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

William Humphrey Temperley william.temperley at jrc.ec.europa.eu
Wed Mar 14 06:09:30 PDT 2012

> -----Original Message-----
> From: Sandro Santilli [mailto:sandro.santilli at gmail.com] On Behalf Of
> Santilli
> Sent: 14 March 2012 10:35
> To: PostGIS Users Discussion
> Cc: William Humphrey Temperley
> Subject: Re: [postgis-users] Simplify a perfect (hierarchical) partition
> polygons (ST_SimplifyPreserveTopology and friends)
> 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.
> 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
> 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
> guess "practical" is really a subjective matter.

Yep I did know you were working here at the JRC :)  

Chances are the OP (Martin Tomko) has an Arc license available as he's in an
academic institution.

Practical means "getting stuff done" in my book.  Open source is always my
first port of call, but I won't conform to a religion.  I'm looking forward
to trying out your topology work - but when it's practical to do so!

I agree it is a shame that it is rare for open source software to be funded
by public institutions, especially when even small change for them would
make a difference.  I can't comment on the EC stance on this.



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