PII: SOOlO-4485(97)00016-6

Cornpurer-Aided Dewgn, Vol 29. NO 8, pp. 543-545, 1997 ? Published by Elsevier Science Ltd All rights reserved

Pmted m Great Britain OOlO-4485/97/$17.00+0.00

Editorial

Special Issue: Virtual reality

In very simple terms, virtual reality (VR) refers to a synthetic or virtual environment that gives a person an illusion of reality. This definition would include any synthetic environment which gives a person a feeling of ‘being there’. Most commonly, however, VR refers to computer-generated synthetic environments. The expo- sure most people have to virtual reality is through reports in the media, through science magazines and through science fiction. However, to researchers involved in the science of virtual reality, the applications are much more mundane and the problems are much more real.

What separates virtual reality from traditional com- puter graphics? According to many researchers, ‘if you are not immersed, it is not VR’. The feeling of immersion is identified as the most important feature of VR, separating it from other forms of computer-aided simulations.

Virtual reality hardware and software

Several advanced hardware and software systems come

together in any typical VR application to make this immersion possible. Helmet-mounted displays (HMDs) provide the user with a stereo-scopic view of the computer- generated environment. These HMDs also typically block out the user’s peripheral vision to make the sense of isolation complete. Tracking devices (typically electro- magnetic sensors) attached to the body of the user allow the computer to track the user’s movements. These movements are used (in real time) to modify the display seen in the stereoscopic display. Human models repre- senting the user follow the motions tracked by the sensors. Instrumented gloves and body suits are used for more articulate motions. Tactile and kinesthetic feed- back devices provide users with touch and force sensations. Headphones and 3D sound systems provide audio feedback to the user.

Several software toolkits (e.g. World Toolkit, d-Vise, etc.) are available to support the creation of virtual environments. Some applications programmers prefer to use graphics libraries (such as Open GL, Performer, PHIGS. etc.) instead of these specialized toolkits. Some inexpensive systems provide device drivers for the specialized VR hardware.

Virtual reality user

Editorial

Caterpillar’s vitual prototyping system

CAD/CAM appk&iOnS Of VR

Although graphics hardware and software systems have been available since the 1960s the creation of commer- cial, interactive CAD/CAM systems started only in the 1970s. Wide-scale use of interactive CAD/CAM systems started only in the mid-1980s. One reason for this delay between computer graphics and interactive CAD was the lack of proper CAD software. Initial CAD systems put the drafting board on a computer. Although this in itself was a big advantage, the true power of CAD began to be realized only through developments in geometric model- ing, parametric design, variational geometry, and feature- based design. The use of CAD:CAM is now so widespread that no single commercial CAD system can meet all the needs of the user community. Most CAD/CAM users either create customized software or tailor commercial soft- ware products to suit their specific needs.

Virtual reality is at a similar crossroads. Several small groups of researchers are beginning to apply VR to solve engineering design and manufacturing problems. How- ever, widespread use of this new technology will come only with the availability of proper commercial software systems. All current CADCAM applications of VR are custom-created from scratch. Some commercial products are following the path of initial CAD tools-taking existing CAD technology and throwing it into a VR environment without any significant changes in the tools used for design.

In this issue

Virtual reality brings a completely new human interface technology to the CAD/CAM community. Some of the immediate and initial benefits to design and manufactur- ing are being brought about by improved user interfaces for the creation and modification of designs, evaluations of designs for functionality and manufacturability by

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putting a ‘human in the loop’, and simulation of manu- facturing environments. This special issue of Computer- Aided Design brings together a carefully selected set of research efforts aimed at these issues related to the application of VR to computer-aided design. The paper by Mine discusses the overall issues of user interfaces using virtual reality techniques. It discusses ISAAC, a meta-cAo system for virtual environments.

The paper by Dani and Gadh describes an effort (COVIRDS) aimed at using virtual reality interfaces to provide an advanced, multi-modal interface for the creation of shapes for conceptual design. The paper by Trika, Banerjee and Kashyap describes the use of VR in feature-based CAD systems. The paper by Connacher, Lyons and myself describes the use of virtual reality for assembly evaluations and planning. This effort describes the integration of the customized virtual environment (VADE) and commercial, parametric CAD systems. Finally, the paper by Gupta, Whitney and Zeltzer describes another assembly planning system (VEDA) which incorporates multi-modal virtual environments into assembly planning.

In the future

The use of virtual reality to support computer aided design is rapidly increasing in industry. Caterpillar, General Motors, Boeing Corporation, Ford Motor Company, Benz, and British Aerospace are examples of industry leaders applying VR to support design, analysis, and manufacturing. The Computers in Engineer- ing Division of the American Society of Mechanical Engineers has created a new technical area called ‘Virtual Environments and Systems’. There is an annual ASME conference in which recent developments in the applica- tion of VR to engineering are presented. IS0 standards committees are evaluating various technologies in an attempt to facilitate the standardization of data transfer

Editorial

and applications programming interfaces to support VR applications.

Although virtual reality was first demonstrated in 1965, most of the advances in this technology have come about only in the 1980s and 1990s. Thus, it can be regarded as a new technology which is changing and maturing almost every day. Although this technology is

relatively immature, now is the appropriate time for application users to start using this technology and help drive it in the direction to needs to go to support their CAD CAM applications.

Sankar Ja~,amm Washington State University