[OSM-talk] Naga City in OSM Re: GML to OSM

[Andy Allan]

On Thu, Apr 10, 2008 at 9:24 AM, Lester Caine <lester at lsces.co.uk> wrote:

>  Looking at the growing mess of wiki pages relating to
>  place/is_in/boundary/relations and the rest I think that I would not be
>  wasting my time now putting together a 'proposal' for good practice for
>  handling the simple hierarchy of is_in but it does need a means of identifying
>  different 'Naga City' objects other than adding 'Camarines Sur, Luzon,
>  Philippines' to every use of it :(

is_in is a short-term kludge. It's almost completely unnecessary when
- and only when - we have boundaries for whatever the larger area is.
Sometimes it's useful* when you don't.

The key fact that everyone forgets is that everything we deal with has
geographic coordinates. If you can give me a bounding polygon for a
country (whether derived from OSM or VMAP0 or wherever) then I can
tell you if a given amenity=pub is in that country. No need for any
relations or is_in tags AT ALL.

If we weren't talking about map data, then yes, we'd need a hierarchy.
organisation=society,name=RNIB would need is_in=UK, for example, since
there can't be coordinates for something that doesn't have a physical
location. But we're not worried about that because we're talking about
OpenStreetMap.

If you want a list of islands in the Philippines, it's really quite
straightforward. Give all the islands coastlines, define the boundary
of the country, and hey presto the rest is just a SELECT statement. If
you want to tag every island, ney every node in the database with what
regions they lie within (via is_in or relations) then you're wasting
your time.

Cheers,
Andy

* Not sure to who, to be honest, but maybe the namefinder uses it?