The small bodies of the Solar System have unique individual shapes that need to be considered when selecting an approximating mathematical reference surface and subsequent mapping. The authors examine the problem of choosing an appropriate ellipsoid for mapping binary celestial bodies, typically formed by the merging of two previously separate objects. Their complex “dumbbell” or “bean” shape previously led to the idea of mapping them as two separate celestial objects. However, a quantitative assessment of how well they are approximated by two reference surfaces versus a single one has not been conducted yet. We propose an analytical approach based on comparing the mathematical statistics of the height distribution relative to a triaxial ellipsoid on raster digital elevation model images, for mapping using one versus two reference surfaces. The object is the asteroid 25143 Itokawa, which had previously been considered a body with a less pronounced binary shape and approximated by a single ellipsoid