Dimensionally Extended Nine-Intersection Model (DE-9IM)

Abstract

The Dimensionally Extended Nine-Intersection Model (DE-9IM) or Clementini-Matrix is specified by the OGC “Simple Features for SQL” specification for computing the spatial relationships between geometries. It is based on the Nine-Intersection Model (9IM) or Egenhofer-Matrix which in turn is an extension of the Four-Intersection Model (4IM). The Dimensionally Extended Nine-Intersection Model considers the two objects’ interiors, boundaries and exteriors and analyzes the intersections of these nine objects parts for their relationships (maximum dimension (-1, 0, 1, or 2) of the intersection geometries with a numeric value of –1 corresponding to no intersection). The spatial relationships described by the DE-9IM are “Equals”, “Disjoint”, “Intersects”, “Touches”, “Crosses”, “Within”, “Contains” and “Overlaps”.