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Copyright © 2011 Open Geospatial Consortium.
The following extract presents an example declaration of an ontology.
owl:Ontology rdf:about =
owl:versionInfo rdf:datatype
= http:www.w3.org2001XMLSchemastring
0.3 owl:versionInfo
dc:date rdf:datatype
= http:www.w3.org2001XMLSchemada
te 2011-08-04
dc:date dc:description
rdf:datatype =
http:www.w3.org2001XMLSchemastr ing
Topographic Data Store Geodatabase Schema: This geodatabase schema defines the logical content for
Topographic Feature Data in the U.S. National System for Geospatial-Intelligence NSG.
dc:description dc:title
NGA TDS ontology dc:title
owl:imports rdf:resource
= http:env032011.appspot.comgeosparql.
rdf
owl:Ontology rdf:RDF
The following extract presents an example representation of a feature type.
owl:Class about =
http:metadata.dod.milmdrnsGSIP3.0tds3.0RailwayGeocurve
rdfs:label xml:lang
= en
Railway Geospatial Curve rdfs:label
rdfs:subClassOf resource
= http:env032011.appspot.comgeosparql.rdfFeature
rdfs:subClassOf owl:Restriction
owl:onProperty resource
= http:env032011.appspot.comgeosparql.rdfdefaultGeometry
owl:allValuesFrom resource
= http:env032011.appspot.comgeosparql.rdfCurve
owl:Restriction rdfs:subClassOf
dc:description datatype =
http:www.w3.org2001XMLSchemastring Railway
Geospatial Curve: One or more railway tracks comprising a network that is operated for the conveyance of passengers andor goods
dc:description dc:relation datatype
= http:www.w3.org2001XMLSchemaanyURI
urn:ogc:ows8:cci:topicCategory:Transportation dc:relation
rdfs:isDefinedBy rdf:resource
= owl:Class
The following extract presents an example representation of a feature property.
owl:DatatypeProperty about =
http:metadata.dod.milmdrnsGSIP3.0tds3.0 RailwayGeocurve.facilityOperationalStatus
rdfs:label xml:lang
= en
Railway Geospatial Curve : Facility Operational Status rdfs:label
dc:description datatype =
http:www.w3.org2001XMLSchemastring Railway Geospatial Curve : Facility Operational Status:
The status of operation of a facility, as a whole. dc:description
Copyright © 2011 Open Geospatial Consortium.
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skos:definition resource
= http:metadata.dod.milmdrnsGSIP3.0tds3.0
RailwayFacilityOperationalStatusType
rdfs:domain resource
= http:metadata.dod.milmdrnsGSIP3.0tds3.0
RailwayGeocurve
rdfs:range resource
= http:www.w3.org2001XMLSchemastring
owl:DatatypeProperty
The following extract presents an example representation of a codelist.
skos:ConceptScheme about =
http:metadata.dod.milmdrnsGSIP3.0tds3.0 RailwayFacilityOperationalStatusType
type resource
= http:www.w3.org200207owlThing
skos:prefLabel datatype =
http:www.w3.org2001XMLSchemastring Railway Facility Operational Status Type
skos:prefLabel skos:definition datatype
= http:www.w3.org2001XMLSchemastring
Railway Facility Operational Status Type: A coded domain value denoting the facility operational status type of a railway.
skos:definition skos:ConceptScheme
The following extract presents an example representation of a codelist value.
skos:Concept about =
http:metadata.dod.milmdrnsGSIP3.0tds3.0 RailwayFacilityOperationalStatusType_continuous
type resource
= http:www.w3.org200207owlThing
skos:prefLabel datatype =
http:www.w3.org2001XMLSchemastring Continuous
skos:prefLabel skos:definition datatype
= http:www.w3.org2001XMLSchemastring
Continuous: Operating without interruption. skos:definition
skos:altLabel datatype =
http:www.w3.org2001XMLSchemastring continuous
skos:altLabel skos:inScheme
resource =
http:metadata.dod.milmdrnsGSIP3.0tds3.0 RailwayFacilityOperationalStatusType
skos:Concept
Clients querying the SPARQL server were then able to compose queries based on the following example:
SELECT ?property ?codelist ?codelistValue ?codelistValueLabel
WHERE { ?property http:www.w3.org200001rdf-schemadomain http:metadata.dod.milmdrnsGSIP3.0tds3.0RailwayGeocurve
. ?property http:www.w3.org200402skoscoredefinition ?codelist . ?codelistValue
http:www.w3.org200402skoscoreinScheme ?codelist . ?codelistValue http:www.w3.org200402skoscoreprefLabel
?codelistValueLabel}
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Copyright © 2011 Open Geospatial Consortium.
9 Semantic Mappings
Upon reviewing the feature types from the source datasets, it was observed that there potentially would be a variety of mapping scenarios for feature types. These included:
No mapping: source feature type has no suitable match in target One-to-one: source feature type has one suitable match in target; all instances of the
source feature type should be mapped as instances of the target feature type One-to-many: source feature type matches with more than one target feature type. In
this case, the value of one or more properties determines which the target feature type is for a certain source instance
Many-to-One: source feature type matches with one target feature type. However, there are other source feature types that also map to that target feature type. When
transforming data from source to target, one or more properties should get a fixed value.
Similarly it was observed that feature properties would exhibit similar mapping scenarios. These included:
Direct mapping: the property value of the source feature is directly used as the property value of the target feature
No mapping: the source property has no suitable match in the target feature type Codelist mapping; Between codelists it was also observed that there could be:
o Direct value mapping: one source code list value maps directly on one target
code list value o
No mapping: source code value has no suitable value in the target code list. In order not to lose information, the recommendation seems to be to put the
value of the source code in some free TXT attribute if available of the target type
o Many-to-one : multiple source code list values are mapped on a single target
code list value
9.1 Ontology Mapping versus Transformation Rules
