Photometric model and roughness characterization for 3D micro textures analysis

Car road holding is linked to many factors including adherence, which is strongly related to the roughness of the road coating and of its evolution under the effect of traffic. Traffic induces a progressive wear of the road surface which results in a modification of its local relief and of its roughness. We study road coverings in order to know the variations of their wear levels over time by analyzing the micro texture of these road images. The transcription of roughness criteria in image analysis requires, on one hand, the development of a photometric model for the coating surface, and, on the other hand, a modeling of the profile of the road coating. The method suggested in this article is based on a photometric model of the surface of the coating from which we study the statistical properties of : the distribution of the gray levels in the image, the distribution of the absolute value of its gradient, and the form of its autocorrelation function. Experiments have been done with images of road coverings at different wear levels. The obtained results are similar to those obtained by a direct method of contact measuring.