Virtual Reality

Virtual reality is a product of the evolution of the computer from an instrument that merely received input from a user to a machine that can adapt to the user's cues to create an almost lifelike experience.

The term virtual reality was coined in 1989 by Jaron Lanier. Others have described the concept as "artificial reality," "cyberspace," and "virtual worlds."

Virtual reality combines state-of-the-art imaging with computer technology to allow users to experience a three-dimensional simulated environment. It is this environment that was called cyberspace in a novel by Canadian science-fiction writer William Gibson.

Cyberspace is interactive. In other words, the user can alter the appearance of the image or the nature of the scene. This interactive medium incorporates powerful computers with video displays, sensors, electronic headsets, and gloves. With these tools, users can both see and manipulate a phantom environment that appears real. Virtual reality tools under development include a whole body suit, which, like diving into water, would totally immerse the user in a virtual world. Although virtual reality has been popularized as a new form of entertainment, it has applications in business, industry, and medicine.

The reality engine

The reality engine employs both computer hardware and software to create the virtual world. Reality engines are based largely on the same components that make up a personal computer (PC), although much more computing power is required for the reality engine than what is available in a standard PC.

One reason for the increased computing power is the complexity of the hardware and software necessary to create a world that appears real. The images created by the computer and software are extremely complex, compared to the relatively simple line-based graphics associated with computer games. Virtual reality images are made with thousands of dots called pixels (or picture elements). The more pixels per given amount of area, the higher the quality of the image. Hence, an image will be more realistic. Creating realistic images that can be manipulated is known as "realization." These images can be either opaque, in which all the viewer sees is the virtual world, or see-through, in which the virtual image is projected or superimposed onto the outer world.

The reality engine is also involved in bringing sound to the virtual world. Sound enriches the virtual world. For example, in a flight simulator, the experience of soaring through the air in a simulated cockpit is more realistic if the user hears the roar of the engines. Sound also enhances participation in the virtual world by providing the user with audio cues. For example, the user may be directed to look for another virtual airplane flying overhead.

To incorporate the total experience provided by the sight and sound cues, the reality engine can use what is known as haptic enhancement. Haptic enhancement utilizes the participant's other senses of touch and pressure in the virtual world. Haptic enhancement is a complex process, and the hardware and software that are required increase the cost of the system tremendously. To date haptic enhancement is used mainly military and research applications.

Headsets

Head-mounted display (HMD) units use a small screen or a pair of screens (one for each eye) that are worn in a helmet or a pair of glasses. The HMD allows viewers to look at an image from various angles or change their field of view by simply moving their heads. In contrast, a movie is a passive experience, where the view of the audience is controlled by the position of the camera that recorded the scene.

HMD units usually employ cathode ray tube (CRT) or liquid crystal display (LCD) technology. The optical systems in CRTs reflect an image onto the viewer's eye, creating an image of very clear and realistic image. CRT images can be semi-reflective. This means that the user can experience the virtual world while still being able to see the outside world. This permits the user to operate another machine or device while viewing the virtual world.

LCD technology has lagged behind CRT in picture quality. LCD monitors display two slightly different images to each eye. The brain processes and merges the images into a single three-dimensional view. However LCD systems have the advantages of being slimmer, lighter, and less expensive than CRT systems. Thus, LCD is better suited to home entertainment. As the A virtual reality system. Photograph by Thomas Ernstein. Bilderberg/Stock Market. Reproduced by permission. image quality improves, LCDs will find a lucrative niche in the home entertainment market.

Audio units

Sound effects in virtual reality rely on a prerecorded sound set. This aspect of the virtual reality experience is less prone to alteration.

The audio portion of virtual reality is transmitted through small speakers placed over each ear. Audio cues may include voices, singing, the sound of bubbling water, thud-like noises of colliding objects—in short, any sound that can be recorded.

While the sounds themselves cannot be changed from a recording, the presentation of the sounds to the user can be changed. Three-dimensional (omnidirectional) sound further enhances the virtual reality experience. Sound that seems to come from above, below, or either side provides audio cues that mimic how sounds are heard in the real world (e.g., footsteps approaching or a plane flying overhead). Three-dimensional sound is achieved through the use of complex filtering devices. This technology must take into account the delay in the detection of sound by the ear that is furthest away from the source of the sound (interaural time difference) and the tendency of one ear to hear a sound more loudly than the other ear (interaural amplitude difference).

The most complex human hearing dynamic is called head-related transfer functions (HRTF). HRTF accounts for how the eardrum and inner ear process sound waves. Factors that are influential in HRTF include the various frequencies at which the sound waves travel, and how waves are absorbed and reflected by other objects. HRTF audio processing enables the listener to locate a sound source and to focus in on a specific sound out of a multitude of sounds. (i.e., the sound of their name called out in the midst of a noisy party).

Gloves

A popular image of a virtual reality experience shows the user wearing gloves. The gloves allow the user to interact with the virtual world. For example, the user may pick up a virtual block, and, by turning their gloved hands, turn the block over and set it on a virtual table.

Virtual reality gloves are wired with thin fiber-optic cables, or have light-emitting diodes positioned at critical points over the glove's surface. The optics detects the amount of light passing through the cable in relation to the movement of the hand or joint. The computer then analyzes the corresponding information and projects this moving hand into the virtual reality. Magnetic tracking systems are also used to determine where the hand is in space in relation to the virtual scene.

Some gloves use haptic enhancement to provide a sense of touch and feel. In haptic enhancement, the reality engine relays the various sensations of force, heat, and texture that are experienced by the user to the computer software. The software can use the information to determine an outcome of the user's actions, and relay the outcomes back to the user. For example, if the user closes a hand on a virtual squeeze toy, the software will alter the virtual image to show the toy becoming compressed. To achieve this two-way communication, virtual reality gloves may use either air pressure (such as strategically placed, inflated air pockets in the glove) or vibrating transducers placed next to the skin (such as a voice coil from a stereo speaker or alloys, which change shape through the conduction of electrical currents) to simulate tactile experience.

Tools under development

Many other virtual reality tools are in the phases of research and development. Remote control robotic or manipulation devices are being tested for industry and medicine. Already, surgery has been done by a physician located hundreds of miles away from the patient, by means of robotics and virtual imaging.

Special wands with sensors, joysticks, and finger sensors such as picks and rings will eventually be as common to virtual reality technology as microwaves are to cooking. The technology to control the virtual world through voice commands is also rapidly advancing.

Perhaps the most impressive technology under development is the whole body suit. These suits would function similarly to the gloves, creating a virtual body that could take a stroll through a virtual world and feel a virtual windstorm.