Seminar

Surface roughness is a key property of soils that controls many surface processes and influences the scattering of incident electromagnetic waves at a wide range of scales. The Hapke photometric model provides an approximate analytical solution of the Bidirectional Reflectance Distribution Function (BRDF) of a particulate medium: the effect of surface roughness is introduced as a correction factor of the BRDF of a smooth surface. This photometric roughness is defined as the mean slope angle of the facets composing the surface, integrated over all scales from the grain size to the local topography. Yet its physical meaning is still a question at issue, as the scale at which it occurs is not clearly defined. This talk sums up recent research works that aimed at better understanding the relative influence of roughness scales on soil BRDF and to test the ability of the Hapke model to retrieve a roughness parameter that depicts effectively the ground truth, both on simulated and experimental remote sensing data.