his year, for the first time, some military medic training sessions on gunshot wound treatments required no bloody cleanup. Instead of relying solely on wounded animals, medic trainees practiced techniques by guiding simulated instruments through simulated human tissue.
Watching a three-dimensional impression of a leg wound on a high-resolution computer monitor, a trainee holds a surgical instrument handle attached to a motion-sensing device. The tip of the instrument appears on the computer screen, and every movement of the handle results in a corresponding move of the simulated tip. The simulated flesh reacts to the tip as real flesh would under the same circumstances. But the results are much less messy.
The simulated exercises do more than save cleanup time. Hundreds of animals will be spared, and, more importantly for the military, the medics will have received more realistic training. "It will be real human anatomy they're practicing on," says Col. Rick Satava, M.D., program manager of Advanced Biomedical Technologies for the Defense Department's Advanced Research Projects Agency (ARPA). And "when you give a gunshot wound to an animal, you only get to practice on one wound, whereas with a virtual cadaver you can give it many different kinds of wounds and be able to practice [a procedure] over and over."
Medical training, both within and outside the government, is one of a growing number of areas in which virtual reality technology has moved from research laboratories into the real world. Virtual reality "is not the pie-in-the-sky fringe thing it was perceived as three to five years ago," says Daryl Rasmussen, a researcher at NASA's Ames Research Center, which has been at the forefront of research in this field. "People are doing real work using the technology," he says.
Varied Techniques
Virtual reality technology allows people to interact in three-dimensional, computer-generated environments. These are usually models of real-world scenes, but can also represent abstract data, such as budget figures. "In an ideal virtual environment, all of the senses are fully exploited such that it's difficult to differentiate between the real and the virtual world," says Bob Voiers, director of Electronic Data Systems Corp.'s Detroit Virtual Reality Center.
When virtual reality users move their heads, their views shift and sounds may be adjusted. Users can move around and sometimes through the objects they see. With the proper equipment, they can also pick things up, manipulate them and actually get the sensation of feeling the object in their hands. There is a two-way interaction: Users experience the virtual surroundings, and the surroundings and objects change in response to users' actions.
Not all virtual reality applications completely immerse users in artificial environments, nor is absolute realism necessary for a virtual reality application to be effective. Immersive applications rely on head-mounted displays with tracking sensors, gloves or other sensing devices. Popular in the entertainment sector, immersive virtual reality is used to design expensive equipment such as aircraft engines. Jackie Fenn, a research director at the Gartner Group, a Stamford, Conn.-based information technology advisory firm, expects the technique to become more important in applications that focus on exploring models of physical or abstract spaces.
More limited virtual reality applications allow users to interact with three-dimensional objects on a computer screen without making users feel surrounded by the environment. These cost-conscious alternatives to immersive virtual reality are popular for industrial design, architecture and data visualization, Fenn says.
Other virtual reality techniques involve projecting computer-generated images onto the walls of small rooms-useful for simulating vehicle-based views and engaging multiple users-or viewing the real world through glasses that superimpose relevant virtual objects such as schematic diagrams onto the scene. The latter technique is in its early stages, but has applications in maintenance and repair, as well as in the medical field, Fenn says.
Another technique, telepresence, allows users to see and influence a real but geographically removed scene; camera images reconstruct the scene for the user, who interacts with the remote environment by controlling on-the-scene robotic arms. Applications include remote surgery and exploration of distant environments.
Technology Still Developing
Virtual reality simulations are improving, but "most applications haven't tried to mimic all of the senses, because the result would be abominably bad," says Paul T. Breen of MITRE Corporation, a Bedford, Mass.-based nonprofit company that provides technical support to the government.
Most development work has focused on the visual component. But "with most virtual reality technology, you're legally blind at this point," Breen says. "It's got a long way to go." This is less of a setback for applications that depend more on object context than visual precision. Visual representations have improved: "All medical applications now suffer from a lack of visual realism, but it's much better than the cartoon levels you had a couple of years ago," ARPA's Satava says.
Generating computer scenes on the spot is less a technology problem than a problem of acquiring the necessary data sets and being able to afford the computer equipment. Powerful computers and better graphical representation techniques will make visual displays smoother, faster and more detailed. Falling computer costs also will put better graphics within reach.
Currently, a virtual-reality-enabled computer system can cost about $250,000; "in the next year, we'll see PC systems with similar kinds of capabilities probably on the order of $10,000," says John Latta, president of 4th Wave, a market analysis and consulting firm in Alexandria, Va.
Virtual reality applications stimulate the other four senses to varying degrees. Audio technology is "quite mature," Voiers says, at least with respect to incorporating three-dimensional sound in a virtual environment. The problem of how to make the computer respond to the human user's voice is harder to solve, although a lot of work is also being done in this area. The technology to reproduce tactile sensations is also "pretty primitive," Breen says.
Wide Applications
A 1994 National Research Council study noted that virtual reality could have practical uses in many fields, but especially in training, hazardous operations, medicine and health care, and design, manufacturing and marketing. The advantages to using virtual reality include lower product design and manufacturing costs: Fewer physical prototypes are needed, and flaws in both the design and the manufacturing process become apparent while examining the product and the assembly line in a virtual environment. Physical objects and abstract data can both be better understood when viewed from different angles and manipulated in a virtual setting. Virtual-reality assisted training can be more comprehensive, less expensive and safer.
Within government, virtual reality will be used predominantly for design applications in the near future, Fenn says, starting with costly items such as ships and then "moving into smaller-scale design" as equipment prices drop. The military already relies on virtual reality for some of its training and simulation needs. For example, Air Force pilots flying over Bosnia during last year's Operation Deliberate Force rehearsed their missions on a simulation system called PowerScene. Relying on satellite imagery and terrain elevation data, PowerScene displayed terrain and intended targets and allowed pilots to determine optimal flight strategies.
NASA, which uses remote vehicles for science and exploration, has been at the forefront of virtual reality development. When a vehicle lands on another planet, "we need to be able to visualize that environment so we can drive the vehicle around remotely," NASA's Rasmussen says. Scientists need to receive enough information about the environment to do their work "as if they're there," he says.
"Virtual reality is recognized by the brain as an experience," Rasmussen says, making it an "extremely powerful" way for the scientists to understand these distant environments. NASA hopes to deploy the technology on interplanetary missions soon after the turn of the millennium. "I feel we're in the fine-tuning stages," Rasmussen says.
Other agencies have also begun to use virtual reality. The Transportation Department, for example, is investing in a sophisticated driving simulator to better understand human factors involved in traffic accidents so it can better prevent them.
Future Outlook
Within the next few years, the availability of better, yet less expensive virtual reality graphics and head-mounted displays will broaden the technology's appeal, according to Gartner's Fenn. Work also has begun on developing virtual reality applications that accommodate multiple simultaneous users, which will prove useful to geographically scattered colleagues.
Unfortunately, some virtual reality users have reported unwelcome physical side effects, such as migraine headaches, after using high-performance simulators, and because the technology is relatively new, its longer-term effects remain unknown. Even if it is proven to be safe, virtual reality technology may not be right for every situation. "You have to look carefully at the application and ask if in ideal circumstances virtual reality would allow you to do a better job," advises Latta of 4th Wave. If the answer is yes, and if the required level of technology is available, there is also the question of how difficult the technology will be to implement. "It's not a plug-and-play technology yet," says NASA's Rasmussen.
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