Getting behind the hype surrounding virtual reality can be hard work - much of it revealing only a hazy grasp of the real technology involved. Will there be virtual entertainment? Virtual travel? CYBERSEX? Not just yet, it seems. So where are we now? And how easy is it to get into "VR" with a more modest budget than NASA?
Where we are now is just at the point where a fledgling technology is being taken seriously, like the movies at the turn of this century. In the research world, they hype is over bar the copyright and patent battles, which are only just beginning. Virtual reality has a definition as a three-dimensional, computer-generated environment rendered in real-time according to the actions of the user. VR engages sight, sound and your other senses directly to create the illusion of immersion in another world. The argument rages over whether looking at a 3D world through a screen constitutes "real" virtual reality, but despite the fact that virtual worlds look a whole lot better in a big, expensive monitor, a growing consensus says it is not the picture that counts, but what you can do with the picture - or rather, IN the picture. This costs money, and the big players like NASA and the US military have thousands of dollars to throw at their projects. But what if you wanted to cook a little home-brew virtual world of your own? Where would you start?
Firstly, we need to quickly consider the technical requirements of virtual reality. A 3D world is built up from a software description of its geometry, then drawn in real time by the computer. Every part of the picture is made from polygons, the surfaces of which can be coloured, shaded and even textured - this is known rendering. The more polygons in the picture, and the more detailed the rendering, the more powerful the hardware needs to be to drive the system. But this isn't all. To give the illusion of movement, the picture has to be drawn several times per second to simulate motion, like film or video - preferably at 24 frames per second or more. Now if a VR system claims 30,000 polygons per second, that's fine if the picture is static. But what if the viewer looks around or starts to move? At 30 frames per second, the picture is now limited to somewhere between 1000 and 5000 polygons per frame, or the frame update rate has to drop, and the image becomes jerky. This trade-off between polygon count and frame rate is potentially solvable - it just means throwing money at the hardware. But in the meantime it places severe limitations on low-cost VR systems, as does the need to allow as wide a field of view as possible. A 60 degree field of view is roughly equivalent to a movie screen. Less, and it feels like you are looking through blinkers. More than 90 degrees begins to engage peripheral vision and makes it feel "real". Again, a cost factor. And if roughly 60% of our awareness is by sight, what about other senses, like sound and touch?
Face it. You are not going to stroll the streets of your virtual San Francisco with an elderly computer and £20 in your pocket. The first question you have to ask yourself is "Are you feeling rich?" If the answer is yes, read on. If not, I'll get to you later....
To "immerse" the user in a virtual world means shutting out the real one as totally as possible. Until very recently, enclosed head-mounted displays (HMDs) have been expensive, £2000 and more, and mostly for use in research, by the military or in "pay-by-the-play" arcade machines. But the last quarter of 1994 sees the release of two systems that are likely to change both the cost and our perception of VR. The CyberMaxx and the Forte VFX1 are volume sale add-ons for personal computers, targeted at £600 or under and on sale from white goods outlets like Dixons. Both work by placing two miniature liquid crystal displays just in front of your eyes and viewed through diffusing and focusing lenses. Both accept standard VGA computer graphics and stereo sound. Both provide real-time head movement tracking with 6 degrees of freedom (roll, pitch and yaw) in 360 degrees on the horizontal plane. Both offer the kind of visual resolution and quality that would have cost ten times as much just a year ago.
The CyberMaxx is likely to be the cheaper of the two, at around £500, possibly less. The intended platform is the IBM PC, but Macintosh, Sega and possibly the Atari Jaguar and Commodore Amiga may also be supported. It has a greater horizontal and vertical field of view than the Forte, but a resultant slight reduction in picture quality. It is "TV-ready", if you really want to watch very low-resolution TV, but it is more obviously targeted at the home computer games and multimedia market. The parent company, VictorMaxx, are also developing a 3D joystick and will probably be marketing hard for Xmas. Forte's VFX1 headset will cost around another £200 or so, but Forte are bundling the CyberPuck 3D controller in the pack, and motion tracking is not a cheap technology. The VFX1, which is currently IBM PC compatible only, does seem to promise better visuals than the CyberMaxx, partly by sharing some of the processing via its own interface card and partly at the expense of field of view. At this point, it should be said that there are still some serious health and safety worries about using equipment that forces you to focus almost cross-eyed for long periods of time, and that has a visual resolution so poor that you are legally blind. Nevertheless, the low cost and PC compatibility of the Forte and the CyberMaxx headsets signal an exciting new phase for home entertainment and for low cost virtual reality systems of all kinds. At just over the £1000 mark is another 3D viewing technology entirely; the CyberEyes shuttered glasses, which allow the wearer to see "into" a standard computer screen in 3D by synchronising the shuttering of the left/right image in the glasses with equivalently displaced stereo images on the screen. Not immersive like an HMD, "looking through the magic window" is more a "demos and presentations" technology, that may yet drop in price if it find its place in schools and 3D design. At the utterly budget end of the market, watch out for the now-obselete Sega shuttered glasses, for use with Sega game consoles and still occasionally available in stock clearances or second-hand. With appropriate adaptors, it can be hooked up to a PC, and if you are fond of blurred, grainy, incomprehensible images, this might be just the thing for you...
