A model for rough surfaces

Data obtained from sized road tracks or rubber samples do not show a self-affinity behavior, and the usual fractal models such as the Fractional Brownian Motion are not in order. We propose here a much simpler model called the Random Bumps Functions, which allow to describe such surfaces with a good accuracy and a very few parameters. The validity of the model is checked using q-structure functions. Applications are made to experimental sets of data.