[postgis-users] Simplify a perfect (hierarchical) partition of polygons (ST_SimplifyPreserveTopology and friends)

Sandro Santilli strk at keybit.net
Wed Mar 14 02:34:50 PDT 2012

On Wed, Mar 14, 2012 at 10:11:13AM +0100, William Humphrey Temperley wrote:

> I recently did this for the Global Administrative Unit Layers (GAUL) stored
> in PostGIS using the simplify polygon tools in ArcGIS.  Whilst I'd love to
> use the new topology tools Sandro has developed, this wasn't practical at
> this time.
> The steps I took were:
> 1. Simplify the smallest (admin2) units using the Simplify Polygon tool,
> asking it to resolve topological errors.
> 2. Dissolve the generalized polygons on their parent id 
> 3. Repeat 2 until I arrived at admin0 
> Each time I had to reload the new geometries back into PostGIS.

You missed this step:
 0. buy an ArcGIS license.

> Will Temperley
> Spatial Database Developer
> Land Resource Management Unit
> European Commission - Joint Research Centre

You know I've been working at the JRC for 1 year ?
Had to wait to get out of there in order to bring some love
to the PostGIS topology support. Not a single euro was spent
by the EC on it. Not even a slot of the pledge [1] was taken.

[1] http://pledgebank.com/postgistopology

On the other hand milions are spent by JRC on Oracle and ESRI
licenses so I guess "practical" is really a subjective matter.


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