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MPEG-7 Interoperability Use Case

MPEG-7 Interoperability Use Case. Motivation. MPEG-7: set of standardized tools for describing multimedia content at different abstraction levels Implemented in the form of XML Schemas Lack of explicit semantics: intended semantics in form of documentation

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MPEG-7 Interoperability Use Case

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  1. MPEG-7 Interoperability Use Case

  2. Motivation • MPEG-7: set of standardized tools for describing multimedia content at different abstraction levels • Implemented in the form of XML Schemas • Lack of explicit semantics: intended semantics in form of documentation • Lack of precise semantics: ambiguities resulting from flexibility in structuring the descriptions

  3. Motivation (cont’d) • Attach formal semantics to mpeg7 by translating it to an ontology • The lack of precise and explicit semantics leaves room for different interpretations  interoperability issues raised among the developed mpeg7 ontologies

  4. Examples I • Semantically identically metadata can be represented in multiple ways • E.g. annotating an image depicting ‘Zidane scoring against England’ • Possible ways: using free annotation, keywords, structured annotations etc.

  5. Examples I (cont’d) <StructuredAnnotation> <Who> <Name xml:lang="en">Zinedine Zidane</Name> </Who> <WhatAction> <Name xml:lang="en"> Zinedine Zidane scoring against England. </Name> </WhatAction> </StructuredAnnotation> <FreeTextAnnotation xml:lang="en"> Zinedine Zidane scoring against England </FreeTextAnnotation> <KeywordAnnotation xml:lang="en"> <Keyword>Zinedine</Keyword> <Keyword>Zidan</Keyword> <Keyword>scoring</Keyword> <Keyword>England</Keyword> <Keyword>goal</Keyword> </KeywordAnnotation>

  6. Example II • The image representation in itself as a multimedia entity can be performed in multiple ways as well • Possible ways: using the Stillregion DS or even the VideoSegment DS: no formal semantics to prevent one from selecting to interpret an image as a still region or as a frame of a video sequence

  7. Example III • Semantically different metadata can be represented using the same description tool • E.g., the Multimedia Description Schemes:VideoSegment DS can be used to represent a single frame in a video, an arbitrary sequence of frames, or the full video sequence • Three different semantic concepts: frame, shot, video that can’t be discriminated based on the provided XML Schemas

  8. Example IV • Loose (intended) semantics of MPEG-7 e.g. with respect to the intended meaning of the structure decomposition schemes • E.g., not part-whole semantics: having an image annotated as ‘Zidane scoring’ and a second image, having a segment annotated the same, a single query wouldn’t be adequate to retrieve both

  9. Approaches to building an MPEG-7 ontology • The Hunter approach • Initially a DAML+OIL enriched RDFS ontology, subsequently translated into OWL • Intended to be used under a core ontology (ABC) to enable harmonization with domain ontologies • Decomposition captured using subclass constructs • However no axioms included (e.g. an image consists of a set of spatial, and not temporal, segments)

  10. Approaches to building an MPEG-7 ontology (cont’d) • The SMART Web project approach • The MultimediaContent and Segment classes along with corresponding properties implement the recursive nature of multimedia content decomposition • Partial axioms

  11. Approaches to building an MPEG-7 ontology (cont’d) • Tsinaraki’s approach • Translate the MPEG-7 MDS into OWL to serve as a core ontology for the integration of domain specific knowledge into the MPEG-7 semantic metadata • Domain ontologies need to be ‘mapped’ to the MPEG-7 schemas

  12. The Hunter’s and Tsinaraki’s approaches in practice • Use Case: Annotate and image of Zidane scoring :image01 mpeg7:depicts :goal01 :goal01 abc:hasAction :scoring01 :scoring01 abc:hasAgent s:_b1 s:_b1 :hasName :“Zinedine Zidane” :image01 rdf:type mpeg7:Image :goal01 rdf:type s:Goal :scoring01 rdf:type s:Scoring mpeg7:Image rdfs:subclass mpeg7:MultimediaContent mpeg7:MultimediaContent rdfs:subclass abc:Manifestation s:Scoring rdfs:subclass abc:Action s:Goal rdfs:subclass abc:Event :region01 rdf:type mpeg7:StillRegion (Hunter’s approach)

  13. (cont’d) :Zidane rdf:type mpeg7:PlayerObject mpeg7:PlayerObject owl:subclass mpeg7:AgentObjectType mpeg7: AgentObjectType rdfs:subclass mpeg7:SemanticType :Zgoal rdf:type s:Goal s:Goal rdf:type mpeg7:EventType mpeg7: EventType rdfs:subclass mpeg7:SemanticType :Zidane mpeg7:Relation :Zgoal (Tsinaraki’s approach)

  14. Possible solutions • Define semantic mappings between the various mpeg7 ontologies (exploit the potential of using rules on top of ontologies and reason on them) • Built a core multimedia ontology (exploit perhaps a foundational ontology’s axiomatization to ensure not only explicit but precise semantics as well) • Use of ‘semantically enabled’ profiles (again formal ways to specify the semantics constraints are required)

  15. Thank you!

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