University of the Aegean Department of Geography The

University of the Aegean, Department of Geography The emerge of Semantic Geoportals Athanasis Nikolaos Konstantinos Kalabokidis Vaitis Michail Soulakellis Nikolaos

University of the Aegean, Department of Geography Agenda • • • Web portals and geo-portals The Semantic Web The emerge of semantic geo-portals Related work Summary & future work

The World Wide Web today University of the Aegean, Department of Geography • html • web browsers • hyperlinks

Web Portals University of the Aegean, Department of Geography personalized content (customization) rich organization of information Web Portal: A single point of access to information - a library of categorized and personalized content

Geo-portals University of the Aegean, Department of Geography interactive GIS mapping richorganization rich of information of spatial information Geo-portals: online access to collections of geospatial data

University of the Aegean, Department of Geography How geo-portals work • Information providers: publishing GIS data and services • Geo-portal: provides the rich organization of GIS data through its GUI • GIS user community: searches the portal and exploits data of interest

University of the Aegean, Department of Geography Exploiting geo-data

University of the Aegean, Department of Geography The role of metadata in geoportals • Information providers publish metadata (descriptions about the data they want to share) • The (catalog) geo-portal organizes the metadata in metadata records • Users search the metadata records and exploit data Or view metadata records

publishing metadata University of the Aegean, Department of Geography Submit metadata through GUI Metadata harvesting

Geospatial metadata standards • American Standard: University of the Aegean, Department of Geography – CSDGM (Content Standard for Digital Geospatial Metadata) Metadata = Identification_Information + {Data_Quality_Information} + {Spatial_Data_Organization_Information} + {Spatial_Reference_Information} + {Entity_and_Attribute_Information} + {Distribution_Information} • European Standard: – CEN/TC 287 (European Committee for Standardization ) • EN ISO 19115: 2005

Current implications University of the Aegean, Department of Geography • Lack of a uniform framework for describing geographic metadata – Deficiency to integrate / publishing metadata in geo-portals • Current standards are unable to capture the data semantics they describe • Semantic heterogeneity – Semantic conflicts in modeling - terminology (i. e. homonyms, synonyms) – Insufficiency of XML (GML) to solve semantic discrepancies

The Semantic Web • rich semantic organization University of the Aegean, Department of Geography – ontologies (description schemata) • RDFS, OWL – resource descriptions • RDF • navigation based on conceptual relationships – semantic hyperlinks

University of the Aegean, Department of Geography …and the geospatial Semantic Web • Development of spatial ontologies and with a formal semantics • Classification of geo-data under the appropriate classes of the ontologies • Processing of geospatial queries against these semantic ontologies

Metadata catalogs of a Semantic Geo- Portal in RDF Enumeration String belongs. To. Theme server. URL live data Metadata record Documents Arc. IMS service Image service University of the Aegean, Department of Geography title related content spatial info downloadable content Downloadable file size documents title related content Natural Disasters server. URL&r 1 “…” server. URL&r 2 &r 3 downloadable content “…” r 1: www. geoportal. com/services/r 1 String Enumeration “…. ” publisher belongs. To. Theme Natural Disasters String on-line. String linkage Feature service belongs. To. Theme publisher description Static documents Map File String r 2: www. geoportal. com/maps/r 2 &r 4 file size “…” r 3: www. geoportal. com/r 3 “…” description on-line linkage “…” spatial info “vector” r 4: www. geoportal. com/download/r 4

Requirements for semantic geo-portals University of the Aegean, Department of Geography • Semantic navigation through – hierarchies of classes/properties – concept relationships – resources relationships • semantic querying – data/schema querying – filtering conditions • representation of geo-data – Mapping – Live data maps (Web Map Service- WMS) • Publishing/representation of metadata according to spatial ontologies

University of the Aegean, Department of Geography Our solution • expresses the semantic meaning of the geospatial resources using RDFS ontologies and RDF resource descriptions • exploits a declarative query language (RQL) to resource descriptions – filtering – on demand construction of RQL queries • according to user navigation in the schema/data

Our solution [cont] Examples: University of the Aegean, Department of Geography • Find all image services about natural disasters as well as related documents about them: select X 1, X 2 from {X 1; Image_Service}related_content{X 2; Documents}, {X 1; Image_Service}belongs. To. Theme{X 3} where X 3 = “Natural Disasters” • Find the descriptions of the Map Files that you can download: select W from {; Map_Files}downloadable_content{X 2; Downloadable_Documents}, {; Metadata_record}description{W}

Our solution [cont] University of the Aegean, Department of Geography – Uses open source map tools • • • Map. Tools (image server) WMS (GIS services) php + apache (web server) – Provides customization capabilities through the portlet framework of Jetspeed portlets: pluggable, reusable components of portal

Related work University of the Aegean, Department of Geography geo-portals: Geospatial-One-Stop http: //gos 2. geodata. gov/ Semantic portals: ICS-FORTH Portal http: //139. 91. 183. 30: 8999/RQL demo

University of the Aegean, Department of Geography Summary • Portals, geo-portals, metadata catalogs • The current organization in geo-portal’s metadata catalogs is unable to capture the semantics of the data being described • Semantic geo-portals: • organize their resources according to geospatial ontologies • exploit semantic query languages (RQL) to provide access to information resources corresponding to the user’s navigation paths.

University of the Aegean, Department of Geography Future Work • Development of the appropriate geoontologies • Design of the geo-portal system

University of the Aegean, Department of Geography Thank you