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

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

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 (Extended Version)

Magnus Knuth, Olaf Hartig, Harald Sack
CoRR, vol. abs/1608.08130 2016

Joint proceedings of the 2nd Workshop on Managing the Evolution and Preservation of the Data Web (MEPDaW 2016) and the 3rd Workshop on Linked Data Quality (LDQ 2016)

Jeremy Debattista, Javier D. Fernández, Magnus Knuth, Dimitris Kontokostas, Anisa Rula, Jürgen Umbrich, Amrapali Zaveri
number 1585 in CEUR Workshop Proceedings, 2016
Contributions to Proceedings:

Data Integration for the Media Value Chain

Henning Agt-Rickauer, Jörg Waitelonis, Tabea Tietz, Harald Sack
In Proceedings of the ISWC 2016 Posters & Demonstrations Track, of 1690, Kobe, Japan, 10 2016

Fine tuning CNNS with scarce training data - Adapting imagenet to art epoch classification

Christian Hentschel, Timur Pratama Wiradarma, Harald Sack
In Proc. Int. Conf. on Image Processing (ICIP 2016), pages 3693-3697, 9 2016 IEEE.

Quantitative Analysis of Art Market Using Ontologies, Named Entity Recognition and Machine Learning: A Case Study

Dominik Filipiak, Henning Agt-Rickauer, Christian Hentschel, Agata Filipowska, Harald Sack
In Proceedings of the 19th International Conference on Business Information Systems (BIS 2016), pages 79-90, Leipzig, Germany, 7 2016

I am a Machine, let me understand Web Media!

Magnus Knuth, Jörg Waitelonis, Harald Sack
In Web Engineering: 16th International Conference, ICWE 2016, Lugano, Switzerland, June 6-9, 2016. Proceedings, of LNCS, pages 467–475, 2016 Springer International Publishing.

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

Magnus Knuth, Olaf Hartig, Harald Sack
In Proc. of the 15th International Conference on Ontologies, DataBases, and Applications of Semantics (ODBASE 2016), 2016

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

Jörg Waitelonis, Henrik Jürges, Harald Sack
In Proc. of 12th Int. Conf. on Semantic Systems (SEMANTICS 2016), 2016

Evaluating Query and Storage Strategies for RDF Archives

Javier D. Fernández, Jürgen Umbrich, Axel Polleres, Magnus Knuth
In Proceedings of the 12th International Conference on Semantic Systems, pages 41–48, 2016 ACM.

DBpedia Links: The Hub of Links for the Web of Data

Milan Dojchinovski, Dimitris Kontokostas, Robert Rößling, Magnus Knuth, Sebastian Hellmann
In Proceedings of the SEMANTiCS 2016 Conference (SEMANTiCS 2016), 2016
 ...  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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