The emerge of Semantic Geoportals

1. The emerge of Semantic Geoportals Athanasis Nikolaos Konstantinos Kalabokidis Vaitis Michail Soulakellis Nikolaos

2. Agenda • Web portals and geo-portals • The Semantic Web • The emerge of semantic geo-portals • Related work • Summary & future work

3. The World Wide Web today • html • web browsers • hyperlinks

4. Web Portals personalized content (customization) Web Portal: A single point of access to information - a library of categorized and personalized content rich organization of information

5. Geo-portals interactive GIS mapping rich organization of spatial information rich organization of information Geo-portals:online access to collections of geospatial data

6. 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

7. Exploiting geo-data

8. The role of metadata in geoportals • Information providers publish metadata (descriptions about the data they want to share) • The (catalog) geo-portalorganizes the metadata in metadata records • Users search the metadata records and exploit data Or view metadata records

9. publishing metadata Submit metadata through GUI Metadata harvesting

10. Geospatial metadata standards • American Standard: • CSDGM(Content Standard for Digital GeospatialMetadata) • European Standard: • CEN/TC287 (EuropeanCommitteeforStandardization ) • EN ISO 19115:2005

11. Current implications • 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

12. The Semantic Web • rich semantic organization • ontologies (description schemata) • RDFS, OWL • resource descriptions • RDF • navigation based on conceptual relationships • semantic hyperlinks

13. …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

14. Metadata catalogs of a Semantic Geo- Portal in RDF String title belongsToTheme related content live data Documents Metadata record publisher Enumeration String serverURL ArcIMS service description Static documents String String on-line linkage Image service Feature service String spatial info downloadable content file size Enumeration Downloadable documents Map File String title “….” belongsToTheme related content publisher Natural Disasters “…” &r1 &r3 serverURL description belongsToTheme “…” downloadable content “…” on-line linkage Natural Disasters &r4 file size &r2 serverURL “…” spatial info “…” “…” “vector” r1: www.geoportal.com/services/r1 r2: www.geoportal.com/maps/r2 r3: www.geoportal.com/r3 r4: www.geoportal.com/download/r4

15. Requirements for semantic geo-portals • 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

16. 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

17. Our solution [cont] Examples: • Find all image services about natural disasters as well as related documents about them: • Find the descriptions of the Map Files that you can download: select X1,X2 from {X1;Image_Service}related_content{X2;Documents}, {X1;Image_Service}belongsToTheme{X3} where X3 = “Natural Disasters” select W from {;Map_Files}downloadable_content{X2;Downloadable_Documents}, {;Metadata_record}description{W}

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

19. Related work • geo-portals: • Geospatial-One-Stop • http://gos2.geodata.gov/ Semantic portals: ICS-FORTH Portal http://139.91.183.30:8999/RQLdemo

20. 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.

21. Future Work • Development of the appropriate geo-ontologies • Design of the geo-portal system

22. Thank you