Changes on data collection scale influencing the bidirectional reflectance distribution function

Abstract

Comparing remote sensing data acquired at different data acquisition geometries is commonly carried out considering the angular dependencies of the electromagnetic radiation reflection described by the bidirectional reflectance distribution function (BRDF). Thus, this function is assumed to be invariant for any acquisition level (laboratory, field, airborne and orbital), which here will be treated as “scale”. We characterized the BRDF of three surfaces with different superficial characteristics, using 1◦, 8◦ and 25◦ field-of-view (FOV) optics to simulate different acquisition levels to investigate feasible influences on radiometric quantities by changing scales. Measurements of reflectance quantities were performed using a goniometer developed by the Laboratório de Radiometria e Caracterização de Sensores Eletro-ópticos (LaRaC) of the Instituto de Estudos Avanc¸ados (IEAV). The results showed that depending on surface characteristics, different BRDF behaviors can be observed according to the viewing optics. In general, surface BRDF obtained by 8◦ and 25◦ FOVs showed very similar behaviors and values. On the other hand, surface BRDF obtained by 1◦ FOV were comparable to the obtained with others FOV only in the case of a flat surface. © 2017 Sociedade Brasileira de Geof´ısica