Surround sound has been with us for a while in the cinema, and more recently in home audio-visual systems. Currently, it is making it's way into the latest generation of computer-based sound reproduction hardware and software and from there into virtual reality systems. Again, the "IBM compatible" Intel 80386-486 PCs provide the basic platform for low-cost digital sampling, spatial stereo, and MIDI control, with the Apple Macintosh and PowerPCs, and the Atari Falcon competing strongly. (MIDI is the Music Industry Digital Interface - a specification for software that controls musical instruments, but can also be used to synchronise and control other peripheral audio devices like mixers, effects and even stage lighting.)
The latest manifestation of 3D sound is Creative Lab's licence of Q-Sound from Archer Comms Inc. Creative Labs have adopted an algorithm that supports 32 Q-sound pan positions to create a full 180 degree soundscape using 8,11.25, 22.5 and 44.1 khz (CD-quality) sample playbacks, without any special hardware or software. This software-only system for DOS and Microsoft Windows is potentially amazing. Using standard stereo hardware and highly accurate sound spatial distribution, Q-Sound can provide a soundscape that exceeds the physical bounds of conventional stereo speaker geometry. Q-Sound can be implemented in two ways: as a post-production add-in to a recording studio's final mix or as control data in real-time sound processing by computer sound boards. Both then create the 3D effects through an ordinary stereo amplifier and speakers, though the placing of speakers in relation to the listener, volume levels, sound field and reflection from walls are all critical to clear perception. The advantage of Q-sound in VR is that it allows interactive control of sound effects - if the listener changes position in relation to a sound in the virtual world, the spatial image can be altered as effectively as the visual one. All the Creative Labs sound cards with Advanced Digital Signal Processing can support Q-sound, and Creative's AWE 32 sound card can also emulate Q-Sound pan data for MIDI playback. so in theory you could program music that appeared to have the musicians running around you - or at least from side to side (until Q-Sound supports a full 360 degree soundscape). The Ultrasound sound card from Gravis also supports a 3D soundscape system, but it is currently not as well implemented as Q-Sound; there are only 3 separate autopan positions, compared with 32 for Q-Sound, though expect to see Q-Sound's present pole position in low-cost 3D sound challenged heavily over the next year.
When Jaron Lanier's company VPL folded in 1992, the battle ensued over patent rights to the DataGlove - once pitched as the "ultimate" interface to virtual reality. The DataGlove mirrored hand movement to the computer, and in some cases could be programmed to provide "force-feedback"; an illusion of touch. Now nobody is making glove-style interfaces, just in case they infringe the VPL patents. The current alternatives are various, depending on whether you want to move around a world in real-time, or to interact for design purposes. At the expensive end of the market is the Spaceball, a motion-tracked orange-sized sphere that can move a cursor in 3D, and a motion trackers that can be attached to joysticks and mice from Polhemus and Ascension in the USA. Logitech, famous for PC mice and scanners, have a variety of 6 degrees of freedom controllers, including a cordless 2D/3D "flying mouse" that can be used on the tabletop or in the air (rather like Thunderbirds), and a static desktop device that operates like a spring-loaded trackball. Neither are cheap. However, Logitech's latest addition to their range promises a good, low-cost entry device for home VR. Called the CyberMan, and retailing at "less than £75", this "mouse on a stick" is an interesting compromise, providing full 6 degrees of freedom through a standard interface. In use, the CyberMan is initially difficult to master; it is very sensitive, and the base needs to be fixed firmly. I also found that the base did not offer as much wrist support as I would have liked, though with use, the CyberMan becomes more intuitive. Again, where Logitech lead the way, we can expect competition, especially in the field of games input devices. (Indeed, for a while Mattel had a licence to Make "PowerGloves" - a simple glove input for Nintendo games. Though no longer in production, some of these gloves are still around, and PC adaptors available for them - both highly prized additions to a home-brew VR system.)
