by Roger May
Over the last few months VRML has become talked about more and more within the computing community. This article will briefly describe what VRML is and give some experiences of using it. It will also give some pointers to more information on the subject.
The Virtual Reality Modelling Language (VRML) is basically a way of distributing virtual worlds around a network in a portable form. At the moment these worlds are only made up of objects that do not have behaviour of their own or even a solid surface. The objects can however act as links to other objects in the network, eg a door could link to a model of the room behind the door, a television screen could link to an MPEG video. There are many possibilities as to what VRML can be used for. In a very short time VRML will be extended to support behaviours and collision detection and more interestingly virtual presence. This will allow multiple people to interact in the same VR model allowing collaborations to occur over world-wide networks.
The Visual Systems Group at the Rutherford Appleton Laboratory (RAL) runs a Virtual Reality facility and as part of this work we have been looking at distributed VR now and for the future. RAL collaborates with CERN in Geneva on a large project called the Atlas detector. As part of this work Lakshmi Sastry (firstname.lastname@example.org) has created a VR model of the end-cap designed by RAL using dVS/dVISE, a VR software package from Division Ltd. This model is used to assist the engineers and scientists in the design process. With the current VRML technology we can incorporate a VRML version of the model into the VR model of the rest of the detector held in Geneva. This will mean that someone viewing the model would see a model in which the geometry information is distributed around Europe. In the future the model could then be worked on in context, with engineers and scientists working on the same model over the network.
Converting from one VR system to another is not currently a simple process. Virtual Reality systems tend to be an end format rather than a transitional phase between formats. This means that creating a VRML version of a model created in the dVS/dVISE software is not a simple task. The main problem is the assembly of the parts that make up the model when they have come from different sources and were created using CAD systems that use different co-ordinate systems. The geometry information itself can be exported using standard tools via the DXF format into Inventor and then into VRML. These geometry files can then be linked together into the complete world by either writing VRML code directly or by using a 3D modelling package which can output VRML directly. There is a shortage of cheap packages that can be used to assist in this process. Most of the problems of course can be solved or reduced at source by making sure the objects use the same coordinate systems.
The main source of information about VRML are currently World Wide Web pages hosted all around the world. The following is a list of some we have found useful.
Information on the web:
Roger May -CLRC