INSPIRE Conference Automatic metadata generation for the Web geo-resources

Transcription

1 INSPIRE Conference 2011 Automatic metadata generation for the Web geo-resources B. Borjas, A.J. Florczyk, F.J. López-Pellicer, J. Nogueras-Iso, F.J. Zarazaga-Soria June 28, Edinburgh Advanced Information Systems Laboratory (IAAA)

2 Agenda Geospatial Web Resources Web Community vs. Spatial Community Spatial Community interest in GWRs Metadata of Web Resources for Spatial Community Web Pages Metadata Automatic Metadata Generation AMG Architecture Prototype Implementation Experiment Results Conclusions and Future Work

3 Geospatial Web Resources Web Community Spatial Community Web Resources Geoportals Geo-contextualization of Web resources Web 2.0 flavour Collaboration Participation Content creation communities, Geotagging

4 Geospatial Web Resources Spatial Community Geospatial Information - Core Web as technological support Collaboration for multidisciplinary science Incremental Geospatial Cyberinfrastructure (GCI)

5 Geospatial Web Resources Spatial Community Interest Expert products out of any GCI Common Web User Participation: Valuable Collaborator How to incorporate?? Metadata! Discovery Spatial Community: Digital Library paradigm Web Community: Search Engines, DL

6 The Web & Metadata Problems Search Engine Rules! Web content publishers do not pay attention to ensure appropriate description of the resources or deliberately distort it. Since metadata contained within the HTML pages are used be the agents for indexing, the content publishers use this metadata in order to gain visibility within search engines. Therefore, this metadata may not be reliable.

7 Metadata of Web Resources for Geospatial Community What model? A minimal model allowing incorporation into a GCI (to fill a CSW record) How to create? Analysis of content Analysis of context (neighbourhood within the Web graph) Which Web Resource? Any format and encoding Geotagged Web 2.0 products (images, videos,...) OWS instances and content (e.g. WMS responses) Web Pages...

8 Metadata of Web Resources for Spatial Community What model? A minimal model allowing incorporation into a GCI (to fill a CSW record) How to create? Analysis of content Analysis of context (neighbourhood within the Web graph) Which Web Resource? Any format and encoding Geotagged Web 2.0 products (images, videos,...) OWS instances and content (e.g. WMS responses) Web Pages Geoportals - the access points to GCIs Context information of Geospatial Web Resources...

9 Web Page Metadata HTML

10 Geo-Metadata in HTML

11 Conceptual Mapping

12 Conceptual Mapping

13 Automatic Metadata Generation Functionality Overview

14 Automatic Metadata Generator Architecture

15 Automatic Metadata Generation Main Components In/Out Manager The Generator Autodetector Generator Extractor Manager Extractor

16 Automatic Metadata Generation Architecture: In/Out Manager In/Out Manager Takes as input an XML document which model follows one of the supported schema. Creates of the output document

17 Automatic Metadata Generation Architecture: Generator Autodetector Generator Autodetector Analyzes the input document and selects appropriate generator component (Generator) according to its schema.

18 Automatic Metadata Generation Architecture: Generator Generator Knows how to work with this schema, and it operates on an internal resource description model Extracts the resource URL from the input document and delegates the extraction of metadata sets.

19 Automatic Metadata Generation Architecture: Extractor Manager Extractor Manager According to the requested metadata set (MD Set) and Web resource type, invokes appropriate Extractor

20 Automatic Metadata Generation Architecture: Extractor Extractor Retrieves content of the Web resource (Connector), and returns the requested metadata set. Extractors may use different strategy for extracting the same metadata set (Parser)

21 Automatic Metadata Generation Prototype Implementation The system has been implemented in Java using the Apache Tika project source as a starting point. The implemented prototype is dedicated for extraction of basic metadata that are necessary to describe a geospatial resource for further deployment in a OGC catalogue service. The generated metadata consist of core returnable properties supported by a OGC CSW

22 Automatic Metadata Generation Experiments Test Dataset Geoportal Web pages from the Spanish SDIs of regional level Experiment Nº 1: Automatic extraction of the metadata (<title> + <meta> elements) Experiment Nº 2: A new generator has been provided to make use of several additional extractors: To extract links and its descriptions To extract common words from text To extract common phrases To identify place names (NLP + Georeferencing)

23 Automatic Metadata Generation Experiment Results: Metadata Example <dc:creator>agencia del Conocimiento y la Tecnologia</dc:creator> <dc:publisher>gobierno de La Rioja</dc:publisher> <dc:subject>iderioja, Gobierno de La Rioja, Cartografia, Rioja, IDE, Infraestructura Datos Espaciales, Mapas, Visor, Geografia, Territorio, Ortofoto, CAD, Metadatos, Saicar</dc:subject> <dct:abstract>infraestructura de Datos Espaciales de La Rioja.</dct:abstract> <dc:identifier>002321</dc:identifier> <dc:relation>offeredby</dc:relation> <dc:source> <dc:type>html Web Page</dc:type> <dc:title>infraestructura de Datos Espaciales - Gobierno de La Rioja - IDERIOJA</dc:title> <dct:modified> </dct:modified>

24 Automatic Metadata Generation Experiment Results Experiment Nº 1: The main problem was the extraction of geographic metadata (coverage) because the processed pages do not contain the geographic metadata elements. Experiment Nº 2: The coverage element has been completed in most cases, and the manual review confirmed that its correctness in 67%. On the other hand, for some pages, the system could not generate metadata. The manual review indicated that the developed prototype can not deal with the script languages that generate content (JavaScript).

25 Conclusions & Future Work The Web pages often contain no geographic metadata which is the main problem for the extraction of geographic extent information (coverage). It was necessary to extend the system with NPL algorithms to extract place names, and use a georeferencing component to translate the name places into an appropriate geographic extent. The work in the future will focus on other Web georesources, such as OGC service description documents (GetCapabilities response of OWS service), Shapefiles, KML and GeoRSS files. The approaches to improve the generation of metadata for the Web pages that use scripts will be investigated. The multilingual support will be considered.

26 Francisco J. Lopez-Pellicer Advanced Information Systems Laboratory (IAAA) IAAA is currently a partner in the EuroGeoSource project