So how do we put all these hardware components together to build
virtual environments? The good news is that suitable software is
available virtually free as "public domain" packages that anyone can use
without licensing, and some cheap commercial packages are available. The
bad news is that few are particularly easy to use. These are not 3D
drawing programs - they allow you to move around the image in real-time,
rather than just creating the image to look at or to animate. "REND386"
by Canadians Dave Stampe and Bernard Roehl started out as a 3D design
package, "grew" extensions to allow use for VR, and mutated into "VR386",
a dedicated public domain VR package. It is freely available from a
variety of Internet file transfer sites, (try: FTP
The sleeper hit PC game of 1994 has been id software's Doom, a 3D first-person view shoot-em-up of extreme, X-rated violence, that can allow up to four players to participate together. You see each other as animated soldiers and can work together to defeat the monsters, or play in self-explanatory DeathMatch mode. It's a sleeper because it is has had little advertising and it is try-before-you-buy shareware - you get Part 1 of Doom free, then register for the next two episodes. Because id made some of their programming specifications freely available, a whole heap of Doom map builders and editors have materialised for enthusiasts to create their own worlds and add their own graphics to the registered version. Be warned: Doom is not "true" 3D. It works by "ray-casting" across a 2D map, scaling and animating the perspective view, then inserting and scaling bitmap graphics and short animated routines. Doom is really a 2D game. The map is flat, you can appear to be at any level height-wise, but you can only occupy one space on the plane of the map and you can only move to the next space if it isn't occupied by part of the scenery or a baddie. Despite these limitations, it looks good, so building your own Doom world can be considered a quick and dirty entry point for would-be VR world-builders.
Registered Doom is available from Virgin Games, HMV and major shareware suppliers. Various Doom editors, are available from Transend Shareware on (0274) 62228. Shareware Doom files and editors are also available on the Internet by anonymous FTP from:
ftp://infant2.sphs.indiana.edu/pub/msdos/games/IDGames..
and the UK FTP mirror site:
The best work in VR is still expensive, time consuming and going on behind closed lab doors. But as a taster of things to come, watch out for the Virtual Retinal Display (VRD) - a radical new display device in which the image is drawn directly on the retina of the viewer's eye. The four year program at the Univeristy of Seattle HIT Lab, funded by Micro Vision, Inc., USA, began in November 1993 with the goal of producing a full colour, wide field-of-view, high resolution, stereo display in a package the size of conventional eyeglasses. A prototype VRD demonstrated in early 1994, achieved fast horizontal scanning with an acousto-optical scanner, using optics to shape the input beam for deflection and then additional optics to reform the output beam to the desired shape. Now, HIT Lab engineers have developed a cheaper, proprietary mechanical resonant scanner. This scanner provides both horizontal and vertical scanning, with large scan angles, in a miniaturised package and the estimated bulk manufacturing cost will allow the VRD system to be priced competitively with other displays. A prototype using the new scanner has been built and demonstrated, where the optical system is greatly simplified, allowing the device to be considerable smaller and easier to focus then the original prototype. In addition, the image sharpness and contrast have been improved and the addition of a green light source allows the display to produce multi-coloured images. Apart from painting the image right into our eyes, retinal scanning could be used to augment VR so that selective parts of your real-world view had virtual elements superimposed - Roger Rabbit comes to life in your living room. Or an Alien. But of course, you can always switch off... can't you?
Garage Virtual Reality: The Affordable Way To Explore Virtual Worlds by Linda Jacobson (1994), published by Sams/Prentice Hall. Readably everything you need to know, from choice of software down to building your own headset using LCD displays from micro-TVs.
Virtual Reality Creations by Dave Stampe, Bernard Roehl and John Egan (1993), published by Waite Group Press. The writers of VR386 and REND386 share tutorials and tips; software included. The Virtual Reality Playhouse by Nicholas Lavroff (1992), published by Waite Group Press. Simple introduction, with a disk of out-of-date demos. Worth a look. (Remember, to do any successful dabbling with most public domain VR software, you will need to be a competent programmer, preferably in C or C++)ftp.u.washington.edu/public/virtual-worlds
sunsite.unc.edu/pub/academic/computer-science/virtual-reality
Ivor Benjamin is a systems analyst and a theatre director. He is conducting research into interactive virtual reality systems at the Centre for Human-Computer Interaction, City University, London. You can contact him by e-mail at ivorb@cix.compulink.co.uk ivorb@cix.co.uk or i.d.benjamin@city.ac.uk
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