[geos-devel] Problems creating polygons with holes

Martin Davis mbdavis at VividSolutions.com
Wed Jun 30 11:30:14 EDT 2004


You can model this situation with a MultiPolygon.

I think you'd find if you worked out the details that allowing Polygons
to be holes would create all sorts of strange situations that the code
would have to handle.  Besides, if there's an application that really
needs this they can fairly easily create helper code to provide the ring
components in the way GEOS needs them.

Martin Davis, Senior Technical Architect
Vivid Solutions Inc.      www.vividsolutions.com
Suite #1A-2328 Government Street Victoria, B.C. V8T 5G5
Phone: (250) 385 6040 - Local 308 Fax: (250) 385 6046


> -----Original Message-----
> From: Norman Vine [mailto:nhv at cape.com] 
> Sent: June 30, 2004 8:23 AM
> To: GEOS Development List
> Subject: RE: [geos-devel] Problems creating polygons with holes
> 
> 
> > 
> > > I had assumed that the holes were treated as polygons as well :(
> > 
> > If polygon holes were defined by polygons, then your holes 
> could have 
> > holes
> > (which in turn could have holes...)!
> 
> not so far fetched ..
> 
> ie. an island in a pond in an island in a lake in an island 
> in the ocean :-)
> 
> < assuming a hole in a water polygon is land and visa versa >
> 
> Norman
> 
> 
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