Histograms of gravitational slope angles for the five regions, derived from the SPC shape model (solid line) and from the SPG shape model (dashed line). The black arrow on Hathor indicates a bump on the SPG slopes distribution that must be ignored since it results from the fact that the SPG DTM includes a large part of the Hapi region that is absent from the SPC DTM. The Hapi region, which is smooth and flat, thus introduces a bias in the distribution for low-slope angles.