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Geospatial Ontologies and Rules

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					Geospatial Semantic Web:
Architecture of Ontologies
                   Michael Smith
                  BBN Technologies
                    21 Jun 2006




 Adapted from a similar presentation by John Hebeler & Dave Kolas
           Presentation Overview
•   Goal of the Architecture
•   Background Concepts
•   An Example Query
•   Geospatial Ontologies
    –   Base Geospatial
    –   Domain of Interest
    –   Feature Data Source
    –   Geospatial Services
    –   Geospatial Filter (with associated Rule Support)
• Ontology Interdependence
                                                           2
                    Goal
Provide a set of ontologies that support:
  – Query using vocabulary consistent with the
    user’s perspective
  – Automatic query decomposition and
    translation
  – Discovery of appropriate data sources
  – Geospatial data interoperability that is
    transparent and useful to the user


                                                 3
           Background Info
• These ontologies were developed and
  tested in support of the OGC
  Interoperability Experiment on Geospatial
  Semantic Web
  – The ontologies reflect origins in existing OGC
    standards




                                                     4
      Background Info (cont.)
• Geography Markup Language (GML)
  – A specification for exchange of geospatial
    data
• Web Feature Service (WFS)
  – A web service definition for serving geospatial
    data.
• Filter Encoding
  – A specification for filtering results in a WFS
    query

                                                     5
          An Example Query
What airports within 50000 meters of Saint
 Louis can support a C5?
  – Data requirements dictate multiple data sources




                                                      6
     Geospatial Ontology Usage
                                         Feature
                                        Data Source
                                         Ontology


                                                 Geospatial
                Geospatial                        Services
                  Filter              WFS         Ontology
                Ontology
                           Base
Domain                   Geospatial
Ontology                  Ontology
           KB              (GML)




                                                         7
     Geospatial Ontology Usage
                                         Feature
                                        Data Source
                                         Ontology


                                                 Geospatial
                Geospatial                        Services
                  Filter              WFS         Ontology
                Ontology
                           Base
Domain                   Geospatial
Ontology                  Ontology
           KB              (GML)




                                                         8
    Base Geospatial Ontology
• Foundation for all other geospatial related
  ontologies
• Current implementation is an adaptation of
  GML




                                            9
     Geospatial Ontology Usage
                                         Feature
                                        Data Source
                                         Ontology


                                                 Geospatial
                Geospatial                        Services
                  Filter              WFS         Ontology
                Ontology
                           Base
Domain                   Geospatial
Ontology                  Ontology
           KB              (GML)




                                                        10
          Domain Ontology
• Represents the geospatial world from the
  perspective of the relevant domain
• Incoming data is mapped to this ontology
  upon entering the knowledgebase




                                             11
                 The Query
SELECT airport, city FROM
   {airport} rdf:type {c5:C5CapableAirport};
          filter:satisfiesFilter {filter},
   {filter} rdf:type {filter:DWithin};
            filter:referenceGeometry {city};
            filter:radius {“50000"^^xsd:int},
   {city} rdf:type {cities:City};
        filter:satisfiesFilter {cityFilter},
   {cityFilter} rdf:type {filter:PropertyIsLike};
               filter:property {"NAME"};
                filter:literal {"Saint Louis"}
                                                    12
     Geospatial Ontology Usage
                                          Feature
                                        Data Source
                                         Ontology


                                                 Geospatial
                Geospatial                        Services
                  Filter              WFS         Ontology
                Ontology
                           Base
Domain                   Geospatial
Ontology                  Ontology
           KB              (GML)




                                                        13
 Feature Data Source Ontology
• Represents concepts needed to describe
  features returned from a feature server
• Extends the concepts of the base
  geospatial ontology




                                            14
     Geospatial Ontology Usage
                                         Feature
                                        Data Source
                                         Ontology


                                                 Geospatial
                Geospatial                        Services
                  Filter              WFS         Ontology
                Ontology
                           Base
Domain                   Geospatial
Ontology                  Ontology
           KB              (GML)




                                                        15
 Geospatial Services Ontology
• Represents concepts relevant to a WFS’S
  capabilities document that are not directly
  expressible in OWL-S
• Must be understood by any clients calling
  the WFS




                                            16
     Geospatial Ontology Usage
                                         Feature
                                        Data Source
                                         Ontology


                                                 Geospatial
                Geospatial                        Services
                  Filter              WFS         Ontology
                Ontology
                           Base
Domain                   Geospatial
Ontology                  Ontology
           KB              (GML)




                                                        17
    Geospatial Filter Ontology
• Ontology to represent geospatial filters
• Required by the WFS client to represent
  queries
• Required by the WFS to advertise
  supported filters




                                             18
                 The Query
SELECT airport, city FROM
   {airport} rdf:type {c5:C5CapableAirport};
          filter:satisfiesFilter {filter},
   {filter} rdf:type {filter:DWithin};
            filter:referenceGeometry {city};
            filter:radius {“50000"^^xsd:int},
   {city} rdf:type {cities:City};
        filter:satisfiesFilter {cityFilter},
   {cityFilter} rdf:type {filter:PropertyIsLike};
               filter:property {"NAME"};
                filter:literal {"Saint Louis"}
                                                    19
                       GeoSWRL
Some filters require quantitative spatial calculations
   – Query decomposition may dictate that such calculations cannot
     be performed at the data source
   – This requirement can be satisfied by geospatial specific “built-in”
     relations
Standardization of filter rules and built-ins is an important
  step to interoperability

   gml : Geometry( A)  gml : Geometry( B) 
   filterb : DWithin( A, B, x) 
   filter : DWithin ( F )  filter : referenceG    eometry( F , B) 
   filter : radius( F , x)  filter : satisfiesFilter ( A, F )
                                                                       20
                    Geospatial Ontology
                      Dependencies
                                Domain
                                Ontology


                                             Geospatial
                                              Feature
                                              Ontology

         Geospatial
           Filter                                         Geospatial
         Ontology+                                         Services
                                                           Ontology
  Highlighted         Base Geospatial Ontology
ontologies must               (GML)
be agreed upon
      for                                                              21
interoperability.

				
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