What is VRML The Virtual Reality Modeling Language VRML is a file format for describing interactive 3D objects and by HC120613135525

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									     VRML

   Dr. Alun Moon
alun.moon@unn.ac.uk
                 What is VRML
The Virtual Reality Modeling Language (VRML) is a file format for
describing interactive 3D objects and worlds. VRML is designed to be
used on the Internet, intranets, and local client systems. VRML is also
intended to be a universal interchange format for integrated 3D
graphics and multimedia. VRML may be used in a variety of
application areas such as engineering and scientific visualization,
multimedia presentations, entertainment and educational titles, web
pages, and shared virtual worlds.
     – From the VRML specification
     – Web3D consortium – source of the VRML specs
       http://www.web3d.org/
     – (http://www.web3d.org/fs_specifications.html)
                          Features
Extensible
 – New nodes can be created using a PROTOTYPE mechanism
Dynamic
 – Interaction and animation is achieved via an event model, behaviour can
   be programmed in Java and JavaScript (ECMAScript)
Compact
 – Descriptions of geometry can be compact, using a reuse mechanism.
    High compression ratios are achieved with gzip.
Text file
 – Tools for revision control and versioning, compilation and automatic
   generation, can all be used.
                   Concepts: Geometry
   • Basic shapes         • Advanced shapes
        –   Cube             – Elevation grid
        –   Cylinder             • Terrain modelling
        –   Sphere           – IndexedFaceSet
        –   Cone                 • Generic shape
                             – Extrusion
                                 • Very powerful tool if used well.
                                 • Lathe shapes
                                 • Surfaces of revolution

No constructive solid
   geometry, but shapes
   can occupy the same
   volume.
      Concepts: Transformations
• Translation                   • Transformations can be nested,
   (x,y,z)                        giving a complex
• Rotation                        transformation hierarchy.
   – Axis and angle (x,y,z,)   • Assemblies
   – Based on quaternons        • When combined with
• Scaling                         interpolators, can simulate
   – orientation                  joints.
   – non-uniform
        Animation and interaction
• TimeSensor                        • Interpolators
• DragSensors                            –   Coordinate – mesh
    – PlaneSensor                        –   Position
    – CylinderSensor                     –   Rotation
    – SphereSensor                       –   Scalar
                                    • Bounded linear interpolation


Event model.
    Event outputs (sensor outputs) can be routed to nodes to set parameters (e.g.
      rotation). A complex interaction model can be constructed.
                     Model creation
• Text editor
    – Good for learning VRML.
    – Often used for tidying VRML and adding behaviour.
• Automatic generation
    – Large model generation from data file, script can generate VRML from
      data.
        • Custom perl scripts
        • Macro tools m4, cpp ?
                   Commercial tools
• CAD export
    – Some only produce VRML 1.0, and quality can be poor
         • Pro/Engineer
         • AutoCAD
• 3D modelling tools
    – Good geometry and texture editing, less capable in some respects than
      CAD
         • 3D Studio Max
• Analysis tools
    – Visualisation of scientific data
         • Matlab
         • Fluent (next version)
                        Some models
• Basic models
   – Basic light
   – Bezier patch extension
• Engineering uses
   – Models I developed while at the RCID, Newcastle University.
       •   Spray bottle
       •   Mechanical animation.
       •   CFD post processing. (470kb / 73kb)
       •   Inverse kinematics.
       •   Beam mechanics (Wendy Parker)
             Other peoples models
• by Ivan Klíma http://vrml.environs.com/ivan/
    – A good site of well built VRML models (by “hand” in text editor).
        • Lathe demonstration
        • Lunar site
        • Boeing E3-A Sentry
• University of Arizona http://ag.arizona.edu/agnet/vrml/
    – Virtual terrain (71kb / 12kb , texture 289kb)
• Manchester Visualization Centre
    – Medical simulations http://synaptic.mvc.mcc.ac.uk/simulators.html
              Other users and sites
• Paul Fishwick, University of Florida,
  VRML as an environment for engineering systems modelling
  http://www.cise.ufl.edu/~fishwick/vrml/
• NIST
  A number of projects using VRML for visualisation
  http://www.nist.gov/ (search for VRML)
• A good site for reference and background material, links and tools
  http://hiwaay.net/~crispen/vrmlworks/
• VRML Repository
  A good place to find links to tools, and object libraries
  http://www.web3d.org/vrml/vrml.htm

								
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