It is interesting to note that, due to the different shapes of the MDS curves, the highlands of Mercury appear smoother than the lunar highlands at baselines larger than 2 km but rougher at shorter baselines. Mars southern plateaus are significantly smoother than Hermian and Lunar highlands at any baseline. There are many mechanisms that can lead to such differences in the scale dependent roughness characteristics of the different planets. They are mainly related to the cratering history of the surface, to the bulk physical properties of the planetary body, and to the alteration of topography by weathering. Because of the difference of size, composition, position in the Solar System, presence or absence of an atmosphere between the Moon, Mars, and Mercury, it is difficult to distinguish the relative influence of these different parameters on the scale-dependent roughness.