<p>To encode, query and present the semantic content of digital video precisely and flexibly is very useful for many kinds of knowledge work: system analysis and evaluation, documentation and education, to name a few. However, that kind of video management is not a trivial matter. The traditional stratified annotation model has quite poor facilities for specifying the meaning – the structure and relationships – of the strata. Because of this, it may also be troublesome to present the annotations to the users in a clear and flexible manner.</p><p>This thesis presents <i>OntoLog</i>, a system for managing the semantic content of video. It extends the stratified annotation model by defining the <i>strata as objects and classes in ontologies</i>, thereby making their semantic meaning more explicit and relating them to each other in a semantic network. The same ontologies are also used to define properties and objects for describing both the strata, individual video intervals and entire videos. This constitutes a very customisable, expressive and precise description model, without sacrificing simplicity and conceptual integrity.</p><p>Arranging the annotation strata in a near-hierarchical network with specified semantics (classes, subclasses and instances) also enables reasoning about the annotations during query and browsing. In particular, it enables <i>visual aggregation of traditional timeline-based strata graphics</i>. Using this to create compact content visualisations, the OntoLog system is able to present tens of videos on screen at the same time, thus providing<i> inter-video browsing</i>. By judiciously disaggregating selected parts of the strata hierarchy, users can focus on relevant strata at their preferred level of detail – <i>overview-and-zoom</i> functionality for semantic annotations, in other words.</p><p>The OntoLog system has been implemented in the form of six Java applications and web services – together covering annotation editing, browsing, analysis, search, query and presentation with various approaches – built on top of an RDF database founded on SQL. The system has been tested under realistic conditions in several real-world projects, with good results. A novel information gathering interface for OntoLog data, Savanta, has been created. This is based on an iterative interaction paradigm featuring inter-video browsing, filtering, navigation and context-sensitive temporal analysis of the annotations. In a comparative usability evaluation, <i>Savanta</i> is shown to outperform more traditional user interfaces for video search/browsing with regard to expressive power, straightforwardness and user satisfaction.</p>
Identifer | oai:union.ndltd.org:UPSALLA/oai:DiVA.org:ntnu-707 |
Date | January 2005 |
Creators | Heggland, Jon |
Publisher | Norwegian University of Science and Technology, Faculty of Information Technology, Mathematics and Electrical Engineering, Fakultet for informasjonsteknologi, matematikk og elektroteknikk |
Source Sets | DiVA Archive at Upsalla University |
Language | English |
Detected Language | English |
Type | Doctoral thesis, monograph, text |
Relation | Doktoravhandlinger ved NTNU, 1503-8181 ; 2005:161 |
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