An evaluation of the delta-Eddington contrast transmission model

Calculation of visible contrast transmittance using a model based on the delta-Eddington solution to the radiative transfer equation is evaluated for a variety of conditions. The approximate nature of the delta-Eddington approach for calculation of radiances is demonstrated by comparison with published results from a spherical harmonics model and a Monte Carlo model developed for visibility calculations. Results of visible contrast transmittance using the delta-Eddington model are shown to be adequate in many instances, the major discrepancies are found for lines of sight directed toward the sun and for calculations over low albedo surfaces.