1. 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

2. 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

3. 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

4. 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

5. 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)

6. 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]

7. 2005/05/29 A. Isaac & R. Troncy - MSW'20056 Ontological Resources

8. 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 )

9. 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

10. 2005/05/29 A. Isaac & R. Troncy - MSW'20059 Segmenting the Videos

11. 2005/05/29 A. Isaac & R. Troncy - MSW'200510 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]

12. 2005/05/29 A. Isaac & R. Troncy - MSW'200511 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

13. 2005/05/29 A. Isaac & R. Troncy - MSW'200512 Describing the Videos

14. 2005/05/29 A. Isaac & R. Troncy - MSW'200513 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

15. 2005/05/29 A. Isaac & R. Troncy - MSW'200514 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

16. 2005/05/29 A. Isaac & R. Troncy - MSW'200515 Examples DL definition Composition rule

17. 2005/05/29 A. Isaac & R. Troncy - MSW'200516 Summary Explicit triples Inferred triples All triples RDF Model129 AV Ontology52311081016041 Menelas Ontology 105342663737171 Instances27615071783 Total160413895454995

18. 2005/05/29 A. Isaac & R. Troncy - MSW'200517 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