Anisotropic Reflectance Correction of Satellite Imagery: Addressing Scale Dependent Topographic Effects

Keywords: anisotropic reflectance correction, topographic effects, multi-spectral imagery, mountain environments, meta-analysis, sensitivity analysis, irradiance components
Abstract Type: Paper Abstract

Abstract

Anisotropic reflectance correction (ARC) of satellite imagery is required to remove topographic effects that modulate surface reflectance recorded in mountain environments. Commonly utilized ARC methods do not account for irradiance components and atmosphere-topographic coupling. Furthermore, it is not clear which radiation-transfer parameters need to be formally accounted for. Consequently, we conducted a meta-analysis of the literature and performed a sensitivity analysis of parameters for the direct and diffuse skylight irradiance components. We found that common assumptions regarding atmospheric transmittance and point-source cast shadows versus solar disk cast shadows could not adequately account for topographic modulation Our results reveal that topographic effects govern surface irradiance variations in a synergistic way, and that assumptions, approximations and issues of ARC need to be formally addressed. Collectively, our review and analysis suggest that empirical ARC methods, cannot be used to effectively address topographic effects. Removing topographic effects from multispectral imagery will most likely require modeling efforts. More research is warranted on developing and evaluating new parameterization schemes that more accurately characterize the anisotropic nature of atmosphere-topography coupling on surface irradiance.