
Recently we have seen a large increase in the amount of geospacial data that is being published using RDF and Linked Data principles. Efforts such as the W3C Geo XG, and most recently the GeoSPARQL initiative are providing the necessary vocabularies to publish this kind of information on the Web of Data. map4rdf is a mapping and faceted browsing tool for exploring and visualizing RDF datasets enhanced with geometrical Information.
map4rdf is an open source software. Just configure it to use your SPARQL endpoint and provide your users with a nice map-based visualization of your data. The geospatial aspects of the data can be modelled using either the data model from W3C Geo XG or the geometrical data model proposed by GeoLinkedData
map4rdf provides:
Once you have installed map4rdf, you can see the initial display
Click on the plus sign on the right side of the map.
The application will show the available layers you have. Select one of them.
Select a particular facet
The application will show only the resources of the facet selected
This is a new feature of map4rdf. It allows us to filter the resources to visualize.
Click on the pencil icon to turn on the drawing mode.
Select the area of the map you want to see resources
If you want to remove the filter click on remove filter button.
Finally click on the pencil icon to turn off the drawing mode.
You can suggest editions of a given resource. For example, let us assume that the resource that represents the Murcia Airport has not the correct information.
First, you have to click on the resource, and a dialog will appear.
Next, you have to click on "To Edit, click here". Then, you will see the edition page that shows the resource and its properties. You can collapse the properties and suggest changes for the properties/values. When you finish you can click on "save button", and the modifications will store in a file on the server file system.
The general configuration parameters of map4rdf are defined within the configuration.properties file. The configuration of the faceted browser is defined by the facets.ttl file.
This file is located within map4rdf's webapp directory, at /WEB-INF/configuration.properties
endpoint.url=http://dbpedia.org/sparql geometry.model=DBPEDIA ui.google_maps_api_key=ABQIAAAAzLYqFkZVLHv0seO36vhZahTVXfBc-erLsJZtZLx-fZLjxiIMWBTUgr5s9aY_jQ5Fyqku0qQKuoGE8A facets.automactic=true edit_depth=3 rdf_store_path=/home/user/code/tmp/rdf/
This file is writen in turtle syntaxt and it is located within map4rdf's webapp directory, at /WEB-INF/facets.ttl
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> . @prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> . @prefix xsd: <http://www.w3.org/2001/XMLSchema#> . @prefix foaf: <http://xmlns.com/foaf/0.1/> . @prefix map4rdf: <http://code.google.com/p/map4rdf/wiki/ontology#> . _:rdfTypeFacet a map4rdf:FacetGroup; map4rdf:facetPredicate rdf:type; rdfs:label "Type"@en; rdfs:label "Tipo"@es; .
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> . @prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> . @prefix xsd: <http://www.w3.org/2001/XMLSchema#> . @prefix foaf: <http://xmlns.com/foaf/0.1/> . @prefix map4rdf: <http://code.google.com/p/map4rdf/wiki/ontology#> . _:rdfTypeFacet a map4rdf:FacetGroup; map4rdf:facetPredicate rdf:type; rdfs:label "Type"@en; rdfs:label "Tipo"@es; map4rdf:facet <http://dbpedia.org/ontology/Person>; map4rdf:facet <http://dbpedia.org/ontology/University>; . <http://dbpedia.org/ontology/Person> rdfs:label "Person"@en; rdfs:label "Persona"@es; . <http://dbpedia.org/ontology/University> rdfs:label "University"@en; rdfs:label "Universidad"@es; .