[OpenStreetMap talk-lu] OSM database interface

Thu Dec 6 07:57:20 GMT 2012

Hi,

I like the idea. That would definitely be a good extension of the 
current system. The implementation itself wouldn't be such a big 
problem, but the computation costs (point in polygon, browsing the 
database etc.) are quite large compared to the bbox approach. A combined 
approach could help though. I will write it on my list and will see what 
I can do

Frank

Am 2012-12-05 20:26, schrieb Loll:
> Hi
>
> I do not know if it's possible to make/program, but here one idea. It
> would be great if one could use this data interface not only with a
> bounding box but also with other limits like administrative boundaries
> (districts, canton, communes).
>
> CU
> Laurent
>
> Frank Broniewski said the following on 05/12/2012 08:54:
>> Just a few working examples for you to try out.
>>
>> http://www.gis-hosting.lu/osm2web/export/points/amenity/restaurant.geojson?bbox=70503,69758,84957,80518&srid=2169
>>
>> all restaurants in Luxembourg city
>>
>> http://www.gis-hosting.lu/osm2web/export/lines/waterway/river.geojson?bbox=70503,69758,84957,80518&srid=2169
>>
>> rivers in Luxembourg city
>>
>> http://www.gis-hosting.lu/osm2web/export/polygons/leisure/park.geojson?bbox=70503,69758,84957,80518&srid=2169
>>
>> parks in Luxembourg city
>>
>> I guess this might help trying things out ;-)
>>
>> Frank
>>
>>
>>
>>
>>
>> Am 2012-12-04 08:55, schrieb Frank Broniewski:
>>> Hi all,
>>>
>>> I've developed an read-only interface to our OSM world database and I
>>> want to contribute this to the community in order to give something
>>> back.
>>>
>>> It's a simple interface, as you can query features by key=value or by
>>> OSM id. There're plans for a query language which allows broader queries
>>> but I haven't started yet. Where're using the interface in our
>>> OpenLayers Webapps and it's easy to integrate the URL as a Layer in
>>> OpenLayers. Several outputformats are supported, namely GeoJSON, GML,
>>> KML and GPX.
>>>
>>> Things are best explained by example:
>>>
>>> Query for restaurants:
>>> http://www.gis-hosting.lu/osm2web/export/points/amenity/restaurant.geojson
>>>
>>> Query for motorways:
>>> http://www.gis-hosting.lu/osm2web/export/lines/highway/motorway.geojson
>>> Query for restaurants:
>>> http://www.gis-hosting.lu/osm2web/export/polygons/landuse/forest.geojson
>>>
>>> ... you get the idea: http://www.gis-hosting.lu/osm2web/export is a
>>> fixed part of the URL, the next part tells about the geometry type you
>>> want to retrieve, and the next two parts are the well known key=value
>>> combinations from the map features page in the OSM wiki. The file
>>> extension after the value part tells what kind of format you want to
>>> retrieve. Simply add any of the above mentioned output formats in lower
>>> case as file extension.
>>>
>>> A mandatory parameter is a bounding box (bbox=minx,miny,maxx,maxy) in
>>> order to limit the region of the query. At the moment I only check if
>>> the parameter is set, but I don't check the size. So you could go ahead
>>> and download all restaurants in the world -  but I *strongly* discourage
>>> that. So please keep your bounding box small. Downloading all
>>> restaurants in Luxembourg isn't a deal though ...
>>>
>>> There's one more thing I'd like to mention. We support all coordinate
>>> systems in the well known Proj4 database. So if you want LUREF
>>> coordinates, pass srid=2169 as an additional parameter. As a convenience
>>> feature, the bounding box needs to have the same CRS as the srid. The
>>> default srid is 3857, which is also the srid for the databases native
>>> CRS. So you can pass in the the srid as an additional query param to
>>> OpenLayers, add the BBOX Strategy and you're ready to go:
>>>
>>> var layer = new OpenLayers.Layer.Vector(
>>>      'Restaurants in LUREF',
>>>      {
>>>          'strategies': [
>>>              new OpenLayers.Strategy.BBOX()
>>>          ],
>>>          'protocol': new OpenLayers.Protocol.HTTP({
>>>              'url':
>>> 'http://www.gis-hosting.lu/osm2web/export/points/amenity/restaurant.geojson',
>>>
>>>
>>>              'format': new OpenLayers.Format.GeoJSON(),
>>>              'params': { 'srid': 2169 }
>>>          })
>>>      }
>>> );
>>> You probably need to set OpenLayers.ProxyHost [2] in order to use the
>>> layer like this
>>>
>>> The other URL I implemented takes a geometry type - any of points,
>>> lines, polygons - and an OSM id as parameter and returns exactly one
>>> feature.
>>> http://www.gis-hosting.lu/osm2web/export/points/id/1887429277.gpx for
>>> example is a hotel in Cape Verde. This URL doesn't take any additional
>>> parameters and returns the data always in WGS84 coordinate reference
>>> system.
>>>
>>> You'll get the full osm2pgsql schema, that means probably a lot of empty
>>> values in your attributes. But that's difficult to change right now. In
>>> the future I want to enhance the application further. The most important
>>> thing for me right now is a enhanced query language and SRID/EPSG
>>> support for the export by OSM id, but I don't have a timeline set up. I
>>> also plan on caching features retrieved from the database in order to
>>> speed up the deliverance through the web.
>>>
>>> There's a bitbucket repo at [1] where any changes should show up.
>>>
>>> I hope you'll find this project useful. Any feedback, positive or
>>> negative, or any questions are welcome.
>>>
>>>
>>> Thanks for reading the email up to the end :-),
>>>
>>> Frank
>>>
>>>
>>>
>>>
>>>
>>> [1] https://bitbucket.org/metrico/osm2web
>>> [2]
>>> http://trac.osgeo.org/openlayers/wiki/FrequentlyAskedQuestions#ProxyHost
>>
>>
>
>
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Frank BRONIEWSKI

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