Rahman

This is a semi-empirical model with 3 parameters, designed to model the reflectance of arbitrary natural surfaces in the visible and near-infrared bands.

This is one of eight BRDF kernels listed by Spurr in his 2002 paper.

Equation A.18 from Spurr is implemented with the following changes:

• cos(phi) is replaced with -cos(phi)

• the reflectance is divided by pi

Example

import sasktranif.sasktranif as skif
import math

brdf = skif.ISKBrdf('RAHMAN')
mjd            = 52393.3792987115;
location       = [0.0, 0.0, 25000.0, mjd];
[ok,brdfvalue] = brdf.BRDF( 600.0, location, 0.6, 0.7, -0.8)

Properties

BRDFParameters

BRDF_RAHMAN.BRDFParameters(array param)

A 3 element array containing the 3 parameters of the Rahman distribution.

n	Setting
parameters[0]	\(\rho\)
parameters[1]	\(\theta\)
parameters[2]	\(k\)

References

Rahman H, Pinty B, Verstraete M. “Coupled surface atmosphere reflectance (CSAR) model: 2. Semi-empirical surface model usable with NOAA AVHRR data.”, J Geophys Res 1993; 98:20,791–801.

Robert J. D. Spurr, “A new approach to the retrieval of surface properties from earthshine measurements”, Journal of Quantitative Spectroscopy & Radiative Transfer, vol. 83, pp. 15-46, Oct. 9, 2002. doi:10.1016/S0022-4073(02)00283-2 url: http://www.sciencedirect.com/science/article/pii/S0022407302002832