Comparisons of three models for vegetation canopy bi-directional reflectance distribution function

Aims With the development of quantitative remote sensing technology, multiple bi-directional reflectance dis- tribution function (BRDF) models have been developed to describe reflectance of forest canopies. Our objective is to compare the DART, 4SCALE and MGEOSAIL models for greater understanding their proper use. Methods We used the BRDF models to simulate reflectance of the scene with different canopy densities at various observation angles in red and near-infrared bands and compared the results to analyze model applicability and limitations. Important findings The MGEOSAIL model is suitable to simulate the scene reflectance with low canopy den- sity and large trees, and the hotspot is obvious. The DART and 4SCALE models are accurate and suitable to simulate the scene reflectance with various kinds of canopy density. Also, the scene reflectance simulated by 4SCALE is higher than DART's simulated first-order scattering value, but lower than DART's fifth-order scat- tering value. All three models show the "bowl" shape in the near-infrared band.