Virtual reality

Etymology and terminology

In 1938, Antonin Artaud described the illusory nature of characters and objects in the theatre as "la réalité virtuelle" in a collection of essays, Le Théâtre et son double. The English translation of this book, published in 1958 as The Theater and its Double, is the earliest published use of the term "virtual reality". The term "artificial reality", coined by Myron Krueger, has been in use since the 1970s. The term "virtual reality" was used in The Judas Mandala, a 1982 science fiction novel by Damien Broderick. "Virtual" has had the meaning "being something in essence or effect, though not actually or in fact" since the mid-1400s, "...probably via sense of "capable of producing a certain effect" (early 1400s)". The term "virtual" has been used in the computer sense of "not physically existing but made to appear by software" since 1959.

A dictionary definition for "cyberspace" states that this word is a synonym for "virtual reality", but the two terms are fundamentally different (something that is "virtual" does not necessarily need to rely on a network, for instance).

Virtual reality shares some elements with "augmented reality" (or AR). AR is a type of virtual reality technology that blends what the user sees in their real surroundings with digital content generated by computer software. The additional software-generated images with the virtual scene typically enhance way the real surroundings look in some way. Some AR systems use a camera to capture the user's surroundings or some type of display screen which the user looks at (e.g., Microsoft's HoloLens, Magic Leap).

Technology

The Virtual Reality Modelling Language VRML, first introduced in 1994, was intended for the development of "virtual worlds" without dependency on headsets. The Web3D consortium was subsequently founded in 1997 for the development of industry standards for web-based 3D graphics. The consortium subsequently developed X3D from the VRML framework as an archival, open-source standard for web-based distribution of VR content.

All modern VR displays are based on technology developed for smartphones including: gyroscopes and motion sensors for tracking head, hand, and body positions; small HD screens for stereoscopic displays; and small, lightweight and fast processors. These components led to relative affordability for independent VR developers, and lead to the 2012 Oculus Rift kickstarter offering the first independently developed VR headset.

Independent production of VR images and video has increased by the development of omnidirectional cameras, also known as 360-degree cameras or VR cameras, that have the ability to record in all directions, although at low-resolutions or in highly compressed formats for online streaming. In contrast, photogrammetry is increasingly used to combine several high-resolution photographs for the creation of detailed 3D objects and environments in VR applications.

Before the 1950s

The exact origins of virtual reality are disputed, partly because of how difficult it has been to formulate a definition for the concept of an alternative existence. Elements of virtual reality have surfaced as early as the 1860s with French playwright Antonin Artaud who used avant-garde work to blur illusion and reality to be one and the same. He argued that a theatre audience should suspend their disbelief and consider the performance to be reality. The first references to the more modern concept of virtual reality came from science fiction. Stanley G. Weinbaum's 1935 short story "Pygmalion's Spectacles" describes a goggle-based virtual reality system with holographic recording of fictional experiences, including smell and touch.

1950–1970

Morton Heilig wrote in the 1950s of an "Experience Theatre" that could encompass all the senses in an effective manner, thus drawing the viewer into the onscreen activity. He built a prototype of his vision dubbed the Sensorama in 1962, along with five short films to be displayed in it while engaging multiple senses (sight, sound, smell, and touch). Predating digital computing, the Sensorama was a mechanical device. Heilig also developed what he referred to as the "Telesphere Mask" (patented in 1960). The patent application described the device as "a telescopic television apparatus for individual use...The spectator is given a complete sensation of reality, i.e. moving three dimensional images which may be in colour, with 100% peripheral vision, binaural sound, scents and air breezes".

Around the same time, Douglas Engelbart used computer screens both as input and output devices. In 1968, Ivan Sutherland, with the help of his student Bob Sproull, created what was widely considered to be the first virtual reality and augmented reality (AR) head-mounted display (HMD) system. It was primitive both in terms of user interface and realism, and the HMD to be worn by the user was so heavy that it had to be suspended from the ceiling. The graphics comprising the virtual environment were simple wire-frame model rooms. The formidable appearance of the device inspired its name, The Sword of Damocles.

