University College Dublin1 Scope ROOT Light SourceTransform Light SourceSphere

University College Dublin2 3D on the Web u 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. u 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.

University College Dublin3 3D on the Web u Just as HyperText Markup Language (HTML) led to a huge increase in the use of graphics on the Internet by implementing a graphical interface u The VRML Consortium intend to add the next level of interaction, structured graphics, and extra dimensions (z and time) to the web u The VRML consortuin was created in 1994 u It has created a standard for a Virtual Reality Modeling Language (VRML) – often pronounced 'vermal’ – ISO Standardised in 96, (ISO VRML97)

University College Dublin4 History u In 1994, Tim Berners-Lee invited Mark Pesce to present a paper at the First International Conference on the World Wide Web u Pesce and partner Tony Parisi had developed Labyrinth, a prototype three-dimensional interface to the Web u His presentation sparked a consensus: the conference attendees agreed there was a need for a common language to specify 3D scene descriptions u Brian Behlendorf set up an electronic mailing list to facilitate discussion of the specification for VRML

University College Dublin5 History u Within a month, there were over a thousand members u 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) u After much deliberation, the proto-VRML community selected the Open Inventor ASCII File Format from Silicon Graphics, Inc. as the basis of VRML u Some of the leading technical experts on the VRML mail list formed the VRML Architecture Group (VAG) in 95

University College Dublin6 Members u 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

University College Dublin7 Virtual Reality Modeling Language u The Virtual Reality Modeling Language (VRML) is a file format for describing interactive 3D objects and worlds u 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 u VRML is designed to be used on the Internet, intranets, and local client systems

University College Dublin8 Virtual Reality Modeling Language u A characteristic of VRML files is the ability to compose files together through inclusion and to relate files together through hyperlinking u 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

University College Dublin9 Virtual Reality Modeling Language u Hierarchical file inclusion enables the creation of arbitrarily large, dynamic worlds u Therefore, VRML ensures that each file is completely described by the objects contained within it u 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

University College Dublin10 Characteristics of VRML u VRML is capable of representing – Static and animated dynamic 3D – multimedia objects with hyperlinks to other media such as » text » sounds » movies » images u 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

University College Dublin11 VRML and Time u The browser controls the passage of time in a world by causing TimeSensors to generate events as time passes u 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 u 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.

University College Dublin12 VRML Light u 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 u Ambient illumination is from the scattering and reflection of light originally emitted directly by light sources u The amount of ambient light is associated with the individual lights in the scene u The following node types are light source nodes: – DirectionalLight – PointLight – SpotLight

University College Dublin13 Sensor nodes u VRML contains the following concepts of sensors: – Environmental sensors – Pointing-device sensors

University College Dublin14 Environmental sensors u The ProximitySensor detects when the user navigates into a specified region in the world – The ProximitySensor itself is not visible u 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 u The VisibilitySensor detects when a specific part of the world becomes visible to the user u The Collision grouping node detects when the user collides with objects in the virtual world

University College Dublin15 Pointing-device sensors u Pointing-device sensors detect user pointing events such as the user clicking on a piece of geometry – i.e. TouchSensor u A pointing-device sensor is activated when the user locates the pointing device over geometry that is influenced by that specific pointing-device sensor

University College Dublin16 Navigation u Conceptually speaking, every VRML world contains a viewpoint from which the world is currently being viewed u Navigation is the action taken by the user to change the position and/or orientation of this viewpoint thereby changing the user's view u This allows the user to move through a world or examine an object

University College Dublin17 Navigation u The browser may allow the user to modify the location and orientation of the viewer in the virtual world using a navigation paradigm u Many different navigation paradigms are possible, depending on the nature of the virtual world and the task the user wishes to perform u 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

University College Dublin18

University College Dublin19

University College Dublin20 Simple Example : Output

University College Dublin21 Further reading u The information in this lecture is extremely changeable so you must access the web for further reading – – – – – –

University College Dublin22 Further reading VRML 1.0 u Standard objects (cube, sphere, cone, cylinder, text) u Arbitrary objects (surfaces, linesets, pointsets) u Ability to fly through, walk through, examine scenes u Lights u Cameras (viewpoints) u Textures on objects u Clickable links u Define and reuse objects VRML 1.0 u Standard objects (cube, sphere, cone, cylinder, text) u Arbitrary objects (surfaces, linesets, pointsets) u Ability to fly through, walk through, examine scenes u Lights u Cameras (viewpoints) u Textures on objects u Clickable links u Define and reuse objects VRML 2.0 All of VRML 1.0 plus u Animated objects u Switches u Sensors u Scripts (Java or JavaScript) for behaviors u Interpolators (color, position, orientation, etc.) u Extrusions u Background colors and textures u Sound (.wav and MIDI) u Animated textures u Event routing u 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 u Animated objects u Switches u Sensors u Scripts (Java or JavaScript) for behaviors u Interpolators (color, position, orientation, etc.) u Extrusions u Background colors and textures u Sound (.wav and MIDI) u Animated textures u Event routing u Define and reuse objects and behaviors and effectively add new nodes to the language with PROTO and EXTERNPROTO