Mobilized and Mobilizable Visibility Distances for Road Visibility in Fog

Fog is a challenging problem for road safety. To estimate the fog density and estimate the meteorological visibility distance, some attempts using an in-vehicle cameras are being developed. To complete the notion of meteorological visibility, we propose to estimate the distance to the most distant visible object belonging to the road surface. We call this distance the mobilized visibility distance, which may be compared with the mobilizable visibility distance which is defined as being the greatest distance at which a potential object on the road surface would be visible. In this paper, the relationships between these distances and the meteorological visibility distance are established. To illustrate our proposal, our methods to estimate the meteorological visibility distance and the mobilized visibility distance are presented and samples of results are given.