RE: GeoNames and Spatial Queries

Christopher St John wrote:

> I'm looking for feedback/pointers on best practices for 
> finding objects in the Linked Data cloud given a geographic 
> area of interest.

Currently the only mainstream RDF triplestore I am aware of that does
efficient spatial indexing is Allegrograph (http://agraph.franz.com/).
Of course this would involve loading your spatial RDF into a local
triple store. Personally I would like to see the spatial datatypes
provided as part of the GML spec
(http://en.wikipedia.org/wiki/Geography_Markup_Language) put on an equal
footing as other XML datatypes which would at least provide a standard
(along with the work done here http://www.w3.org/2005/Incubator/geo/) on
which tool developers could build. This would all SPARQL queries like

select ?s ?o
where
{
	?s hasGeom ?g1
	?o hasGeom ?g2
	FILTER (TOUCH(?g1,?g2)= true)
}

However, I don't think the problem of spatial indexing over the linked
data web is going to be solved any time soon. We (at OS) think a lot of
traction can be gained from developing gazetteers in RDF with
topological relationships between geographic regions
(http://www.ordnancesurvey.co.uk/oswebsite/ontology/
http://os.rkbexplorer.com/) (Dbpedia, geonames and freebase all do
similar things as well). At least then you can ask queries like "find me
all pubs in England", "Find me hotels in Hampshire and cities bordering
Hampshire" without the need for geometries or spatial indexing.

Not sure if that answers your question...

John
.


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Received on Wednesday, 25 February 2009 09:07:33 UTC