The Delaunay triangulation of a spatial point pattern X
is defined as follows. First the Dirichlet/Voronoi tessellation
based on X is computed; see dirichlet. This
tessellation is extended to cover the entire two-dimensional plane.
Then two points of X
are defined to be Delaunay neighbours if their Dirichlet/Voronoi tiles
share a common boundary. Every pair of Delaunay neighbours is
joined by a straight line to make the Delaunay triangulation.
The result is a tessellation, consisting of
disjoint triangles. The union of these triangles is the convex hull of
X.