Ontologies for the Integration of Geospatial Data

1. Ontologies for the Integration of Geospatial Data Michael Lutz Semantics and Ontologies for GI Services April 24-28, 2006 Ontologies for the Integration of Geospatial Data

2. Goals • Get an idea how ontologies can be used for the integration of geospatial data • Define a shared vocabulary for the domain of landcover classifications • Define land use classes for CORINE land cover classification • Execute simple and defined queries Ontologies for the Integration of Geospatial Data

3. Data Integration with Ontologies • Motivation: Different classification schemes (e.g. for landuse or geological categories) in different countries (e.g. A,SLO,I) or user communities • Goal: Enable users to use a familiar vocabulary and translate to other classification schemes • Approach: • Define “shared vocabulary” (aka “skeleton ontology”) • Define class definitions for each classification scheme based on shared vocabulary • Define query using the shared vocabulary or an existing classification scheme • Find similar or matching concepts for the query Ontologies for the Integration of Geospatial Data

4. based on based on Domain Ontology Ontologies for Enhanced GI Discovery Where are there areas that are suitable for creating a business park? Ontological (DL) description of the query concept “suitable for creating a business park” Hybrid Ontology Approach Query concept equivalence or subsumption Logical Reasoning Application Ontology Concepts Ontological (DL) description of the classes used in the classification ClassificationScheme 1 ClassificationScheme 2 Dataset 2 Dataset 1 Ontologies for the Integration of Geospatial Data

5. Hybrid Approach • Shared Vocabulary = One or several domain ontologies • Especially domain ontologies should be property-centered, i.e. define properties and their ranges(and domains) Shared Vocabulary (property-centered) provides vocabulary for ApplicationOntology ApplicationOntology Query define semantics for classes in Existing ClassificationScheme Existing ClassificationScheme User-defined ClassificationScheme Ontologies for the Integration of Geospatial Data

6. Use Defined Classes • Many ontologies are simple is-a hierarchies  little flexibility for adding new concepts (or queries) • To add this flexibility, properties(not classes) should be seen as the primary entities • Conceptsshould be defined using existing properties • use cardinality constraints and value restrictions to further constrain the range of a role inside concept definitions Ontologies for the Integration of Geospatial Data

7. Types of Queries • Simple Queries • Use an existing concept in one application ontology (i.e. a class in one classification system) • Look for matching (i.e. subsumed) concepts in other application ontologies • E.g. “show me all classes in your classification that correspond to my industrial complex class” • Defined Queries • Use terms from the shared vocabulary to build a user-defined query concept • Look for matching (i.e. subsumed) concepts in all application ontologies • E.g. “show me all classes in your classification that have an inclination of less than 10% and have good transport connections” Ontologies for the Integration of Geospatial Data

8. Example Application: Geological Maps Basis for engineering and hydro-geologicaldecision making • different times • different authors • different areas  different classification systems  Semantic heterogeneity Daten aus dem Kartenwerk Geologische Karte (DGK) des LAGB LSA, Geologische Grundkarte im Maßstab 1:25.000 Ontologies for the Integration of Geospatial Data

9. Goals • establish a service for semantic mapping between the different classification systems • Enable user-specific property-based queries Ontologies for the Integration of Geospatial Data

10. Ton Schluff Lagerung istGelagert Feinsand Sand 0...1 Bestandteil Mittelsand Karbonat Grobsand 1...3 0...* hatHauptbestandteile hatNebenbestandteile hatKonsistenz Konsistenz 1 Shared Vocabulary GESTEIN Ontologies for the Integration of Geospatial Data

11. k. A. istGelagert hatHauptbestandteile hatNebenbestandteile Application/Query Concept k. A. istGelagert 0...1 0...1 Grob- Schluff Kalk 1...3 0...* Löss 1 hatKonsistenz Locker Ontologies for the Integration of Geospatial Data

12. Exercise 1: Define a Shared Vocabulary • Look at the CORINE land cover classification at terrestrial.eionet.eu.int/CLC2000/classes • Pick a few classes and try to come up with • Properties that describe them • The “fillers” of these properties • Find a common superclass that can be used as a range • Find subclasses for the individual fillers • Do they form value partitions? • Try to model these properties and filler classes in OWL • What kind of information is easy to map to OWL? What is more difficult? Ontologies for the Integration of Geospatial Data

13. Exercise 2: Define Land Cover Classes • Split in 2 groups, using different land cover classification systems • CORINE • Realraumanalyse (www.uni-klu.ac.at/geo/projekte/realraum/Typen.htm) • Use common shared vocabulary • Import babyz.uni-muenster.de/ontologies/ont-skeleton.owl into a new Protégé project • Create defined classes for your classification system • Exchange results & do simple and defined queries Ontologies for the Integration of Geospatial Data

14. Importing Ontologies • Create and save a new Protégé project Import ontology Ontologies for the Integration of Geospatial Data

15. Importing Ontologies Ontologies for the Integration of Geospatial Data