integrating authoritative and volunteered geographic information - an ontological approach crowd...
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INTEGRATING AUTHORITATIVE AND VOLUNTEERED GEOGRAPHIC INFORMATION -
AN ONTOLOGICAL APPROACH
Crowd Sourcing in National Mapping Internship Funding
ACTIVITY Workshop
Leuven (Belgium)14th May 2013Jimena Martínez Ramos [jmr125@mun.ca]
2
Table of contents
1. Background
2. Problem
3. Objective
4. Proposed approach
5. Semantics in OSM datasets (ongoing work)
6. Conclusions and future work
Background
3
(*) http://ggim.un.org/ (UN Report, 2012)
National Mapping Agencies (NMAs) are likely to find difficult to justify the costs of traditional data maintenance mechanisms.
VGI projects (like OpenStreetMap) are growing and are seen as a good data source to be integrated with authoritative datasets.
There is growing need of integrating different data sources.
Semantic interoperability is still an issue in the integration problem.
The need of integrating Geographic Information from different sources
?
Levels of heterogeneity
System
Syntactic
Structural
Semantic (meaning of words)
4
The ProblemSemantic Heterogeneity in Geographic Information
motorway
Conceptualization
turnpike
trunk
Conceptualization Words or symbols stand for things through ideas
Different conceptualizations:
Semantic Heterogeneities
Ogden and Richards, 1923
ConceptualizationConceptualization
Reality (road)Symbol (freeway)
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trunk
Conceptualization
The ProblemSemantic Heterogeneity in Geographic Information
turnpike
Pre-processEverybody thinking the same
Post-processMatching symbols with the same meaning
STANDARDS!ONTOLOGIES!
Reality (road)
Conceptualization
freewayfreeway
Conceptualization
Conceptualization
trunkConceptualization
ConceptualizationConceptualization
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ObjectSubject
RoadTransportation
“Explicit specification of a conceptualization” Gruber, 1993
They are ways to conceptualize a domain.
The ProblemWhat are ontologies about?
Class Properties (Sub)class
isSubclassOf
Predicate
isSuperclassOf
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Ontology3
Dataset 2turnpike
Dataset 1Freeway
Ontology2
Ontology1
?
ObjectiveUsual approach to geodata integration using ontologies
Turnpike =
motorway
Freeway=
motorway
Freeway+ Turnpike
= motorway
Freeway+ Turnpike
motorwayCommon Standard
conceptualization
Interoperable datasets
Ontology and Standard approach to semantic integration
VGI(OSM)motorway
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motorwaytrunk
freeway
Official source 1
turnpike
Proposed ApproachThe method according the objectives
“turnpike”
“freeway”
#user 1: “trunk”
#user n: “motorway”
R2RMLmapping
R2RMLmapping
“motorway”
“moto
rway”
R2RMLmapping
RDF
RDF
RDF
StandardDomain
Ontology
RealityCommon
Knowledge
“motorway”
Official source 1
OpenStreetMap
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Quebec • <highway=bus_stop>
St. John´s
▪ <public_transport=stop_position>
More than one tag per real-world phenomenon (synonymy)
Ongoing work: Semantic Heterogeneity in OSM datasets
▪▪▪
▪▪▪
▪▪
Number of tags per phenomenon increases with the scale, and % is important
• <highway=bus_stop> ▪ <public_transport=stop_position>
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More than one tag per real-world phenomenon (synonymy)
Ongoing work: Semantic Heterogeneity in OSM datasets
Number of tags per phenomenon evolve with time, and % is still important
• <highway=bus_stop> ▪ <public_transport=stop_position>
2006
2008
Agreement through timeIncreasing level of agreementDecreasing level of agreement
Conclusions and future work
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Proposed approach is based in a domain ontology, which allows:
• Matching datasets to a common pivot (R2RML allows flexible and direct mappings)
• 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.
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Thank you. Gracias.Questions? AGILE/EuroSDR
NSERC
TU Delft
IGN Spain
Sinfogeo Ltd.
Dr. Jean BrodeurDrs. Marian de VriesMarine and Geomatics Lab colleagues
<amenity=plane>
Acknowledgements
PNOA aerial images. IGN Spain Icons by http://dryicons.com Jimena Martinez [jmr125@mun.ca]
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