The digitization of the skeleton is the source of many difficulties. The
skeleton of a binary set can be defined as the set of crest points and their
upstream on the distance function10, 12. The final result depends on the
quality of the distance function which has been used. The result is particularly coarse with the hexagonal distance function. The use of an euclidean distance function yields a beautiful skeleton, once some subtle interactions with the grid have been solved.
"Digital Euclidean skeletons", Proc. SPIE 1360, Visual Communications and Image Processing '90: Fifth in a Series, (1 September 1990); doi: 10.1117/12.24212; https://doi.org/10.1117/12.24212