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INTEGRATING AUTHORITATIVEAND VOLUNTEEREDGEOGRAPHIC INFORMATION -AN ONTOLOGICAL APPROACHCrowd SourcinginNationalMappingInternshipFundingACTIVITYWorkshopLeuven(Belgium)14thMay2013JimenaMartínezRamos[firstname.lastname@example.org]
Table of contents21. Background2. Problem3. Objective4. Proposed approach5. Semantics in OSM datasets (ongoing work)6. Conclusions and future work
Background3(*) http://ggim.un.org/ (UN Report, 2012)National Mapping Agencies (NMAs) are likely tofind difficult to justify the costs of traditionaldata maintenance mechanisms.VGI projects (like OpenStreetMap) are growingand are seen as a good data source to beintegrated with authoritative datasets.There is growing need of integrating differentdata sources.Semantic interoperability is still an issue in theintegration problem.TheneedofintegratingGeographicInformationfromdifferentsources?Levels of heterogeneitySystemSyntacticStructuralSemantic(meaning of words)
The Problem4SemanticHeterogeneityinGeographicInformationmotorwayConceptualizationturnpiketrunkConceptualizationWords or symbols standfor things through ideasDifferentconceptualizations:Semantic HeterogeneitiesOgden andRichards, 1923ConceptualizationConceptualizationReality (road)Symbol (freeway)
trunkConceptualizationThe Problem5SemanticHeterogeneityinGeographicInformationturnpikePre-processEverybody thinking thesamePost-processMatching symbols withthe same meaningSTANDARDS!ONTOLOGIES!Reality (road)ConceptualizationfreewayfreewayConceptualizationConceptualizationtrunkConceptualizationConceptualizationConceptualization
6ObjectSubjectRoadTransportation“Explicit specificationof a conceptualization”Gruber, 1993They are ways toconceptualize adomain.The ProblemWhatareontologiesabout?Class Properties (Sub)classisSubclassOfPredicateisSuperclassOf
Quebec• <highway=bus_stop>St. John´s▪ <public_transport=stop_position>9Morethanonetagperreal-worldphenomenon (synonymy)Ongoingwork:SemanticHeterogeneityin OSM datasets▪▪▪▪▪▪▪▪Number of tags per phenomenon increases with the scale, and % is important•<highway=bus_stop> ▪<public_transport=stop_position>
10Morethanonetagperreal-worldphenomenon (synonymy)Ongoingwork:SemanticHeterogeneityin OSM datasetsNumber of tags per phenomenon evolve with time, and % is still important•<highway=bus_stop> ▪<public_transport=stop_position>20062008Agreement through timeIncreasing level of agreementDecreasing level of agreement
Conclusions and future work11Proposed approach is based in a domain ontology, which allows:• Matching datasets to a common pivot (R2RML allows flexible and directmappings)• No need to know how to handle ontologies.• Reusing the mappings.Semantic Heterogeneity in OSM datasets.• Number of tags and their % of occurrence per real-world phenomenon• Time and spatial scale are factors affecting SH in OSM datasets.Future work:• Developing more the ontology.• User-friendly interface for making R2RML mappings.• Deeper study factors involved in SH in OSM datasets, trying to model it.