Unified characterization of P-simple points in triangular, square, and hexagonal grids

Abstract

Topology preservation is a crucial property of topological algorithms working on binary pictures. Bertrand introduced the notion of P -simple points on the orthogonal grids, which provides a sufficient condition for topology-preserving reductions. This paper presents both formal and easily visualized characterizations of P -simple points in all the three types of regular 2D grids.