[geos-devel] Simplifying adjacent polygons

Bill Zissimopoulos geos at billz.fastmail.fm
Wed Mar 19 14:05:27 EDT 2008

Hello, list:

I am looking for a method to correctly simplify adjacent polygons
without leaving gaps between them or having them intersect after the
simplification. Currently my simple algorithm iterates over my
geometries and feeds them to GEOSTopologyPreserveSimplify separately;
obviously this is inadequate.

Is it possible to correctly simplify adjacent polygons in GEOS? One
technique I have been thinking about is to construct a multi-geometry
with all the geometries in my dataset and pass this multi-geometry to
GEOSTopologySimplify. Even if this worked, I would have to identify the
individual geometries in the resulting multi-geometry since they
represent different features in the original dataset. For example, a
lake polygon and a land polygon next to it would have to be identified
again after simplification so they can be properly rendered.

The solution here might be to abuse slightly the z coordinate to store
tagging information about individual polygons. But I wanted to hear any
comments from the experts on the list before I attempt this.

Your comments will be very much appreciated.


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