VRML Dr. Alun Moon

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 –(

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 –Cube –Cylinder –Sphere –Cone Advanced shapes –Elevation grid Terrain modelling –IndexedFaceSet Generic shape –Extrusion Very powerful tool if used well. Lathe shapes Surfaces of revolution Advanced shapes –Elevation grid Terrain modelling –IndexedFaceSet 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 (x,y,z) Rotation –Axis and angle (x,y,z,  ) –Based on quaternons Scaling –orientation –non-uniform Transformations can be nested, giving a complex transformation hierarchy. Assemblies When combined with interpolators, can simulate joints.

Animation and interaction TimeSensor DragSensors –PlaneSensor –CylinderSensor –SphereSensor Interpolators –Coordinate – mesh –Position –Rotation –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 lightlight –Bezier patch extensionBezier Engineering uses –Models I developed while at the RCID, Newcastle University. Spray bottleSpray Mechanical animation.Mechanical CFD post processing. (470kb / 73kb)CFD Inverse kinematics.kinematics Beam mechanics (Wendy Parker)Beam

Other peoples models by Ivan Klíma –A good site of well built VRML models (by “hand” in text editor). Lathe demonstrationLathe Lunar siteLunar Boeing E3-A SentryBoeing University of Arizona –Virtual terrain (71kb / 12kb, texture 289kb)terrain Manchester Visualization Centre –Medical simulations

Other users and sites Paul Fishwick, University of Florida, VRML as an environment for engineering systems modelling NIST A number of projects using VRML for visualisation (search for VRML) A good site for reference and background material, links and tools VRML Repository A good place to find links to tools, and object libraries