[OSM-dev] Is there any API to get data from OSM as geoJson?

[Martin Raifer]

Hello Stefan

I mentioned client side generation of GeoJSON from OSM data as an  
alternative to a "central GeoJSON API" approach (which API is not  
available yet; see below).

As always, it depends on the actual use case. When your application has  
its own geo database already, it's probably best to implement the GeoJSON  
export there. On the other hand, when you handle only few data from a  
source that provides only OSM data (like the main API or Overpass API), it  
doesn't really matter where you do the conversion. Or, if you are not  
interested in displaying "live" (minutely updated) data, it may be best  
not to bother any API on each request at all and do the conversion  
beforehand.

That said, the original question for a "central GeoJSON API" is a more  
complicated issue, as the conversion from OSM to GeoJSON is not always  
trivial. An OSM object can be a LineStrings or a (Multi)Polygon in GeoJSON  
depending on context! E.g. one can interpret an administrative boundary as  
a border line [LineString] or the containing area [Polygon]. It gets even  
more non-trivial for some of the more abstract relation types (turn  
restrictions, enforcements, etc.). That said, it may be possible to write  
such a GeoJSON API, but it must consider these contexts in some way.

Btw: I think you are mistaken when it comes to Overpass API: it does *not*  
return GeoJSON or any GeoJSON like geometry (LineStrings, etc.) [1]. Where  
did you see ways as LineStrings as a response from Overpass?

Cheers,
Martin

[1]  
http://overpass-turbo.eu/?Q=%3Cosm-script%3E%0A%20%20%3Cunion%3E%0A%20%20%20%20%3Cquery%20type%3D%22way%22%3E%0A%20%20%20%20%20%20%3Chas-kv%20k%3D%22cuisine%22%20v%3D%22pizza%22%2F%3E%0A%20%20%20%20%20%20%3Cbbox-query%20%7B%7Bbbox%7D%7D%2F%3E%0A%20%20%20%20%3C%2Fquery%3E%0A%20%20%20%20%3Crecurse%20type%3D%22way-node%22%2F%3E%0A%20%20%3C%2Funion%3E%0A%20%20%3Cprint%2F%3E%0A%3C%2Fosm-script%3E&C=47.39803;8.61975;18&R  
(go to "data" tab)


Am 10.02.2013, 02:06 Uhr, schrieb Stefan Keller <sfkeller at gmail.com>:

> To Martin and Ander:
> Martin suggested to use Overpass output. He also pointed to
> OSM4Leaflet.js which does resolve node id's in ways to linestrings.
> I would avoid such client-side calculations (except perhaps it's about
> an editor or admin too) since this can be done on server-side.
> But I think Overpass can already do that:
> [...]
> The response includes nodes and ways (which are eal GeoJSON
> linestrings) because  of the "magic" recurse syntax.