EVALUATIONS OF THE SIGHTING DISTANCE IN A FOGGY ATMOSPHERE BY MONTE-CARLO SIMULATION

A code for the simulation of light propagation in multiple scattering media is presented. Unlike the analytical methods which generally requ ire simplifying assumptions, the MUSCAT (MUltiple SCATtering) code onl y needs general assumptions, namely steady-state and scalar radiative transfer. Knowing the 3D-geometrical and photometrical characteristics of sources and detectors and the albedo, extinction coefficient and p hase function of the scattering medium, the code computes what will be detected. A concrete application is presented: the sighting distance of a foglight in a foggy night atmosphere is evaluated for a real driv ing situation. The road is perfectly absorbent and two cases are compa red: the road is lit either by a headlight or by one-sided street lamp s. The sighting distance of a 60% reflexive target is also computed an d the same comparison is done.