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 Agenda Context and Aims Corpus Ontological Resources –AV Ontology, Medical Ontology Annotating the Videos Querying and Reasoning Performing SW-inspired Reasoning Conclusion

3. 2005/05/29 A. Isaac & R. Troncy - MSW'20052 Describe AV documents Various uses / Different granularities –Identification, feature extraction, structural decomposition, semantic description Description deep meaning cannot be accessed and processed by classical systems –Knowledge is often implicit: labels and comments in natural language –Formalisation for description syntax, not semantics Formal semantics should be interesting –Reasoning with AV document descriptions –Interoperability with formal domain-specific ontologies, allowing to mix AV and domain-related reasoning

4. 2005/05/29 A. Isaac & R. Troncy - MSW'20053 Objectives Settle an mini-experiment to show the benefits of using semantic web technologies for annotating audiovisual content Show that the use of: –formal ontologies, –annotation pattern, –inference capabilities … is highly desirable for a better access to AV content

5. 2005/05/29 A. Isaac & R. Troncy - MSW'20054 Corpus Medicine-related TV documentaries –30 documents, about 30 hours –50% deal with heart (surgery) theme Description point of view: how AV features are used to popularize scientific notions Describe both the form and the content –AV-oriented parts (documentary structure) –Theme-oriented parts (medicine notions)

6. 2005/05/29 A. Isaac & R. Troncy - MSW'20055 Ontological Resources Audio-Visual Core Ontology [Isaac & Troncy, 2004] –Characterization of programs and sequences (AV genre) –Decomposition of programs and sequences –Ability to introduce description from the point of view of the activities that constitute the context of AV documents roles of people involved, way production and broadcast are achieved, etc. Dual Legitimacy –Use: conceptualization grounded on observed purposes and domain initiatives, study of 30 years of documentary practices –Conception: 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 annotation –Documentary structure characterization –Segment content 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 Documentary patterns –Layered approach [Troncy, 2003] –AV description language [Troncy & Carrive, 2004] Knowledge-based Annotation Process –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

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 (annotation design pattern) –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 and Reasoning 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 Querying and Reasoning

16. 2005/05/29 A. Isaac & R. Troncy - MSW'200515 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

17. 2005/05/29 A. Isaac & R. Troncy - MSW'200516 Examples DL definitions (Composition) rule

18. 2005/05/29 A. Isaac & R. Troncy - MSW'200517 Summary Explicit triples Inferred triples All triples RDF Model129 AV Ontology52311081016041 Menelas Ontology 105342663737171 Instances27615071783 Total160413895454995

19. 2005/05/29 A. Isaac & R. Troncy - MSW'200518 Conclusion This experimentation: –Uses Semantic Web languages and tools for describing AV contents –Uses different ontologies to capture the structure and the content of the documents –Uses relational indexing pattern 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