3-D FOREST LIGHT MODEL

The FLIGHT model is based on Monte Carlo simulation of photon transport, and has been developed to simulate the observed reflectance response of three-dimensional vegetation canopies.

Publications should cite the following references:

• Three-dimensional forest light model using a Monte Carlo method (North, 1996)
• [LiDAR approach] A Monte Carlo radiative transfer model of satellite waveform LiDAR (North et al., 2010)
• [Fluorescence approach] Assessing the effects of forest health on sun-induced chlorophyll fluorescence using the FluorFLIGHT 3-D radiative transfer model to account for forest structure (Hernandez-Clemente et al., 2017)
• [Understory and SIF approach] Assessing the contribution of understory sun-induced chlorophyll fluorescence through 3-D radiative transfer modelling and field data (Hornero et al., 2021)

Evaluation of bidirectional reflectance is achieved by simulation of the photon free-path within a canopy representation, and simulation of the chain of scattering events incurred by a photon in its path from the source to the receiver or to its absorption. Multiple scattering between different foliage elements and with the ground is thus modelled. Foliage is approximated by structural parameters of area density, angular distribution, and size, and optical properties of reflectance and transmittance. Leaves are approximated as bi-Lambertian scatters, and the angular distribution of incident diffuse light may be modelled explicitly.