[postgis-users] How to design a database for continents, countries, regions, cities and POIs?

Jerry Carter jerry at jerrycarter.org
Wed Apr 11 08:55:41 PDT 2012

Thanks for the quick answer.  Just read your writeup on the subject [1].  This looks like a _very nice_ addition and should be extremely helpful.  I've got some experimenting to do!

-=- Jerry

[1] http://strk.keybit.net/projects/postgis/Paris2011_TopologyWithPostGIS_2_0.pdf

In otherwords, you skip
On Apr 11, 2012, at 11:51 AM, Sandro Santilli wrote:

> On Wed, Apr 11, 2012 at 11:47:02AM -0400, Jerry Carter wrote:
>> I might have a geometry for a country and separate geometries for the
>> next layer of administrative regions (e.g. states in the United States).
>> But there are often minor differences in the polygons such that the
>> polygon for the country is nearly but not exactly the union of the states.
>> How is this handled?
> In the topology model your higher layer will be defined by composition
> of lower layer items. So you would only say that "United States" is
> formed by all the countries. And for each country you would only list
> the counties they are formed of. And for each county the parcels.
> And for each parcel the primitive faces. And each face is defined by
> its edges.
> The only actual geometries involved in all of the above would be
> the edge geometries. Not any other geometry. So there's no difference
> because primitive elements are singletons.
> --strk;
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