Modeling geographic co-ordinates in OWL

I am developing an ontology and need to model geographic co-ordinates (lat/long) as part of an address of a person. Geo Names was the obvious choice, but it's too large and verbose for my use, which led me to W3C Geo vocabulary (http://www.w3.org/2003/01/geo/).

It has a Point class, and lat/long/alt properties which should suffice my need. However, I am not able to find it, let alone set it as properties in Protege. Further investigation reveaved that “Point” is an rdfs:Class and "lat/long/alt" are rdf:Properties. I am guessing this is the reason why it is not showing up in Protege.

Is there a way to use these properties in an OWL ontology? Or are there other vocabularies that would let me specify geographic Points, Lines etc?

Thanks,

Solution

Assuming you are trying to open the file wgs84_pos present on the page http://www.w3.org/2003/01/geo/, it appears that the properties are using a format not understood by Protege 4.1 (plain RDF). Look at the line 143, you will see that:

<rdf:Property rdf:about="http://www.w3.org/2003/01/geo/wgs84_pos#lat">
  <rdfs:domain rdf:resource="http://www.w3.org/2003/01/geo/wgs84_pos#SpatialThing" />
  <rdfs:label>latitude</rdfs:label>
 <rdfs:comment>The WGS84 latitude of a SpatialThing (decimal degrees).</rdfs:comment>
</rdf:Property>

rdf:Property is not in the scope of OWL (too generic, in OWL properties are either object or data properties), therefore not displayed by Protege 4.1.

I advise that you re-create the ontology from scratch following the documentation on the web page and by looking at the RDF file. Just add the properties you need (should be quick), save, open the saved file and compare with the one you downloaded to see the differences.

The rough structure of the ontology made with Protege looks like this:

<?xml version="1.0"?>
  <!DOCTYPE rdf:RDF [
  <!ENTITY owl "http://www.w3.org/2002/07/owl#" >
  <!ENTITY xsd "http://www.w3.org/2001/XMLSchema#" >
  <!ENTITY rdfs "http://www.w3.org/2000/01/rdf-schema#" >
  <!ENTITY wgs84_pos "http://www.w3.org/2003/01/geo/wgs84_pos#" >
  <!ENTITY rdf "http://www.w3.org/1999/02/22-rdf-syntax-ns#" >
]>
<rdf:RDF xmlns="http://www.w3.org/2003/01/geo/wgs84_pos#"
 xml:base="http://www.w3.org/2003/01/geo/wgs84_pos"
 xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
 xmlns:wgs84_pos="http://www.w3.org/2003/01/geo/wgs84_pos#"
 xmlns:owl="http://www.w3.org/2002/07/owl#"
 xmlns:xsd="http://www.w3.org/2001/XMLSchema#"
 xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
<owl:Ontology rdf:about="http://www.w3.org/2003/01/geo/wgs84_pos#"/>

<owl:DatatypeProperty rdf:about="&wgs84_pos;lat">
    <rdfs:domain rdf:resource="&wgs84_pos;SpatialThing"/>
</owl:DatatypeProperty>

<owl:DatatypeProperty rdf:about="&wgs84_pos;long">
    <rdfs:domain rdf:resource="&wgs84_pos;SpatialThing"/>
</owl:DatatypeProperty>

<owl:Class rdf:about="&wgs84_pos;Point">
    <rdfs:subClassOf rdf:resource="&wgs84_pos;SpatialThing"/>
</owl:Class>

<owl:Class rdf:about="&wgs84_pos;SpatialThing"/>