It is interesting to compare our results with the ones pre- viously obtained by Kreslavsky et al. (2008). They have calculated a measure of roughness for Lunar Highlands using Lunar Pro- spector data, for Mars highlands and northern plains using MOLA data, and for Mercury using Earth-based radar observations. Their choice of a roughness measure different from the MDS was dictated by the low vertical accuracy of the topographic data for Mercury. While the spatial resolution of these datasets does not allow estimating the roughness at spatial scale lower than about 40 km, there is a range of baselines, 40 to 100 km, on which we can compare our roughness estimates. Results seem to be in very good agreement as the ratios of roughness between the highlands regions of the three planets are similar: 3 for the Moon/Mercury and 1.5 for Mercury/Mars at a baseline of 100 km.