Abstract
Synopsis.—In this paper the hypothesis is put forward that a road surface behaves as a system of an infinite number of polished facets, the orientation of which varies according to certain distribution laws, and the reflection factor of which depends on the angle of reflection. An experiment is described which suggests the existence of such a system of facets. It is shown that experimental results can be conveniently and sufficiently accurately expressed in terms of this hypothesis; and there follows a rapid method for plotting isobrightness contours on the perspective image of a road which is illuminated by a light source of known polar distribution. A qualitative explanation is also given of the changes in light reflecting properties of a surface which can be observed with progressive wear and polish, or with wetting.
Get full access to this article
View all access options for this article.