A concise characterization of 3D simple points Original Research Article

We recall a possible definition of a simple point which uses the digital fundamental group introduced by Kong (Comput. Graphics 13 (1989) 159). Then, we prove that a more concise but not less restrictive definition can be given. Indeed, we prove that there is no need to consider the fundamental group of the complement of an object in order to characterize its simple points. In order to prove this result, we do not use the fact that “the number of tunnels of X is equal to the number of tunnels in X̄” but we use the linking number defined in (Proceedings of the Seventh International Workshop on Combinatorial, Image Analysis (IWCIA’00), University of Caen, 2000, p. 59). In so doing, we formalize the proofs of several results stated without proof in the literature (Bertrand, Kong, Morgenthaler).