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Invited talk on at http://www.isi.edu
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LinkedGeoData and GeoKnow
Claus Stadler Jens Lehmann
2013-09-19
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 1 / 55
Outline
1 Motivation for LinkedGeoData
2 OpenStreetMap
3 LinkedGeoData Architecture
4 Sparqlify and Tag Mappings
5 Access and Statistics
6 Use Cases
7 GeoKnow Project Overview
8 GeoKnow Achievements
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 2 / 55
Outline
1 Motivation for LinkedGeoData
2 OpenStreetMap
3 LinkedGeoData Architecture
4 Sparqlify and Tag Mappings
5 Access and Statistics
6 Use Cases
7 GeoKnow Project Overview
8 GeoKnow Achievements
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 3 / 55
Motivation
Ease information integration tasks that require spatial knowledge,such as
O�erings of bakeries next doorMap of distributed branches of a companyHistorical sights along a bicycle track
LOD cloud contains data sets with spatial features
e.g. Geonames, DBpedia, US census, EuroStatBut: they are restricted to popular or large entities like countries,famous places etc. or speci�c regions
Therefore they lack buildings, roads, mailboxes, etc.
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 4 / 55
Outline
1 Motivation for LinkedGeoData
2 OpenStreetMap
3 LinkedGeoData Architecture
4 Sparqlify and Tag Mappings
5 Access and Statistics
6 Use Cases
7 GeoKnow Project Overview
8 GeoKnow Achievements
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 5 / 55
OpenStreetMap - Datamodel
Basic entities are:
Nodes Latitude, Longitude.Ways Sequence of nodes.Relations Associations between any number of nodes, ways andrelations. Every member in a relation plays a certain role.
Each entity may be described with tags (= key-value pairs)
A way is closed if the ID of the last referenced node equals that of the�rst one.
Whether a closed way denotes a linear ring or a polygon (i.e. whetherthe enclosed area is part of the respective OSM entity) depends on thetags.
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 6 / 55
Example: Leipzig's Zoo
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 7 / 55
Comparison: Leipzig's Zoo (OpenStreetMap)
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 8 / 55
Comparison: Leipzig's Zoo (GoogleMaps)
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 9 / 55
Outline
1 Motivation for LinkedGeoData
2 OpenStreetMap
3 LinkedGeoData Architecture
4 Sparqlify and Tag Mappings
5 Access and Statistics
6 Use Cases
7 GeoKnow Project Overview
8 GeoKnow Achievements
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 10 / 55
LGD Architecture
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 11 / 55
Tag Mappings
Key-value pairs will be assigned toRDF ressources
Each pair (k , v) can be annotated withdatatypes, language tags, classes
Mappings are themselves tables
Example table:lgd_map_literal
k property lang
name rdfs:labelname:en rdfs:label enalt_label skos:altLabelnote rdfs:comment. . . . . . . . .
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 12 / 55
View De�nition
RDF mapping of the data from aPostgreSQL database
Create View lgd_nodes As
Construct {
?n a lgdm:Node .
?n geom:geometry ?g .
?g ogc:asWKT ?o .
}
With
?n = uri(lgd:node, ?id)
?g = uri(lgd-geom:node, ?id)
?o = typedLiteral(?geom, ogc:wktLiteral)
From
nodes
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 13 / 55
Sparqlify
SPARQL-SQL Rewriter
Rewrites SPARQL Queries accordingto the view de�nitionPlatform module o�ers SPARQLEndpoint and Linked Data interface
https:
//github.com/AKSW/Sparqlify
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 14 / 55
Rest-API
O�ers REST methods for frequentqueries
Based on SPARQL (Virtuoso) endpoint
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 15 / 55
Downloads
RDF dataset for download
Generated usingConstruct { ?s ?p ?o }
http:
//downloads.linkedgeodata.org
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 16 / 55
Outline
1 Motivation for LinkedGeoData
2 OpenStreetMap
3 LinkedGeoData Architecture
4 Sparqlify and Tag Mappings
5 Access and Statistics
6 Use Cases
7 GeoKnow Project Overview
8 GeoKnow Achievements
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 17 / 55
SML Mapping Examples
The following slides demonstrate how to map relational data to RDFwith the Sparqli�cation Mapping Language (SML).
Thereby, these pre�xes are used:Pre�xes
pre�x IRI
rdfs http://www.w3.org/2000/01/rdf-schema#
ogc http://www.opengis.net/ont/geosparql#
geom http://geovocab.org/geometry#
lgd http://linkedgeodata.org/triplify/
lgd-geom http://linkedgeodata.org/geometry/
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 18 / 55
SML - Mapping Example I: The Goal (1/4)
Input Table
nodesid geom
1 POINT(0 0)2 POINT(1 1)
How to map tables to RDF?
