Using Several Ontologies for Describing Audio-Visual Documents: A Case Study in the Medical Domain Sunday 29 th of May, 2005 Antoine Isaac 1 & Raphaël Troncy 2 Multimedia and the Semantic Web

2005/05/29 A. Isaac & R. Troncy - MSW'20051 Describe AV documents Various uses / Different granularities –Identification, feature extraction, structural decomposition, semantic description Description deep meaning cannot be accessed and processed by systems –Knowledge is often implicit: labels and comments in natural language Formal semantics should be interesting –Reasoning with AV document descriptions –Interoperability with formal domain-specific ontologies, allowing to mix AV and domain-related reasoning  Use of Semantic Web technologies to better retrieve, re-use and process AV content

2005/05/29 A. Isaac & R. Troncy - MSW'20052 Objectives Settle an mini-experiment to show the benefits of using semantic web technologies for annotating multimedia content Show that the use of: –formal ontologies and rules, –inference capabilities, –annotation design pattern … are highly desirable for better accessing AV content

2005/05/29 A. Isaac & R. Troncy - MSW'20053 Agenda Corpus Ontological Resources –AV Ontology –Medical Ontology Annotating the Videos Querying the Knowledge Base Performing Reasoning Conclusion

2005/05/29 A. Isaac & R. Troncy - MSW'20054 Corpus Medicine-related TV documentaries –30 documents, about 30 hours –50% deals with heart and heart surgery theme Good examples of how AV features are used to popularize scientific notions Describe both the form and the content –AV-oriented parts (documentary structure) –Thematic-oriented parts (medicine notions)

2005/05/29 A. Isaac & R. Troncy - MSW'20055 Ontological Resources Building an Audio-Visual Core Ontology [Isaac & Troncy, 2004] –Characterization of programs and sequences (AV genre) –Decomposition of programs and sequences –Ability to introduce description of the activities that constitute the context of AV documents (roles of people involved, way production and broadcast are achieved, etc.) Legitimacy –Grounding conceptualization by observed purposes and domain initiatives, study of 30 years of documentary practices –Articulation with an upper-level ontology: DOLCE [Gangemi, 2002]

2005/05/29 A. Isaac & R. Troncy - MSW'20056 Ontological Resources

2005/05/29 A. Isaac & R. Troncy - MSW'20057 Ontological Resources Extension of AV core with specific application notions –Exemplification, demonstration, etc. Re-use of Medical Ontologies –Menelas: domain of coronary pathologies Concepts dealing with heart surgery –Alternative choices are possible Galen (concepts dealing with surgical procedures) Articulation between the ontologies –No use of automatic alignment methods or tools –State by hand OWL axioms ( equivalentClass )

2005/05/29 A. Isaac & R. Troncy - MSW'20058 Description Process Segmentation of the AV material –Selection of relevant documentary items Knowledge-based AV description –Documentary structure characterization –Segment description

2005/05/29 A. Isaac & R. Troncy - MSW'20059 Segmenting the Videos

2005/05/29 A. Isaac & R. Troncy - MSW' Describing the Videos Annotation Mechanism –The structure is described at the knowledge level Concepts and relations from the AV ontology are manually introduced in the description –Content description Link to external world themes and entities Documentary patterns –Layered approach [Troncy, 2003] –AV description language [Troncy & Carrive, 2004]

2005/05/29 A. Isaac & R. Troncy - MSW' Describing the Videos Relational Indexing Pattern –Help for user: specify how concepts and relations have to be used –Important for ontology conception and use (with reasoning knowledge) Simple pattern that can lead to complex descriptions –Recursive relational structure

2005/05/29 A. Isaac & R. Troncy - MSW' Describing the Videos

2005/05/29 A. Isaac & R. Troncy - MSW' Querying the Knowledge Base Example: « retrieve the programs that explain a disease and show one of its causes » Need for the following inferences: –Subsumption –Composition

2005/05/29 A. Isaac & R. Troncy - MSW' Performing reasoning A layered complexity approach –RDFS: subsumption –OWL DL: complex definitions + algebraic properties –Rules: horn clauses Concrete implementation –RDFS: Sesame Architecture [Broekstra, 2002] –OWL DL: BOR Reasoner [Simov, 2002] –OWL-DLP [Grosof, 2003] + Rules : Sesame custom inference module

2005/05/29 A. Isaac & R. Troncy - MSW' Examples DL definition Composition rule

2005/05/29 A. Isaac & R. Troncy - MSW' Summary Explicit triples Inferred triples All triples RDF Model129 AV Ontology Menelas Ontology Instances Total

2005/05/29 A. Isaac & R. Troncy - MSW' Conclusion This experimentation: –Uses Semantic Web languages and tools for describing AV contents –Uses several ontologies to capture both the structure and the content of the documents –Uses relational indexing patterns for the annotation Future work: thorough evaluation of those techniques involving real users A problem that cannot be generally solved: fixing a trade-off between expressivity and tractable computation –Ad hoc, according to the needs of the application targeted