1970–1990

Also notable among the earlier hypermedia and virtual reality systems was the Aspen Movie Map, which was created at MIT in 1978. The program was a crude virtual simulation of Aspen, Colorado in which users could wander the streets in one of the three modes: summer, winter, and polygons. The first two were based on photographs—the researchers actually photographed every possible movement through the city's street grid in both seasons—and the third was a basic 3-D model of the city. Atari founded a research lab for virtual reality in 1982, but the lab was closed after two years due to Atari Shock (North American video game crash of 1983). However, its hired employees, such as Tom Zimmerman, Scott Fisher, Jaron Lanier and Brenda Laurel, kept their research and development on VR-related technologies. By the 1980s the term "virtual reality" was popularized by Jaron Lanier, one of the modern pioneers of the field. Lanier had founded the company VPL Research in 1985. VPL Research has developed several VR devices like the Data Glove, the Eye Phone, and the Audio Sphere. VPL licensed the Data Glove technology to Mattel, which used it to make an accessory known as the Power Glove. While the Power Glove was hard to use and not popular, at US$75, it was an early affordable VR device.

The VR industry mainly provided VR devices for medical, flight simulation, automobile industry design, and military training purposes from 1970 to 1990.

1990–2000

In 1991, Carolina Cruz-Neira, Daniel J. Sandin and Thomas A. DeFanti from the Electronic Visualization Laboratory created the first cubic immersive room, The Cave. Developed as Cruz-Neira's PhD thesis, it involved a multi-projected environment, similar to the holodeck, allowing people to see their own bodies in relation to others in the room.

The 1990s saw the first widespread commercial releases of consumer headsets. In 1991, Sega announced the Sega VR headset for arcade games and the Mega Drive console. It used LCD screens in the visor, stereo headphones, and inertial sensors that allowed the system to track and react to the movements of the user's head. In the same year, Virtuality launched and went on to become the first mass-produced, networked, multiplayer VR entertainment system. It was released in many countries, including a dedicated VR arcade at Embarcadero Center in San Francisco. Costing up to $73,000 per multi-pod Virtuality system, they featured headsets and exoskeleton gloves that gave one of the first "immersive" VR experiences. Antonio Medina, a MIT graduate and NASA scientist, designed a virtual reality system to "drive" Mars rovers from Earth in apparent real time despite the substantial delay of Mars-Earth-Mars signals.

In 1991, Computer Gaming World predicted "Affordable VR by 1994". By 1994, Sega released the Sega VR-1 motion simulator arcade attraction, in SegaWorld amusement arcades. It was able to track head movement and featured 3D polygon graphics in stereoscopic 3D, powered by the Sega Model 1 arcade system board. Also in 1994 Apple released QuickTime VR, which, despite using the term "VR", was unable to represent virtual reality, and instead displayed 360 photographic panoramas.

A non-VR system called the Virtual Boy was created by Nintendo and was released in Japan on July 21, 1995 and in North America on August 15, 1995. Also in 1995, a group in Seattle created public demonstrations of a "CAVE-like" 270 degree immersive projection room called the Virtual Environment Theater, produced by entrepreneurs Chet Dagit and Bob Jacobson. The same system was shown in 1996 in tradeshow exhibits sponsored by Netscape Communications. Forte released the VFX1, a PC-powered virtual reality headset in 1995, which was supported by games including Descent, Star Wars: Dark Forces, System Shock and Quake.

In 1999, entrepreneur Philip Rosedale formed Linden Lab with an initial focus on the development of VR hardware. In its earliest form, the company struggled to produce a commercial version of "The Rig", which was realized in prototype form as a clunky steel contraption with several computer monitors that users could wear on their shoulders. The concept was later adapted into the personal computer-based, 3D virtual world Second Life.

2000–2015

In 2001, SAS3 or SAS Cube became the first PC based cubic room, developed by Z-A Production (Maurice Benayoun, David Nahon), Barco, Clarté, installed in Laval France in April 2001. The SAS library gave birth to Virtools VRPack. By 2007, Google introduced Street View, a service that shows panoramic views of an increasing number of worldwide positions such as roads, indoor buildings and rural areas. It also features a stereoscopic 3D mode, introduced in 2010.

