virtual reality

virtual reality (VR), the use of computer modeling and simulation that enables a person to interact with an artificial three-dimensional (3-D) visual or other sensory environment. VR applications immerse the user in a computer-generated environment that simulates reality through the use of interactive devices, which send and receive information and are worn as goggles, headsets, gloves, or body suits. In a typical VR format, a user wearing a helmet with a stereoscopic screen views animated images of a simulated environment. The illusion of “being there” (telepresence) is effected by motion sensors that pick up the user’s movements and adjust the view on the screen accordingly, usually in real time (the instant the user’s movement takes place). Thus, a user can tour a simulated suite of rooms, experiencing changing viewpoints and perspectives that are convincingly related to his own head turnings and steps. Wearing data gloves equipped with force-feedback devices that provide the sensation of touch, the user can even pick up and manipulate objects that he sees in the virtual environment.

The term virtual reality was coined in 1987 by Jaron Lanier, whose research and engineering contributed a number of products to the nascent VR industry. A common thread linking early VR research and technology development in the United States was the role of the federal government, particularly the Department of Defense, the National Science Foundation, and the National Aeronautics and Space Administration (NASA). Projects funded by these agencies and pursued at university-based research laboratories yielded an extensive pool of talented personnel in fields such as computer graphics, simulation, and networked environments and established links between academic, military, and commercial work. The history of this technological development, and the social context in which it took place, is the subject of this article.

Early work

Artists, performers, and entertainers have always been interested in techniques for creating imaginative worlds, setting narratives in fictional spaces, and deceiving the senses. Numerous precedents for the suspension of disbelief in an artificial world in artistic and entertainment media preceded virtual reality. Illusionary spaces created by paintings or views have been constructed for residences and public spaces since antiquity, culminating in the monumental panoramas of the 18th and 19th centuries. Panoramas blurred the visual boundaries between the two-dimensional images displaying the main scenes and the three-dimensional spaces from which these were viewed, creating an illusion of immersion in the events depicted. This image tradition stimulated the creation of a series of media—from futuristic theatre designs, stereopticons, and 3-D movies to IMAX movie theatres—over the course of the 20th century to achieve similar effects. For example, the Cinerama widescreen film format, originally called Vitarama when invented for the 1939 New York World’s Fair by Fred Waller and Ralph Walker, originated in Waller’s studies of vision and depth perception. Waller’s work led him to focus on the importance of peripheral vision for immersion in an artificial environment, and his goal was to devise a projection technology that could duplicate the entire human field of vision. The Vitarama process used multiple cameras and projectors and an arc-shaped screen to create the illusion of immersion in the space perceived by a viewer. Though Vitarama was not a commercial hit until the mid-1950s (as Cinerama), the Army Air Corps successfully used the system during World War II for anti-aircraft training under the name Waller Flexible Gunnery Trainer—an example of the link between entertainment technology and military simulation that would later advance the development of virtual reality.

Sensory stimulation was a promising method for creating virtual environments before the use of computers. After the release of a promotional film called This Is Cinerama (1952), the cinematographer Morton Heilig became fascinated with Cinerama and 3-D movies. Like Waller, he studied human sensory signals and illusions, hoping to realize a “cinema of the future.” By late 1960, Heilig had built an individual console with a variety of inputs—stereoscopic images, motion chair, audio, temperature changes, odours, and blown air—that he patented in 1962 as the Sensorama Simulator, designed to “stimulate the senses of an individual to simulate an actual experience realistically.” During the work on Sensorama, he also designed the Telesphere Mask, a head-mounted “stereoscopic 3-D TV display” that he patented in 1960. Although Heilig was unsuccessful in his efforts to market Sensorama, in the mid-1960s he extended the idea to a multiviewer theatre concept patented as the Experience Theater and a similar system called Thrillerama for the Walt Disney Company.

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The seeds for virtual reality were planted in several computing fields during the 1950s and ’60s, especially in 3-D interactive computer graphics and vehicle/flight simulation. Beginning in the late 1940s, Project Whirlwind, funded by the U.S. Navy, and its successor project, the SAGE (Semi-Automated Ground Environment) early-warning radar system, funded by the U.S. Air Force, first utilized cathode-ray tube (CRT) displays and input devices such as light pens (originally called “light guns”). By the time the SAGE system became operational in 1957, air force operators were routinely using these devices to display aircraft positions and manipulate related data.

During the 1950s, the popular cultural image of the computer was that of a calculating machine, an automated electronic brain capable of manipulating data at previously unimaginable speeds. The advent of more affordable second-generation (transistor) and third-generation (integrated circuit) computers emancipated the machines from this narrow view, and in doing so it shifted attention to ways in which computing could augment human potential rather than simply substituting for it in specialized domains conducive to number crunching. In 1960 Joseph Licklider, a professor at the Massachusetts Institute of Technology (MIT) specializing in psychoacoustics, posited a “man-computer symbiosis” and applied psychological principles to human-computer interactions and interfaces. He argued that a partnership between computers and the human brain would surpass the capabilities of either alone. As founding director of the new Information Processing Techniques Office (IPTO) of the Defense Advanced Research Projects Agency (DARPA), Licklider was able to fund and encourage projects that aligned with his vision of human-computer interaction while also serving priorities for military systems, such as data visualization and command-and-control systems.

Another pioneer was electrical engineer and computer scientist Ivan Sutherland, who began his work in computer graphics at MIT’s Lincoln Laboratory (where Whirlwind and SAGE had been developed). In 1963 Sutherland completed Sketchpad, a system for drawing interactively on a CRT display with a light pen and control board. Sutherland paid careful attention to the structure of data representation, which made his system useful for the interactive manipulation of images. In 1964 he was put in charge of IPTO, and from 1968 to 1976 he led the computer graphics program at the University of Utah, one of DARPA’s premier research centres. In 1965 Sutherland outlined the characteristics of what he called the “ultimate display” and speculated on how computer imagery could construct plausible and richly articulated virtual worlds. His notion of such a world began with visual representation and sensory input, but it did not end there; he also called for multiple modes of sensory input. DARPA sponsored work during the 1960s on output and input devices aligned with this vision, such as the Sketchpad III system by Timothy Johnson, which presented 3-D views of objects; Larry Roberts’s Lincoln Wand, a system for drawing in three dimensions; and Douglas Engelbart’s invention of a new input device, the computer mouse.

Within a few years, Sutherland contributed the technological artifact most often identified with virtual reality, the head-mounted 3-D computer display. In 1967 Bell Helicopter (now part of Textron Inc.) carried out tests in which a helicopter pilot wore a head-mounted display (HMD) that showed video from a servo-controlled infrared camera mounted beneath the helicopter. The camera moved with the pilot’s head, both augmenting his night vision and providing a level of immersion sufficient for the pilot to equate his field of vision with the images from the camera. This kind of system would later be called “augmented reality” because it enhanced a human capacity (vision) in the real world. When Sutherland left DARPA for Harvard University in 1966, he began work on a tethered display for computer images (see photograph). This was an apparatus shaped to fit over the head, with goggles that displayed computer-generated graphical output. Because the display was too heavy to be borne comfortably, it was held in place by a suspension system. Two small CRT displays were mounted in the device, near the wearer’s ears, and mirrors reflected the images to his eyes, creating a stereo 3-D visual environment that could be viewed comfortably at a short distance. The HMD also tracked where the wearer was looking so that correct images would be generated for his field of vision. The viewer’s immersion in the displayed virtual space was intensified by the visual isolation of the HMD, yet other senses were not isolated to the same degree and the wearer could continue to walk around.