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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


 ...  2010  2011  2012  2013  2014  ...     Advanced Search

A framework for improved video text detection and recognition

Haojin YANG Bernhard Quehl Harald Sack
Multimedia Tools and Applications, vol. 69(1):217-245 2012

Towards exploratory video search using linked data

Jörg Waitelonis Harald Sack
Multimedia Tools and Applications, vol. 59(2):645 - 672 2012
Beiträge in Tagungsbänden:

Evaluating Entity Summarization Using a Game-Based Ground Truth

Andreas Thalhammer, Magnus Knuth, Harald Sack
In Proceedings of 11th International Semantic Web Conference (ISWC 2012), Boston, MA, USA, 11 2012 Springer.

Cross-Dataset Learning of Visual Concepts In: Adaptive Multimedia Retrieval: User, Context, and Feedback

Chirstian Hentschel, Harald Sack, Nadine Steinmetz
In Proceedings of the 10th International Workshop on Adaptive Multimedia Retrieval (AMR 2012), 10 2012 to be published

DBpedia Ontology Enrichment for Inconsistency Detection

Gerald Töpper, Magnus Knuth, Harald Sack
In Proceedings of the 8th International Conference on Semantic Systems (I-SEMANTICS 2012), Graz, Austria, 9 2012 ACM.

Open Up Cultural Heritage in Video Archives with Mediaglobe

Christian Hentschel, Johannes Hercher, Magnus Knuth, Johannes Osterhoff, Bernhard Quehl, Harald Sack, Nadine Steinmetz, Jörg Waitelonis, Haojin Yang
In Proceedings of the 12th International Conference on Innovative Internet Community Services (I2CS 2012), of Lecture Notes in Informatics, 6 2012

A Skeleton based Binarization Approach for Video Text Recognition

Haojin Yang, Bernhard Quehl, Harald Sack
In Proceedings of the 13th International Workshop on Image analysis for multimedia interactive services (WIAMIS 2012), 5 2012

Collaboratively Patching Linked Data

Magnus Knuth, Johannes Hercher, Harald Sack
In Proceedings of 2nd International Workshop on Usage Analysis and the Web of Data (USEWOD), pages 33-40, Lyon, France, 4 2012 ACM.

Text Detection in Video Images Using Adaptive Edge Detection and Stroke Width Verification

Haojin Yang, Bernhard Quehl and Harald Sack
In Proceedings of the 19th Int. Conf. on Systems, Signals and Image Processing (IWSSIP 2012), 4 2012
 ...  2010  2011  2012  2013  2014  ... 

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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