Bidirectional reflectance of a rough anisotropic surface

The goal of our work was to demonstrate that the usual assumptions of isotropy and symmetry of the bidirectional reflectance factor (BRF) are not valid for a specific anisotropic ground surface. Two methods illustrating this point are presented. The first method is based on goniometer measurements, and the second method uses a Monte Carlo algorithm. The results of both methods were analysed at different wavelengths and angular configurations. For the surface studied here, they showed that the BRF was significantly asymmetric with respect to the principal plane. In the extreme case, the difference between the two sides of the principal plane reached almost 30% of the mean reflectance value.