In 2010, Palmer Luckey designed the first prototype of the Oculus Rift. This prototype, built on a shell of another virtual reality headset, was only capable of rotational tracking. However, it boasted a 90-degree field of vision that was previously unseen in the consumer market at the time. This initial design would later serve as a basis from which the later designs came.

In 2013, Valve discovered and freely shared the breakthrough of low-persistence displays which make lag-free and smear-free display of VR content possible. This was adopted by Oculus and was used in all their future headsets.

In early 2014, Valve showed off their SteamSight prototype, the precursor to both consumer headsets released in 2016. It shared major features with the consumer headsets including separate 1K displays per eye, low persistence, positional tracking over a large area, and fresnel lenses.

On March 25, 2014, Facebook purchased Oculus VR for $2 billion. This purchase occurred before any of the devices ordered through Oculus' 2012 Kickstarter had shipped. In that same month, Sony announced Project Morpheus (its code name for PlayStation VR), a virtual reality headset for the PlayStation 4 video game console. Google announces Cardboard, a do-it-yourself stereoscopic viewer for smartphones. The user places their smartphone in the cardboard holder, which they wear on their head. In 2015, the Kickstarter campaign for Gloveone, a pair of gloves providing motion tracking and haptic feedback, was successfully funded, with over $150,000 in contributions.

In February–March 2015, HTC and Valve Corporation announced the virtual reality headset HTC Vive and controllers. The set included tracking technology called Lighthouse, which utilized wall-mounted "base stations" for positional tracking using infrared light.

2015–present

By 2016 there were at least 230 companies developing VR-related products. Facebook had 400 employees focused on VR development; Google, Apple, Amazon, Microsoft, Sony and Samsung all had dedicated AR and VR groups. Dynamic binaural audio was common to most headsets released that year. However, haptic interfaces were not well developed, and most hardware packages incorporated button-operated handsets for touch-based interactivity. Visually, displays were still of a low-enough resolution and frame-rate that images were still identifiable as virtual. On April 5, 2016, HTC shipped its first units of the HTC VIVE SteamVR headset. This marked the first major commercial release of sensor-based tracking, allowing for free movement of users within a defined space.

In early 2017, a patent filed by Sony showed they were developing a similar location tracking technology to the VIVE for PlayStation VR, with the potential for the development of a wireless headset.

Video games

Several virtual reality head mounted displays (HMD) were released for gaming during the early-mid 1990s. These included the Virtual Boy developed by Nintendo, the iGlasses developed by Virtual I-O, the Cybermaxx developed by Victormaxx and the VFX1 Headgear developed by Forte Technologies. Other modern examples of narrow VR for gaming include the Wii Remote, the Kinect, and the PlayStation Move/PlayStation Eye, all of which track and send motion input of the players to the game console somewhat accurately.

Commercial tethered headsets released for VR gaming include the Oculus Rift and the HTC Vive. Systems in development include Sony's PlayStation VR, requiring a PlayStation instead of a PC to run; the StarVR; FOVE; and the Magic Leap.

Following the widespread release of commercial VR headsets in the mid-2010s, several VR-specific and VR versions of popular videogames have been released. Guild Software's Vendetta Online was widely reported as the first MMORPG to support the Oculus Rift, making it potentially the first persistent online world with native support for a consumer virtual reality headset. Since 2013, there have been several virtual reality devices that seek to enter the market to complement Oculus Rift to enhance the game experience. One, Virtuix Omni, is based on the ability to move in a three dimensional environment through an omnidirectional treadmill. On April 27, 2016, Mojang announced that the popular children's video game Minecraft was playable on the Gear VR. A separate version was released to the Oculus Store for use with the Gear VR, similar to the Pocket Edition of Minecraft.

Some companies are adapting VR for fitness by using gamification concepts to encourage exercise.

Cinema and entertainment

Films produced for VR permit the audience to view a 360 degree environment in every scene. Production companies, such as Fox Searchlight Pictures and Skybound, utilize VR cameras to produce films and series that are interactive in VR. Pornographic studios such as Naughty America, BaDoinkVR and Kink have applied VR into their products since late 2015 or early 2016. The clips and videos are shot from an angle that resembles POV-style porn.

