Not sure why this is labeled a Voronoi diagram, it might be for some set of points but none are there. The algorithm mentioned in the blurb is MDSCAL, googling around finds various references including this survey paper

http://people.sabanciuniv.edu/berrin/cs512/reading/camastra-...

It is labeled Voroni diagram because the actual map is a Voroni diagramm of the points placed by the algorithm, clipped to some outline.