A windows graphic user interface (GUI) for the five‐scale model for fast BRDF simulations

In recent years, the computational power of personal computers (PC) has increased to the point that computationally‐demanding research can now be achieved on low cost PC machines. Furthermore, portable laptops allow heavy computational science to be carried out anywhere, even during field measurements. The radiative‐transfer models Four‐scale (Chen and Leblanc, 1997; Leblanc et al, 1999; Chen and Leblanc, 2000) and LIBERTY (Dawson et al., 1998), which were both originally coded in C, have been combined to form a five scales model. This new Five‐scale model was adapted to the Windows environment with a Graphic User Interface (GUI) to facilitate its usage. The software allows the Bidirectional Reflectance Distribution Functions (BRDF) to be computed and plotted in real‐time in four different ways: (1) customised planes (e.g., principal plane) of different spectral reflectances and components such as the probabilities of seeing sunlit and shaded foliage and background; (2) a hemispherical mode to view reflectance at all angles at once; (3) a hyperspectral mode that uses reflectivity spectra of foliage and background to compute the canopy reflectance under a specific view‐target‐sun geometry; and (4) a user‐defined mode that allows the user to specify changes in any parameters such as Leaf Area Index (LAI) for studying vegetation indices and other canopy properties. The simulations can be saved in ASCII format for importing to other software. This interface is a good tool for studying radiative transfer in vegetation for various remote sensing applications. The usefulness of the model as a learning tool and advantages of the model for the study of multiangular measurements are presented.