Estimation of canopy bidirectional reflectance by using Bidirectional Reflectance Simulator (BiRS)

Abstract

Bidirectional reflectances obtained from optical satellite sensor is effective for the estimation of vegetation quantity (e.g., above ground biomass) because biomass is related to canopy shape and the information of that canopy shape can be obtained by bidirectional reflectance. The relationships between bidirectional reflectance and canopy shape have been modeled in several studies. However, it is extremely difficult to measure the input parameters (e.g., leaf area index, leaf inclination angle) of those models in the field. Therefore, the bidirectional reflectance predicted by those models does not match with the bidirectional reflectance observed over the canopy. On the other hand, the bidirectional reflectance obtained at top of canopy by airborne or spaceborne platform is affected by limited observation geometry. In this study, we developed bidirectional reflectance simulator (BiRS) which can simulate bidirectional reflectance in any arbitrary observation geometry. BiRS can estimate bidirectional reflectance using digital surface model (DSM) and top of canopy bidirectional reflectance obtained by radio controlled helicopter.