[OSM-talk] Administrative boundaries export

César Martínez Izquierdo cesar.izq at gmail.com
Thu Oct 3 13:17:27 UTC 2013


The important issue here is that there is lots of potential uses here
(layers are not used exclusively for creating "maps", they can also be used
for analysis) and there are people wishing to use these datasets: the
administrative boundaries based on coastline (call them whatever you want),
the ones based on the territorial waters, and possible others.

Because of this reason, it would be useful to have them explicitly mapped
on OSM. It is not the same to just extract a relation and descendants and
build some polygons from there, than to extract the coastline and the
borders that are not coastline and try to see how they fit within their
containing country. It is feasible, but not practical.

However, as you suggested, it is important to keep an eye on
maintainability of OSM data when creating these relations. A simple
approach would be to create land mass relations having other relations as
members. For instance, in Spain such relationship could be easily created
from the admin_level=4 relations, containing just 19 members (as subareas).
As far as the admin_level=4 relations are correct, the superrelation should
be correct (if not, they should be corrected anyway). I don't know if such
approach would be so feasible for other countries. Of course, proper
tagging should be applied to these relations in order to don't create
ambiguities.

César


2013/10/3 Martin Koppenhoefer <dieterdreist at gmail.com>

>
> 2013/10/3 Pieren <pieren3 at gmail.com>
>
>> All the states or countries maps I've seen in my life used the
>> coastline. It does not mean that the sovereignty stops at the water
>> line. It's just a convention.
>>
>
>
> how many states or country maps have you seen in scale 1:1000?
>
> cheers,
> Martin
>
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   César Martínez Izquierdo
   GIS developer
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   Universitat Autònoma de Barcelona (SPAIN)
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