Virtual Reality Modeling Language (VRML)

by Steve Carson, GSC Associates Inc., carson@siggraph.org

ISO/IEC JTC1/SC24 (Computer Graphics and Image Processing) is developing a family of 3D graphical metafile standards. The first of these is based on the Virtual Reality Modeling Language, Version 2.0 (VRML 2.0) specification developed by the VRML community under the leadership of the VRML Architecture Group (VAG). VRML 2.0 is based on the Moving Worlds specification submitted by Silicon Graphics to the VRML community in response to the VRML 2.0 Request for Proposals.

The Virtual Reality Modeling Language (VRML) is a file format for describing three-dimensional interactive worlds and objects. It can be used in conjunction with the World Wide Web. It is used to create three-dimensional representations of complex scenes such as illustrations, product definitions, and virtual reality presentations.

VRML is capable of representing static and animated objects and it can have hyperlinks to other media such as sound, video, and image. Interpreters (browsers) for VRML are widely available for many different platforms as well as authoring tools for creating VRML files. VRML supports an extensibility model that allows new objects to be defined and a registration process to allow application communities to develop interoperable extensions to the base standard.

VRML was designed to fulfill the following requirements:

• Authorability: VRML should make it possible to develop application generators and editors, as well as to import data from other industrial formats.
• Composability: The elements of VRML should be able to be used in combination and thus result in re-usability.
• Extensibility: VRML should have the ability to add new elements.
• Implementability: The VRML specification should provide full information for implementation and therefore contain no ambiguities.
• Multi-user potential: The VRML specification should not preclude the implementation of multi-user environments.
• Orthogonality: The elements of VRML should be independent of each other, or any dependencies should be structured and well-defined.
• Performance: The elements should be designed with the emphasis on interactive performance on a variety of computing platforms.
• Scalability: All elements should have a limited scope and therefore no global effect.
• Standard practice: Only those elements that reflect existing practice, that are necessary to support existing practice, or that are necessary to support proposed standards should be standardized.
• Well-structured: An element should have a well-defined interface and a simply stated unconditional purpose. Multipurpose elements and side effects should be avoided.

The scope and field of application of VRML includes:

1. A mechanism for storing and transporting two-dimensional and three-dimensional data;
2. Elements for representing two-dimensional and three-dimensional primitive information;
3. Elements for defining the characteristics of such primitives; elements for viewing and modeling two-dimensional and three-dimensional information;
4. A container mechanism for incorporating data from other metafile formats; and
5. A mechanism for defining new elements which extend the capabilities of the metafile to support additional types and forms of information.

VRML Status in ISO

At its July 1996 meeting in Kyoto, Japan, JTC1/SC24 agreed to publish the final (August 1996) version of VRML 2.0 as Committee Draft (CD) 14772. The CD ballot is currently underway and will close in November, 1996. After a comment resolution process conducted jointly with the VRML Architecture Group, the DIS text is expected to be ready in December 1996. Following a four month ISO DIS ballot, VRML 2.0 should be forwarded for publication as an ISO standard in May 1997 at the SC24 meeting at Kista, near Stockholm, Sweden. The text will be published electronically as an HTML document and will mark the first time that an ISO standard has been so published.

The text of CD 14772 (VRML) can be retrieved from: http://vag.vrml.org/VRML2.0/FINAL or from http://vrml.sgi.com/moving-worlds.

For further information about the work of ISO/IEC JTC1/SC24 (Computer Graphics and Image Processing) you may consult the committee's home page at http://www.cwi.nl/JTC1SC24.

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