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

[Roland Olbricht]

Hello Stefan,

> That's what I conclude from [1] i.e. <osm-script output="json">  ...
> </osm-script>

The format option "JSON" meets the format described here:
http://wiki.openstreetmap.org/wiki/Xappy.js

This has exactly the same semantics like OSM XML and only different syntax. 
However, JSON makes some JavaScript applications a lot easier than XML, so I 
followed the suggestion to add it.

What makes me hesitate about GeoJSON is essentially that there is no clear 
rule whether an elements becomes a linestring or a polygon. Solving this will 
require both a test for validness (e.g. self intersections, but also some 
other corner cases. Most are listed on
http://wiki.openstreetmap.org/wiki/Multipolygon#Valid_Multipolygon_conditions
) as well as a semantic interpretation of tags.

The most likely mid-term solution is to convert ways always to linestrings, 
but the area type to polygons. This has the advantage that both the code to 
validate polygons and the choice of tags is done by code that does this anyway 
for area creation.

I will code this proper together with a area output implementation conforming 
to Jochen's outline
http://blog.jochentopf.com/2012-11-26-an-area-datatype-for-osm.html
so it will take some time until it gets available. I expect it is complete 
some weeks before the FOSSGIS conference, together with a couple of other 
larger changes.

Cheers,

Roland