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-portal organizes 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 Geospatial
  Metadata)
• European Standard
• CEN/TC287 (European Committee for Standardization
  )
• EN ISO 191152005

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
Feature service
Image service
String
spatial info
downloadable content
file size
Downloadable documents
Map File
Enumeration
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 X1Image_Servicerelated_conte
ntX2Documents, X1Image_ServicebelongsToTheme
X3 where X3 Natural Disasters

select W from Map_Filesdownloadable_contentX2
Downloadable_Documents, Metadata_recorddescr
iptionW
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.geod
ata.gov/
Semantic portals ICS-FORTH Portal
http//139.91.183.308999/RQLdemo
20
Summary

• Portals, geo-portals, metadata catalogs
• The current organization in geo-portals 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 users navigation paths.

21
Future Work

• Development of the appropriate geo-ontologies
• Design of the geo-portal system

22
Thank you