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Exposing Semantics to Drive Transcoding
 

Exposing Semantics to Drive Transcoding

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The World Wide Web (Web) is a visually complex, dynamic, multimedia system that can be inaccessible to people with visual impairments. SADIe uses semantic annotations of a Website's Cascading Style ...

The World Wide Web (Web) is a visually complex, dynamic, multimedia system that can be inaccessible to people with visual impairments. SADIe uses semantic annotations of a Website's Cascading Style Sheet (CSS) to drive a transformation process that can improve access to content for visually impaired users. The original process of annotating the CSS involved the use of an upper ontology, extended by a site specific lower ontology. While this approach provided rich annotation of the CSS terms, experience suggests that components within the model were inappropriate for the interactive system we were developing. This experience has led to a more pragmatic approach that still provides the necessary semantics required to drive the SADIe transcoding tool, but in a more lightweight manner. This paper describes the lessons learnt from building the ontological models for the SADIe platform, highlighting pitfalls that developers of ontologies in interactive systems should be wary of.

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    Exposing Semantics to Drive Transcoding Exposing Semantics to Drive Transcoding Presentation Transcript

    • Exposing Semantics To Drive Transcoding
      Darren Lunn, Sean Bechhofer and Simon Harper
    • 2/28
      Summary
      Visual Rendering Can Provide Semantic Information
      Semantics Can Be Used to Drive a Transformation Process
      Poor Design Decisions Can Hinder Flexibility and Adoption
      A Well Defined Model and a Little Pragmatism Goes a Long Way
    • 3/28
      The Web
      Focuses on Presenting Information in a Visual Manner
      Images
      Columns
      Chunks
      Some Knowledge is only Available Implicitly from the Page Rendering
    • 4/28
      Implicit Knowledge
      Advertisement
      Banner
      Menu
      Main Content
    • 5/28
      Assistive Technology
      Visually Impaired Users use Assistive technologies e.g. Screen Readers
      Render Pages Sequentially in Audio
      Achieved by Accessing the Underlying HTML
      Focus on Visual Presentation Rather than Content Hampers This
      Particularly if Attention is Not Paid to Coherent Design
      Subtleties of Visual Presentation Can be Lost
    • 6/28
      Accessing CNN In Audio
    • 7/28
      Screen Readers
      Traversal of Content is Serial
      Top-to-bottom
      Left-to-Right
      Important Information may not be Encountered Until Later On.
      Information Such as Menus may be Repeated for Every Page
      Tiresome if the User has to Wait for the Menu for Each Page
    • 8/28
      SADIe Approach
      Main Story
      Heading
      Banner
      Menu
      Banner
      Story Overview
      Headline
      Story Overview
      Main Story
      Tabs
      Advertisement
      Image
    • 9/28
      Original Annotation Solution
      Use an Ontology as an Abstraction to represent Basic Concepts Appearing in the Page
      Annotate the CSS Rather than the Page
    • 10/28
      Proposed Solution
      Ontology
      Transformed
      Page
      HTML
      Rendered
      Page
      CSS
    • 11/28
      Two-Part Ontology
      An Upper Ontology Provides Basic Information about Authoring Concepts
      This is Extended to Provide information about Particular Style Sheets
      The Definitions in these Ontologies Provide the Annotation of the CSS Elements
    • 12/28
      Architecture
      Application
      Upper Ontology
      Site-Specific Extension
      HTML
      CSS
    • 13/28
      Overarching Aim
      Describe Semantic Structure of Websites
      Use Inference Engines to Determine Relationships Between Elements of the Website
      Transcode Website Based on these Relationships
    • 14/28
      Success?
      Transcoding was Successful on a Diverse Range of CSS-based Sites
      User Studies Demonstrated the Usefulness of the Transformations
      But the Model had Weakness that Limited The Approach
    • 15/28
      Application Functionality vs. Semantic Structure
      SADIe
      Removable
      NonRemovable
      Menu
      Priority
      Low
      Medium
      High
    • 16/28
      Application Functionality vs. Semantic Structure
      Menu
      High Priority
      Removable
    • 17/28
      Separate Functionality From Domain Knowledge
      We Advocate Separation of Structure (HTML) from Presentation (CSS)
      Also Separate Knowledge from Application Functionality
      Split Ontology Into Two
      Push More Computation into the Application
    • 18/28
      Why Separate
      Adds Flexibility to the Overall Application
      Adds Flexibility to the Overall Approach
      Easier For Designers to Construct
    • 19/28
      General Relationships
      <pclass=“2ColumnFloat”>
      <divclass=“CNN_AdBox”>...</div>
      </p>
      CNN_AdBox is Contained Within a 2ColumnFloat
      2ColumnFloat is Removable Therefore CNN_AdBox is Removable
      What If CNN_AdBox is Not Removable?
    • 20/28
      Class Containment
      High Priority
      Removable
      hasPriority
      isRemovable
      CNN_AdBox
      2ColumnFloat
      isContained Within
    • 21/28
      Only Within That Instance
      CNN_AdBox is Contained Within a 2ColumnFloat Only Within this Instance
      CSS Properties Can Still be Applied Even If CNN_AdBox is Not Contained Within 2ColumnFloat
    • 22/28
      A Little Testing Goes A Long Way
      Small Scale Testing Brings to Light Errors of Modelling
      Can not Expect To Know Everything Without Real World Case Studies
      Prevents Effort of Reengineering
      Prevents Loss of Faith in the Tool
    • 23/28
      Be Pragmatic
      Designers are Not Ontology Engineers
      Significant Overhead Will Hinder Adoption
      Balance Between Minimal Effort but Enough Knowledge to not be Hindered
    • 24/28
      New SADIe Architecture
      Application
      Structural Ontology
      HTML
      CSS
    • 25/28
      CSS Role Property
      2ColumnFloat{
      -uom-structural-role:LinkedMenu;
      ...
      }
      Add a New Role to the CSS
      Still Validates
      Explicitly States What the Class Represents
      Values Based on WAfA Ontology
      Ontology of Accessibility and Web Authoring Concepts
    • 26/28
      Benefits
      Less Overhead to Expose Semantics
      Non Destructive
      Still Provide Same Functionality
      New Transformations being Investigated
      Other Uses of the Exposed Semantics
      AiSC
    • 27/28
      Conclusion
      Visual Rendering Can Provide Semantic Information
      Semantics Can Be Used to Drive a Transformation Process
      Poor Design Decisions Can Hinder Flexibility and Adoption
      A Well Defined Model and a Little Pragmatism Goes a Long Way
    • Questions
      http://hcw.cs.manchester.ac.uk