University College Dublin1 Scope ROOT Light SourceTransform Light SourceSphere.

University College Dublin 1

Scope

ROOT

Light Source TransformTransform

Light SourceSphere

Sphere


3D on the Web If you want any kind of special lighting effect on a

surface, such as a spotlight with a soft edge, that surface will have to have many vertices on it and be made up of many faces, as VRML only does lighting at each corner.

This is a very important thing to remember. If you have a light shining on the middle of a large surface, you will not get the effect you want.


3D on the Web Just as HyperText Markup Language (HTML) led to a

huge increase in the use of graphics on the Internet by implementing a graphical interface

The VRML Consortium intend to add the next level of interaction, structured graphics, and extra dimensions (z and time) to the web

The VRML consortuin was created in 1994 It has created a standard for a Virtual Reality Modeling

Language (VRML)– often pronounced 'vermal’

– ISO Standardised in 96, (ISO VRML97)


History In 1994, Tim Berners-Lee invited Mark Pesce to present a

paper at the First International Conference on the World Wide Web

Pesce and partner Tony Parisi had developed Labyrinth, a prototype three-dimensional interface to the Web

His presentation sparked a consensus: the conference attendees agreed there was a need for a common language to specify 3D scene descriptions

Brian Behlendorf set up an electronic mailing list to facilitate discussion of the specification for VRML


History Within a month, there were over a thousand members The list membership quickly agreed upon a set of

requirements for VRML: – platform independence

– extensibility

– ability to work over low-bandwidth (14.4 kBps modem)

After much deliberation, the proto-VRML community selected the Open Inventor ASCII File Format from Silicon Graphics, Inc. as the basis of VRML

Some of the leading technical experts on the VRML mail list formed the VRML Architecture Group (VAG) in 95


Members The Web3D Consortium has 42 Corporate Members, 10

Charter Members, 12 Voting Members and 20 Non-Voting Associate Members– Microsoft Corporation, Apple Computer, Silicon Graphics, Inc.,

Sony Corporation, Hewlett-Packard, Philips Electronics, Sun Microsystems etc


Virtual Reality Modeling Language The Virtual Reality Modeling Language (VRML) is a file

format for describing interactive 3D objects and worlds Conceptually, each VRML file is a 3D time-based space

that contains graphic and aural objects that can be dynamically modified through a variety of mechanisms

VRML is designed to be used on the Internet, intranets, and local client systems


Virtual Reality Modeling Language A characteristic of VRML files is the ability to compose

files together through inclusion and to relate files together through hyperlinking

e.g consider the file earth.wrl specifies a world containg a sphere representing the earth– It may also contain references to a variety of other VRML files

representing cities on the earth (e.g., file paris.wrl)

– earth.wrl defines the coordinate system in which all cities reside

– Each city file defines its own world coordinate system that the city resides in that becomes a local coordinate system when contained by the earth file


Virtual Reality Modeling Language Hierarchical file inclusion enables the creation of

arbitrarily large, dynamic worlds Therefore, VRML ensures that each file is completely

described by the objects contained within it There are various objects and mechanisms built into the

language that support multiple distributed files, including:– in-lining of other VRML files;

– hyperlinking to other files;

– using existing Internet and ISO standards for other file formats;

– defining a compact syntax


Characteristics of VRML VRML is capable of representing

– Static and animated dynamic 3D

– multimedia objects with hyperlinks to other media such as » text

» sounds

» movies

» images

VRML browsers, as well as authoring tools for the creation of VRML files, are available for a number of different platforms– See links on last slide


VRML and Time The browser controls the passage of time in a world by

causing TimeSensors to generate events as time passes Specialized browsers or authoring applications may cause

time to pass more quickly or slowly than in the real world, but typically the times generated by TimeSensors will approximate "real" time

A world's creator should make no assumptions about how often a TimeSensor will generate events but can safely assume that each time event generated will have a timestamp greater than any previous time event.


VRML Light Shape nodes are illuminated by the sum of all of the lights

in the world that affect them– This includes the contribution of both the direct and ambient

illumination from light sources

Ambient illumination is from the scattering and reflection of light originally emitted directly by light sources

The amount of ambient light is associated with the individual lights in the scene

The following node types are light source nodes:– DirectionalLight

– PointLight

– SpotLight


Sensor nodes VRML contains the following concepts of sensors:

– Environmental sensors

– Pointing-device sensors


Environmental sensors The ProximitySensor detects when the user navigates into

a specified region in the world– The ProximitySensor itself is not visible

The TimeSensor is a clock that has no geometry or location associated with it; – it is used to start and stop time-based nodes such as interpolators

The VisibilitySensor detects when a specific part of the world becomes visible to the user

The Collision grouping node detects when the user collides with objects in the virtual world


Pointing-device sensors Pointing-device sensors detect user pointing events such

as the user clicking on a piece of geometry– i.e. TouchSensor

A pointing-device sensor is activated when the user locates the pointing device over geometry that is influenced by that specific pointing-device sensor


Navigation Conceptually speaking, every VRML world contains a

viewpoint from which the world is currently being viewed Navigation is the action taken by the user to change the

position and/or orientation of this viewpoint thereby changing the user's view

This allows the user to move through a world or examine an object


Navigation The browser may allow the user to modify the location

and orientation of the viewer in the virtual world using a navigation paradigm

Many different navigation paradigms are possible, depending on the nature of the virtual world and the task the user wishes to perform

e.g. a walking paradigm would be appropriate in an architectural walkthrough application, while a flying paradigm might be better in an application exploring interstellar space


Simple Example : Output


Further reading The information in this lecture is extremely changeable so

you must access the web for further reading– http://www.vrml.org/faq/faq.html

– http://www.vrml.org/Specifications/VRML97/

– http://www.sgi.com/Technology/Inventor/

– http://www.hyperreal.com/~mpesce/

– http://www.ch.ic.ac.uk./talks/www94_report.html

– http://www.vrml.org/vag


Further reading

VRML 1.0 Standard objects (cube,

sphere, cone, cylinder, text) Arbitrary objects (surfaces,

linesets, pointsets) Ability to fly through, walk

through, examine scenes Lights Cameras (viewpoints) Textures on objects Clickable links

Define and reuse objects

VRML 1.0 Standard objects (cube,

sphere, cone, cylinder, text) Arbitrary objects (surfaces,

linesets, pointsets) Ability to fly through, walk

through, examine scenes Lights Cameras (viewpoints) Textures on objects Clickable links

Define and reuse objects

VRML 2.0 All of VRML 1.0 plus Animated objects Switches Sensors Scripts (Java or JavaScript) for

behaviors Interpolators (color, position,

orientation, etc.) Extrusions Background colors and textures Sound (.wav and MIDI) Animated textures Event routing Define and reuse objects and

behaviors and effectively add new nodes to the language with PROTO and EXTERNPROTO

VRML 2.0 All of VRML 1.0 plus Animated objects Switches Sensors Scripts (Java or JavaScript) for

behaviors Interpolators (color, position,

orientation, etc.) Extrusions Background colors and textures Sound (.wav and MIDI) Animated textures Event routing Define and reuse objects and

behaviors and effectively add new nodes to the language with PROTO and EXTERNPROTO

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