A method for kernel-driven model to correct the blended hemispherical diffuse irradiance in multi-angle measurements

Semi-empirical kernel-driven Bidirectional Reflectance Distribution Function (BRDF) model has been developed to retrieve the BRDF shapes of the observed surface from multi-angle measurements. At present, hemispherical diffuse irradiance is usually blended in the multi-angle measurements. The blend of diffuse irradiance will smooth the intrinsic BRDF shapes of observed surface. Therefore, there is a need to correct the diffuse irradiance to get the ideal BRDF shapes when the multi-angle measurements is processed by the kernel-driven model. In this article, we develop a method for kernel-driven model to correct the blended hemispherical diffuse irradiance in the multi-angle measurements. Multi-angle data simulated by the PROSAIL model are used to validate the efficiency of the method. The result indicates that the simulated reflectance after correction agree well with the measurements without diffuse irradiance.