Large-scale bidirectional reflectance model for urban areas

A bidirectional reflectance factor (BRF) model for urban areas for pixel sizes of more than 500 m×500 m is developed. Possible applications include albedo calculation, improvement of classification, and change detection algorithms, simulated global BRF maps, and refinement of atmospheric correction algorithms. The model combines the BRF effects at several scales (street grid, intermediate-sized objects, and microscale). The authors present modeling results as well as a comparison with measured data. The basic features of the urban BRF are the hotspot and the independence of its shape from wavelength in the range 450 nm⩽λ⩽2300 nm. An analytical function that approximates the model is proposed for easy implementation and fast computation