How to introduce thecommonly useddistinction in GIS betweenfeature and geometry?
Aimed for RDF Output
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
...
lgd:node1 geom:geometry lgd-geom:node1 .
lgd:node2 geom:geometry lgd-geom:node2 .
lgd-geom:node1 ogc:asWKT "POINT(0 0)"^^ogc:wktLiteral .
lgd-geom:node2 ogc:asWKT "POINT(1 1)"^^ogc:wktLiteral .
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 19 / 55
SML - Mapping Example I: SML Syntax Outline (2/4)
Input Table
nodesid geom
1 POINT(0 0)2 POINT(1 1)
Create View myNodesView As
Construct {
...
}
With
...
From
...
Aimed for RDF Output
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
...
lgd:node1 geom:geometry lgd-geom:node1 .
lgd:node2 geom:geometry lgd-geom:node2 .
lgd-geom:node1 ogc:asWKT "POINT(0 0)"^^ogc:wktLiteral .
lgd-geom:node2 ogc:asWKT "POINT(1 1)"^^ogc:wktLiteral .
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 20 / 55
SML - Mapping Example I: Construct and From (3/4)
Input Table
nodesid geom
1 POINT(0 0)2 POINT(1 1)
Create View myNodesView As
Construct {
?n geom:geometry ?g .
?g ogc:asWKT ?o
}
With
...
From
nodes
Aimed for RDF Output
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
...
lgd:node1 geom:geometry lgd-geom:node1 .
lgd:node2 geom:geometry lgd-geom:node2 .
lgd-geom:node1 ogc:asWKT "POINT(0 0)"^^ogc:wktLiteral .
lgd-geom:node2 ogc:asWKT "POINT(1 1)"^^ogc:wktLiteral .
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 21 / 55
SML - Mapping Example I: Complete! (4/4)
Input Table
nodesid geom
1 POINT(0 0)2 POINT(1 1)
Create View myNodesView As
Construct {
?n geom:geometry ?g .
?g ogc:asWKT ?o
}
With
?n = uri(lgd:node, ?id)
?g = uri(lgd-geom:node, ?id)
?o = typedLiteral(?geom,
ogc:wktLiteral)
From
nodes
Aimed for RDF Output
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
...
lgd:node1 geom:geometry lgd-geom:node1 .
lgd:node2 geom:geometry lgd-geom:node2 .
lgd-geom:node1 ogc:asWKT "POINT(0 0)"^^ogc:wktLiteral .
lgd-geom:node2 ogc:asWKT "POINT(1 1)"^^ogc:wktLiteral .
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 22 / 55
SML Mapping Examples
A more complex example, which demonstrates the use of an SQLmapping table and an SQL helper view.
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 23 / 55
SML - Mapping Example II: The Goal (1/8)
Input Table
node_tagsid k v
1 name Universitaet Leipzig1 name:en University of Leipzig1 amenity university1 addr:street Augustusplatz1 addr:city Leipzig
Aimed for RDF Output
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix lgd: <http://linkedgeodata.org/triplify/> .
lgd:node1 rdfs:label "Universitaet Leipzig" .
lgd:node1 rdfs:label "University of Leipzig"@en .
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 24 / 55
SML - Mapping Example II: Source Data (2/8)
OSM Table
node_tagsid k v
1 name Universitaet Leipzig1 name:en University of Leipzig1 amenity university1 addr:street Augustusplatz1 addr:city Leipzig
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 25 / 55
SML - Mapping Example II: Mapping Table (3/8)
OSM Table RDF Mapping Table
node_tagsid k v
1 name Universitaet Leipzig1 name:en University of Leipzig1 amenity university1 addr:street Augustusplatz1 addr:city Leipzig
lgd_map_literalk property lang
name rdfs:labelname:en rdfs:label enalt_label skos:altLabelnote rdfs:comment. . . . . . . . .
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 26 / 55
SML - Mapping Example II: Helper View (4/8)
OSM Table RDF Mapping Table
node_tagsid k v
1 name Universitaet Leipzig1 name:en University of Leipzig1 amenity university1 addr:street Augustusplatz1 addr:city Leipzig
lgd_map_literalk property lang
name rdfs:labelname:en rdfs:label enalt_label skos:altLabelnote rdfs:comment. . . . . . . . .
Helper View
lgd_node_tags_literalid property v lang
1 rdfs:label Universitaet Leipzig1 rdfs:label University of Leipzig en. . . . . . . . . . . .
