[Talk-us] Towns as Areas or Points

[Emilie Laffray]

On 31 August 2010 11:36, Serge Wroclawski <emacsen at gmail.com> wrote:

> As so often happens in OSM, a small mystery turns into a big question,
> so here's mine for the week:
>
> If you don't want the explanation, just skip down to the part where it
> says "THE QUESTION".
>
> I live in a place called Silver Spring, Maryland.
>
> It's not prominently displayed on the map: http://osm.org/go/ZZcfj5yN-
>
> Yet Takoma Park, which is much smaller, does.
>
> It turns out the reason is that the node for this town is:
> http://nominatim.openstreetmap.org/details.php?place_id=437409
>
> And has the tag hamlet.  Silver Spring is not a hamlet. It has about
> 80,000 people living in it according to
> http://en.wikipedia.org/wiki/Silver_Spring,_Maryland
>
> My initial thought was "Well we should change the point", but then I
> discovered this relation:
> http://www.openstreetmap.org/browse/relation/133501
>
> Which seems better (it still says that SS is a locality, which is
> essentially the same as a hamlet/village, but it at least has the
> administrative boundaries).
>
> THE QUESTION
>
> Do I fix the node? Do I copy the tags from the node into this relation
> and then fix the relation?
>
> Why was the node the thing that came up in nominatim searches, and not
> the relation?
>
> If I remove this node, will bad things happen?
>

In theory, nothing wrong will happen if you delete the point. The place
value should be probably changed in both cases. In terms of rendering,
Mapnik will create a center of gravity point for the polygon. Essentially
you will end up with two names displayed on the map.
In France, we keep the two systems, a point and a relation for marking a
town. The main reason is that the point can be used to reflect what the
proper center of the town is.
I don't think Nominatim rates locality very high compared to an hamlet. I
can tell you that at work, we are ignoring place=locality for our reverse
geocoding.

Emilie Laffray
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