The reason for this differential contrast of roughness at different baselines is certainly related to the fact that on all studied planetary objects, the topography at large scale is essen- tially the result of ancient processes (large impacts craters and ejecta emplaced early in the history of the Solar System), while the topography at shorter scale is susceptible to be also affected by contemporary processes such as small scale impact cratering, weathering of the surface by solar wind and micrometeorites in the case of the Moon and Mercury or atmospheric erosion in the case of Mars.