Universität Leipzig ▪ Agile Knowledge Engineering and Semantic Web (AKSW) Authors: Sören Auer, Jens Lehmann, Claus Stadler Slide 1 Linked (Geo) Data Adding a Spatial Dimension to the Web of Data Claus Stadler, Sören Auer AKSW Research Group University of Leipzig http://linkedgeodata.org
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Linked (Geo) Data - Adding a Spatial Dimension to the Web of Data
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Universität Leipzig ▪ Agile Knowledge Engineering and Semantic Web (AKSW) Authors: Sören Auer, Jens Lehmann, Claus Stadler Slide 1
Linked (Geo) DataAdding a Spatial Dimension to the Web of Data
Claus Stadler, Sören Auer AKSW Research Group University of Leipzig
Universität Leipzig ▪ Agile Knowledge Engineering and Semantic Web (AKSW) Authors: Sören Auer, Jens Lehmann, Claus Stadler Slide 2
Structure
● Linked Data● LinkedGeoData
● Architecture● Mapping to RDF/OWL● Interlinking● Applications● Issues & Future work
● Open Governmental Geo Data
Universität Leipzig ▪ Agile Knowledge Engineering and Semantic Web (AKSW) Authors: Sören Auer, Jens Lehmann, Claus Stadler Slide 3
The emerging Web of Linked Data
Universität Leipzig ▪ Agile Knowledge Engineering and Semantic Web (AKSW) Authors: Sören Auer, Jens Lehmann, Claus Stadler Slide 4
Universität Leipzig ▪ Agile Knowledge Engineering and Semantic Web (AKSW) Authors: Sören Auer, Jens Lehmann, Claus Stadler Slide 5
LinkedGeoData
Conversion, interlinking and publishing of OpenStreetMap.org data sets as RDF.
Universität Leipzig ▪ Agile Knowledge Engineering and Semantic Web (AKSW) Authors: Sören Auer, Jens Lehmann, Claus Stadler Slide 6
Motivation
● Ease information integration tasks that require spatial knowledge, such as
● Offerings of bakeries next door● Cinemas nearby and their programs● Historical sights along a bicycle track
● Therefore use RDF/OWL in order overcome structural and semantic heterogeneity.
● LOD cloud contains data sets with spatial features● e.g. GeoNames, DBpedia, US census, EuroStat● But: they are restricted to popular or large entities like countries, famous
places etc.● OSM offers buildings, roads, mailboxes, trash bins/recyling, ...
Universität Leipzig ▪ Agile Knowledge Engineering and Semantic Web (AKSW) Authors: Sören Auer, Jens Lehmann, Claus Stadler Slide 7
What do we offer?
● Very large RDF knowledge base derived from OpenStreetMap
● REST API, static & live SPARQL endpoints
● Update propagation of the added and removed triples
● 845.000 Interlinks with DBpedia, GeoNames, and FAO
● LGD-Browser
Universität Leipzig ▪ Agile Knowledge Engineering and Semantic Web (AKSW) Authors: Sören Auer, Jens Lehmann, Claus Stadler Slide 8
Architecture
Universität Leipzig ▪ Agile Knowledge Engineering and Semantic Web (AKSW) Authors: Sören Auer, Jens Lehmann, Claus Stadler Slide 9
OpenStreetMap - Datamodel
● Basic entities are:● Nodes Latitude, Longitude
● Ways Sequence of nodes
● Relations Associations between any number of nodes, ways and relations.
● Each entity may be described with tags:
key-value pairs, such as (amenity, school)
Universität Leipzig ▪ Agile Knowledge Engineering and Semantic Web (AKSW) Authors: Sören Auer, Jens Lehmann, Claus Stadler Slide 10
Example: Leipzig's Zoo
Universität Leipzig ▪ Agile Knowledge Engineering and Semantic Web (AKSW) Authors: Sören Auer, Jens Lehmann, Claus Stadler Slide 11
OSM entities → RDF
● Three types of mappings based on (osm-id, key, value)
Universität Leipzig ▪ Agile Knowledge Engineering and Semantic Web (AKSW) Authors: Sören Auer, Jens Lehmann, Claus Stadler Slide 23
Issues & Future work
● Converting all OSM data to RDF not feasible:
> 1.000.000.000 nodes
→ only a subset of OSM's data available via the SPARQL endpoints
● Virtuoso only supports point geometries
● Possible solution: Rewriting SPARQL queries to the OSM SQL schema● Work in progress, no estimate on a release yet
Universität Leipzig ▪ Agile Knowledge Engineering and Semantic Web (AKSW) Authors: Sören Auer, Jens Lehmann, Claus Stadler Slide 24
Issues and Future Work
● Investigating further applications of LGD, such as using the LGD knowlegde base for named entity recognition/resolution
Universität Leipzig ▪ Agile Knowledge Engineering and Semantic Web (AKSW) Authors: Sören Auer, Jens Lehmann, Claus Stadler Slide 25
Open Governmental Geo Data
● Most governmental data has a spatial dimension● transportation, statistics, finances, etc.
● Geo Data is a driver in the Open Government Data realm● ordenance survey, geodata.gov.gr, …
● It is still difficult to extract, publish, interlink, author and visualize Governmental Linked Geo Data● LOD2 Stack (ckan integration, browsing widgets,
integrated comprehensive tool compilation)
Universität Leipzig ▪ Agile Knowledge Engineering and Semantic Web (AKSW) Authors: Sören Auer, Jens Lehmann, Claus Stadler Slide 26
Best practices
● Reuse of vocabularies
● vCard: address information, phone & fax
● Good Relations: Opening hours, product descriptions