Realization of Field BRDF Acquisition by Multiangular Measurement System

In order to acquire field Bidirectional Reflectance Distribution Function (BRDF) of targets, a multiangular measurement system was designed. The system includes an automated goniometer and two ASD FieldSpec spectroradiometers with spectral resolution of 3nm. One ASD spectroradiometer was placed on the platform of goniometer measured reflectance of target, meanwhile, the other placed on the ground acquired reflectance of reference panel. We measured the BRDF of meadow by use of this system. A hemispherical measurement (66 positions) was done in about 10 minutes and the principal plane measurement (interval 5°,31 positions) was carried out in about 2.5 minutes. The measurement results show the non-Lambertian characters of the target, which exposes obvious directional reflectance in principal plane with strong back-scattering and a less developed forward scattering.