SELECT id, property, v, lang FROM node_tags, lgd_map_literal
WHERE node_tags.k = lgd_map_literal.k
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 27 / 55
SML - Mapping Example II: SML View (5/8)
Logical Table SML View
lgd_node_tags_literalid property v lang
1 rdfs:label Univ. L.1 rdfs:label Univ. of L. en. . . . . . . . . . . .
Create View lgd_node_tags_text As
Construct {
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 28 / 55
SML - Mapping Example II: SML View (6/8)
Logical Table SML View
lgd_node_tags_literalid property v lang
1 rdfs:label Univ. L.1 rdfs:label Univ. of L. en. . . . . . . . . . . .
Create View lgd_node_tags_text As
Construct {
?s ?p ?o .
}
With
...
From
lgd_node_tags_literal
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 29 / 55
SML - Mapping Example II: SML View (7/8)
Logical Table SML View
lgd_node_tags_literalid property v lang
1 rdfs:label Univ. L.1 rdfs:label Univ. of L. en. . . . . . . . . . . .
Create View lgd_node_tags_text As
Construct {
?s ?p ?o .
}
With
?s = uri(lgd:node, ?id)
?p = uri(?property)
?o = plainLiteral(?v, ?lang)
From
lgd_node_tags_literal
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 30 / 55
SML - Mapping Example II: SML View (8/8)
Logical Table SML View
+lgd_node_tags_literal
id property v lang
1 rdfs:label Univ. L.1 rdfs:label Univ. of L. en. . . . . . . . . . . .
Create View lgd_node_tags_text As
Construct {
?s ?p ?o .
}
With
?s = uri(lgd:node, ?id)
?p = uri(?property)
?o = plainLiteral(?v, ?lang)
From
lgd_node_tags_literal
Resulting RDF
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix lgd: <http://linkedgeodata.org/triplify/> .
lgd:node1 rdfs:label "Universitaet Leipzig" .
lgd:node1 rdfs:label "University of Leipzig"@en .
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 31 / 55
Further Tag Mappings
decide datatype based on key:lgd_map_dataypek datatype
seats integerunisex boolean
decide property: based on key:lgd_map_property
k property
website foaf:homepage
decide predicate and object based on key (e.g. class assertion):lgd_map_resource_kk property object
highway rdf:type lgdo:HighwayThing
decide predicate and object based on key and value:lgd_map_resource_kvk v property object
waterway river rdf:type lgdo:River
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 32 / 55
LGD Edit Tool
Automatic heuristics for mappings
+ Multi user tag mapping web application for manual re�nements
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 33 / 55
Ontology
Lightweight: taxonomy + domain/range axioms
1200+ classes
Enriched classes and properties with multilingual labels fromTranslateWiki
http://translatewiki.net
Imported icons for 90 classes from the freely available iconcollection from the SJJB Management
http://www.sjjb.co.uk/mapicons/
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 34 / 55
Outline
1 Motivation for LinkedGeoData
2 OpenStreetMap
3 LinkedGeoData Architecture
4 Sparqlify and Tag Mappings
5 Access and Statistics
6 Use Cases
7 GeoKnow Project Overview
8 GeoKnow Achievements
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 35 / 55
Resources
Sparqlifyhttp://sparqlify.org
LinkedGeoDatahttp://linkedgeodata.org
Tag Mappingshttps://github.com/GeoKnow/LinkedGeoData/blob/master/linkedgeodata-core/src/main/resources/org/aksw/linkedgeodata/sql/Mappings.sql
SML View De�nitionshttps://github.com/GeoKnow/LinkedGeoData/blob/master/linkedgeodata-core/src/main/resources/org/aksw/linkedgeodata/sml/LinkedGeoData-Triplify-IndividualViews.sml
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 36 / 55
Statistics (15 August 2013)
Complete OSM planet �le corresponds to ∼ 20.000.000.000 triples
Virtual access via SparqlifyFull download: ca. 120 GB bz2 compressed (ca. 2.5 TB uncompressed)2.7 MB ontology
Downloads for important fragments available (no roads etc.):292.780.188 Triples
153.613.243 triples of Nodes139.166.945 triples of WaysRelations not yet available for download
Among them
532.812 PlaceOfWorship82.788 RailwayStation72.091 Toilets71.613 Town19.937 City
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 37 / 55
Access
Materialized Sparql Endpoint (based on Virtuoso DB, downloaddatasets loaded)
http://linkedgeodata.org/sparql
http://linkedgeodata.org/snorql
Virtual Sparql Endpoint (based on Sparqlify, access to 20B triples,limited SPARQL 1.0 support)
http://linkedgeodata.org/vsparql
http://linkedgeodata.org/vsnorql
Rest Interface (based on the Virtual Sparql Endpoint)
Supports limited queries (e.g. circular/rectangular area, �ltering bylabels)
Downloads
http://downloads.linkedgeodata.org
