///<summary>
/// Returns the boundary, or the empty geometry if this Geometry is empty.
///</summary>
///<remarks>For a discussion
/// of this function, see the OpenGIS Simple Features Specification. As stated in SFS
/// Section 2.1.13.1, "the boundary of a Geometry is a set of Geometries of the next lower dimension."</remarks>
///<returns>Returns the closure of the combinatorial boundary of this Geometry.</returns>
public override Geometry GetBoundary()
{
if ( IsEmpty() )
{
return _geometryFactory.CreateGeometryCollection( null );
}
GeometryGraph g = new GeometryGraph(0, this);
Coordinates pts = g.GetBoundaryPoints();
return _geometryFactory.CreateMultiPoint(pts);
}
