This paper evaluates the MODIS BRDF shape indicators with the statistical analysis methods by using various collected ground BRDF datasets and MODIS products.Our result presents several major findings：（1） the MODIS BRDF shape indicators contain the information regarding 3-D structure of land surface and have the possibility to retrieve the structural parameters of the land surface;（2） the MODIS BRDF shape indicators are intrinsically three-dimensional.Since Anisotropic Index（ANIX） is highly related to Anisotropic Factor（ANIF） and has wider value range than the ANIF,the ANIF may be removed from the MODIS BRDF shape indicator products for refinement of the MODIS BRDF/Albedo products;（3） Anisotropic Flat Index（AFX） is related to basically scattering types of land surface with low within-class variances,so it is considered to be more useful in improving land cover classification accuracy.