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This column will be a regular feature over the next few issues. It will focus on aspects of 3D graphics over the Internet, and more specifically, VRML and Java3D. The column will report on the VRML / Java3D Information Centre project, funded by AGOCG and based at the University of Leeds. The project will offer information and support through Web pages, briefing reports and an e-mail list, on these two emerging technologies.
The Web page URL is:
http://www.scs.leeds.ac.uk/vrmljava3d
In addition, AGOCG is joining the VRML Consortium on behalf of the UK Higher Education Community, and will therefore have early access to future VRML developments.
If you are using VRML, or have an interest in Java3D, why not e-mail us and tell us what you are doing? One of our aims is to create a network of UK VRML / Java3D people.
In this first article, we reflect on the standardization of VRML through ISO.
Over the past twenty years, ISO have developed a family of graphics standards, including GKS, PHIGS and CGM. These standards have been developed by a lengthy committee process, where members of the ISO committee have largely initiated, designed and developed the specification into a final form, over a period of years.
This process is no longer viable in a world where the technology is moving very fast, and where more agile, de facto standardization of company products (such as OpenGL) has an obvious attraction.
However, VRML has been standardized in a radical way. The VRML Consortium, the guardians of VRML, have been accepted by ISO as a supplier of a Publicly Available Specification, or PAS. Hence the VRML document entered the ISO process in Autumn 1996 as a specification seen as 'finished' by the VRML Consortium. The role of ISO has been to work with the Consortium to ensure the specification has a clarity and consistency appropriate for a standards document. This has still taken rather a long time, but the end result is widely agreed to be a far superior document.
The revision process has had to work within a strait-jacket: commercial pressures on the VRML Consortium have forced them to take a stance whereby they vetoed any changes that would 'break' existing VRML words - so 'Color' remains 'Color' and not 'Colour'! - and whereby they resisted any changes that would 'break' existing VRML browsers.
Yet within those constraints major improvements have been made: the descriptive part of the document has been entirely restructured, and largely rewritten, to be more easily understood; the specification of each VRML node has been reorganized so that, for example, valid ranges of fields (or parameters) are explicitly stated in the heading (rather than having to be searched for in the description of the node); and a proper conformance section has been added.
The UK contribution to this work has been largely funded by AGOCG through a workshop that gathered a set of comments on the first draft, and through attendance at subsequent ISO Meetings.
The finished specification, known as VRML97, can be found at:
Ken Brodlie
kwb@scs.leeds.ac.uk
Stuart Lovegrove
stu@scs.leeds.ac.uk