Monthly updates on the above datasets envisioned
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 38 / 55
Outline
1 Motivation for LinkedGeoData
2 OpenStreetMap
3 LinkedGeoData Architecture
4 Sparqlify and Tag Mappings
5 Access and Statistics
6 Use Cases
7 GeoKnow Project Overview
8 GeoKnow Achievements
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 39 / 55
Use Cases Augmented Reality
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 40 / 55
Use Cases Generic Browsing
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 41 / 55
Use Cases Generic Browsing
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 42 / 55
App Generation
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 43 / 55
Event Management
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 44 / 55
Outline
1 Motivation for LinkedGeoData
2 OpenStreetMap
3 LinkedGeoData Architecture
4 Sparqlify and Tag Mappings
5 Access and Statistics
6 Use Cases
7 GeoKnow Project Overview
8 GeoKnow Achievements
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 45 / 55
Project Overview
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 46 / 55
Outline
1 Motivation for LinkedGeoData
2 OpenStreetMap
3 LinkedGeoData Architecture
4 Sparqlify and Tag Mappings
5 Access and Statistics
6 Use Cases
7 GeoKnow Project Overview
8 GeoKnow Achievements
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 47 / 55
Achievements - Linked Data Stack
Many SW tools support one ormore life-cycle stages
Linked Data Stack (http://stack.linkeddata.org)provides a consolidatedrepository of such tools
Each tool is a Debian package
Lightweight integration betweentools via common vocabulariesand SPARQL
Demonstrator interfaces forshowing tools in combination
Developed by LOD2 andGeoKnow
Interlinking/ Fusing
Classifi-cation/
Enrichment
Quality Analysis
Evolution / Repair
Search/ Browsing/
Exploration
Extraction
Storage/ Querying
Manual revision/
Authoring
Linked DataLifecycle
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 48 / 55
Achievements - Benchmarking
Intensive work on benchmarking geospatial systems
�Slippy map benchmark� for standard web map applications and otherbenchmarks to follow
State of the Art Analysis for Triple Stores performed (Virtuoso,uSeekM, Parliament, AllegroGraph, OWLIM-SE, Strabon + OracleSpatial 11g, PostGIS as reference) using fragments of OSM andOrdnance Survey data
High deviation in performance and supported functionality betweengeospatial triple stores
GeoSPARQL compliance not achieved yet
More speci�c results to be published throughout the project . . .
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 49 / 55
Achievements - Sparqlify
SPARQL-SQL rewriter
Rewrites a SPARQL query to a single SQL query allowing theunderlying database to perform optimizations
Improved extensibility of Sparqlify's model of the underlying database:Custom SQL functions can now be programatically declared.
Web interface with syntax highlighting and live data generation foreasy mapping creation
Many bug �xes, new optimizations (SQL, LEFT JOIN, ORDER BY)
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 50 / 55
Achievements - LinkedGeoData
LinkedGeoData conversion simpli�ed to a set of SQL �les andSparqlify Mapping De�nitions
Monthy dumps now working and automatically scheduled
LinkedGeoData and Sparqlify are available as Debian Packages!1 2
1https://github.com/AKSW/Sparqlify2https://github.com/GeoKnow/LinkedGeoData
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 51 / 55
Achievements - TripleGeo
Converts shape�les /spatial DBMS output to RDF
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 52 / 55
Achievements - Linking
Orthodromic distance only supported by LIMES and SILK
Linking algorithm ORCHID for geospatial data
Reduces number of comparisons
For DBpedia (threshold in kilometres):
0.1 0.2 0.5 1
Threshold
104
105
106
107
Runti
me (
ms)
ORCHIDSILK
Linking papers at ESWC'13 (linking + cloud, best paper award) andISWC'13 (ORCHID algorithm)
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 53 / 55
Achievements - Facete
Generic faceted browser for HTTP SPARQL endpointsNested facets and client side pagination without pre-processingTested with up 10K spatial objects → Goal is to work withDBpedia/LGD
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 54 / 55
The End
Claus Stadlercstadler@informatik.uni-leipzig.deAKSW/Uni Leipzig
Jens Lehmannlehmann@informatik.uni-leipzig.deAKSW/Uni Leipzig
GeoKnow
http://geoknow.eu
Stadler, Lehmann (Univ. Leipzig) LinkedGeoData and GeoKnow 2013-09-19 55 / 55
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