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Re: Geo in RDF (was Re: Censorship?)

From: Stuart Williams <skw@epimorphics.com>
Date: Mon, 15 Nov 2010 14:26:03 +0000
Message-ID: <4CE142FB.5010609@epimorphics.com>
To: bvillazon@fi.upm.es
CC: public-egov-ig@w3.org
Hello Boris,

On 13/11/2010 15:11, Boris Villazón Terrazas wrote:
> Hi Stuart
> We recently exchanged some emails, thanks to Michael Hausenblas.
Indeed we did...
> However, this is my first post this mailing list.
> I only want to point out our ongoing work in the context of the GeoLinkedData 
> [1], in which  we are working with geospatial data. Basically, we are using 
> geo:lat/geo:long style of giving position in WGS84 coordinates. A geospatial 
> resource, for example a geoes:Provincia, has a geo:geometry, and this 
> geo:geometry consists of a set of geo:points , and each geo:point consists of 
> geo:lat and geo:long. You can find a figure describing this at [2].
I've got a minor question wrt to the use of geoes:order in the diagram at [2]. 
It seems to be giving the ordinal position of a Point in a LineString. It seems 
to me that there isn't a single value of geoes:order which applies to a given 
point... it depends on what LineString the point is being included in.
> A specific example, the resource Albacete Provincia at [3].
> Also, we have a browser at [4].
> I think this is related with the discussion.
> We can provide further information regarding the conversion from GML to RDF we 
> performed.

I think that the details of your conversion are fairly clear in your 
presentation at http://www.slideshare.net/boricles/geo-upmv14boris

What I am looking for is a *widely* adopted practice, perferably backed/endorsed 
by a defacto or de-jure standards organisation. I don't think I have found such 
a beast except for the case of Point positions expressed as WGS 84 lat/long in 
which case there is widespread community practice in the use of the "Basic Geo 
(WGS84 lat/long) Vocabulary" [a].
[a] http://www.w3.org/2003/01/geo/

For curves (LineStrings), surfaces(Polygons) and  Boxes (Envelopes), the Geo OWL 
vocabulary at [b,c] which mirrors GeoRSS GML [d] seems to me to come close to 
being something that a common practice might develop around, however it does 
'camp' in an opengis.org namespace without obvious endorsement from the OGC 
(unless I missed finding that, which is perfectly possible).

[b] http://www.w3.org/2005/Incubator/geo/XGR-geo-20071023/#owl
[d] http://www.georss.org/gml#GeoRSS_GML

I think Gannon was making a point about localized re-invention of vocabulary 
either being inevitable or maybe accidental - either way it mitigates against 
the widespread adoption of a common practice and potentially linits the reuse of 
data assets published using a particular local practice. It also mitigates 
against tooling, developing to support such things as spatial-indexes in SPARQL 
stores, because without the use of common vocabularies you loose the triggers 
that would induce index building - and responsive UIs seeking to display 
artefacts within spatial bounding boxes could well do with the help a spatial 
index could give.

> Best
> Boris Villazón-Terrazas
> geo: http://www.w3.org/2003/01/geo/wgs84_pos#
> [1]: http://geo.linkeddata.es/
> [2]: http://mccarthy.dia.fi.upm.es/challenge/example1.png
> [3]: http://geo.linkeddata.es/page/resource/Provincia/Albacete
> [4]: http://geo.linkeddata.es/browser/



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Received on Monday, 15 November 2010 14:26:46 UTC

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