Semantic Technologies

In recent years the Semantic Web has emerged as one of the most essential achievements for the future of the World Wide Web (WWW). Semantic Web technology extends the WWW but also enables to improve applications which are related to other fields such as communication, information, knowledge, media, and interaction technologies. Semantic Web provides not just new technologies and tools but also new paradigms and ways of thinking, to make information processing more efficient and more structured.

Our research is focussed on the devolpment and improvement of 'semantically supported multimedia retrieval and search technologies'.

Table of Contents

  • Current News
  • Prior Events and Activities
  • Research Topics
  • Research Team
  • Former Team Members
  • Teaching
  • Supervised Master Theses
  • Projects and Partners
  • In the Media
  • Recent Publications

Research Topics

  • (1) Semantic Multimedia
  • (2) Linked Data Engineering and Applications
  • (3) Semantically enhanced Information Retrieval (Semantic Search)
  • (4) Knowledge Mining and Ontological Engineering
  • (5) Semantically enriched e-Learning Applications

Job Offers

Research Team

Former Team Members

  • Dipl.-Inf. Katarina Birghan
  • Tamara Bobic, M.Sc.
  • Dipl.-Dokumentar Johannes Hercher
  • Dipl.-Inf. Zalan Kramer
  • Johannes Osterhoff, M.A.
  • Bernhard Quehl, M.Sc.
  • Dr. Nadine Steinmetz
  • Dipl.-Inf. Lina Wolf
  • Dipl.-Ing. Haojin Yang
  • Joscha Jäger, M.A. (internship)

Our group

Left to Right: Nadine Steinmetz, Johannes Osterhoff, Dr. Harald Sack, Jörg Waitelonis, Christian Hentschel, Bernhard Quehl


 ...  2012  2013  2014  2015  2016     Advanced Search

Scheduling Refresh Queries for Keeping Results from a SPARQL Endpoint Up-to-Date

Magnus Knuth Olaf Hartig Harald Sack

Don't compare Apples to Oranges - Extending GERBIL for a fine grained NEL evaluation

Jörg Waitelonis Henrik Jürges Harald Sack
Contributions to Proceedings:

I am a Machine, let me understand Web Media!

Magnus Knuth, Jörg Waitelonis, Harald Sack
In Proceedings of International Conference on Web Engineering (ICWE2016), of LNCS, 2016 Springer.
 ...  2012  2013  2014  2015  2016 

Projects and Partners


  • AV-Portal Gottfried-Leibnitz-Universität Hannover, project with Technische Informationsbibliothek Hannover (TIB)
  • Semantic Media Explorer (SEMEX)
    The Semantic Media Explorer is a demonstrator that combines the latest media analysis processes to provides optimal access to video content.
  • MEDIAGLOBE Project
    The aim of MEDIAGLOBE is to open and interlink heterogenouse and currently isolated information sources in media archives and broadcasting corporation. Project partners: DEFA-spektrum, Medienbildungsgesellschaft Babelsberg mbH, Blue Order GmbH
    The purpose of CONTENTUS is to develop basic technologies with which to access, archive and search for multi-media cultural assets and works of art.
    Yovisto is a video search engine specialized in academic content. Yovisto's search index is based on the combination of automated content based video analysis with user generated collaborative annotation (collaborative tagging, discussions, and comments). In difference to traditional video search engines, Yovisto enables pinpoint access within video data by providing fine-granular, time-dependent metadata.
  • Semantic Games
    Games with a purpose that are dedicated to create and curate semantic content.

Current News

Prior Events and Activities









2014 (SS)

2013/14 (WS)

2013 (SS)

  • Seminar (Master): Semantic Multimedia (Blog)
  • Seminar (Bachelor): Multimedia Analyse Technologien (Blog)
  • Schülerkolleg (für Schüler der 8. bis 10. Klasse): Internetsuche und Google PageRank - Wie wird was durch wen gefunden?

    • Woche 1 - 09.04.2013: Die Geschichte der Web-Suchmaschinen (pdf)
    • Woche 2 - 23.04.2013: Term- und Dokumentenranking (pdf)
    • Woche 3 - 07.05.2013: Google Page Rank (pdf)
    • Woche 4 - 21.05.2013: Personalisierung und Web Crawling (pdf)
    • Woche 5 - 04.06.2013: Semantische Suche



2012/13 (WS)

2012 (SS)

2011/12 (WS)

2011 (SS)

2010/11 (WS)

2010 (SS)

2009/10 (WS)




Supervised Master Theses

  • Gerald Töpper: Erweiterung der DBpedia Ontologie und des Extraction Frameworks zur Sicherung der Datenqualität. (finished April 2012)
  • Peter Retzlaff: Visualisierung von Bag-of-Visual-Words-Vektoren für die Visual Concept Detection (finished March 2014)
  • Sebastian Stange: Evaluierung einer semantischen Videosuche und Ermittlung geeigneter Videoanalysetechniken (finished March 2014)
  • Michael Wolowyk: Semantic Recommender Systems (preliminary title) (in progress)

Open Master Theses

Please find a list of possible topics for Master Theses. Contact us, if you are interested in one of these topics or have own suggestions.

  • Video Analysis:

    • OCR Spellcorrection
    • Tag Relevance Estimation in Photo Communities
    • Learning Local Image Descriptors

  • Linked Data and Semantic Web:

    • Named Entity Evolution
    • Authority File Mapping
    • A Mereology for Media Fragments






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