Checks that a
GeometryGraph representing an area
(a
Polygon or
MultiPolygon )
has consistent semantics for area geometries.
This check is required for any reasonable polygonal model
(including the OGC-SFS model, as well as models which allow ring self-intersection at single points)
Checks include:
test for rings which properly intersect
(but not for ring self-intersection, or intersections at vertices)
test for consistent labelling at all node points
(this detects vertex intersections with invalid topology,
i.e.