In September 2016, two announcements were made for broadcast of sporting events in VR. Agon announced that the upcoming World Chess Championship match between Magnus Carlsen and Sergey Karjakin, scheduled for that November, would be "the first in any sport to be broadcast in 360-degree virtual reality." This title was taken by Fox Sports' Fox Sports VR, a series of virtual reality broadcasts consisting mainly of Fox College Football broadcasts. The telecasts (which use roughly 180 degrees of rotation) were made available through smartphone apps and head-mounted displays, through a TV Everywhere paywall. The first VR telecast, which featured Oklahoma hosting Ohio State, took place September 17.

Since 2015, virtual reality has been installed onto a number of roller coasters and theme parks, including Galactica at Alton Towers, The New Revolution at Six Flags Magic Mountain and Alpenexpress at Europapark, amongst others. The Void is a virtual reality theme park in Pleasant Grove, Utah that has attractions where, by using virtual reality, AR and customized mechanical rooms, an illusion of tangible reality is created by the use of multiple senses.

Healthcare and clinical therapies

According to a recent report from Goldman Sachs, healthcare could be one of the next markets that VR/AR disrupts. Already, VR devices are being used in clinical therapy, and the results are significant.

Anxiety disorder treatment

Virtual Reality Exposure Therapy (VRET) is a form of exposure therapy for treating anxiety disorders such as post traumatic stress disorder (PTSD) and phobias. Studies have indicated that when VRET is combined with other forms of behavioral therapy, patients experience a reduction of symptoms. In some cases, patients no longer meet the DSM-V criteria for PTSD after a series of treatments with VRET.

Pain management

Burn victims experience acute pain from their injuries especially when wound dressings are changed. Opioids are commonly used to reduce pain, but immersive VR is emerging as an alternative, drug-free method for pain management. Researchers theorize that immersive VR helps with pain reduction by distracting the mind and flooding sensories with a positive experience.

Education and training

VR is used to provide learners with a virtual environment where they can develop their skills without the real-world consequences of failing.

Military uses

Thomas A. Furness III was one of the first to develop the use of VR for military training when, in 1982, he presented the Air Force with a working model of his virtual flight simulator the Visually Coupled Airborne Systems Simulator (VCASS). The second phase of his project, which he called the "Super Cockpit", was even more advanced, with high resolution graphics (for the time) and a responsive display. Furness III is often credited as a pioneer in virtual reality for this research. The Ministry of Defense in the United Kingdom has been using VR in military training since the 1980s. The United States military announced the Dismounted Soldier Training System in 2012. It was cited as the first fully immersive military VR training system.

Space training

NASA has used VR technology for twenty years. Most notable is their use of immersive VR to train astronauts while they are still on Earth. Such applications of VR simulations include exposure to zero-gravity work environments and training on how to spacewalk. Astronauts can even simulate what it is like to work with tools in space while using low cost 3D printed mock up tools.

Flight and vehicular applications

Flight simulators are a form of VR pilot training. They can range from a fully enclosed module to a series of computer monitors providing the pilot's point of view. By the same token, virtual driving simulations are used to train tank drivers on the basics before allowing them to operate the real vehicle. Similar principals are applied in truck driving simulators for specialized vehicles such as firetrucks. As these drivers often have less opportunity for real-world experience, VR training provides additional training time.

Medical training

VR technology has many useful applications in the medical field. Simulated surgeries allow surgeons to practice their technical skills without any risk to patients. Numerous studies have shown that physicians who receive surgical training via VR simulations improve dexterity and performance in the operating room significantly more than control groups. Through VR, medical students and novice surgeons have the ability to view and experience complex surgeries without stepping into the operating room. On April 14, 2016, Shafi Ahmed was the first surgeon to broadcast an operation in virtual reality; viewers followed the surgery in real time from the surgeon's perspective. The VR technology allowed viewers to explore the full range of activities in the operating room as it was streamed by a 4K 360fly camera.

Fine arts

David Em was the first fine artist to create navigable virtual worlds in the 1970s. His early work was done on mainframes at Information International, Inc., Jet Propulsion Laboratory, and California Institute of Technology. Jeffrey Shaw explored the potential of VR in fine arts with early works like Legible City (1989), Virtual Museum (1991), and Golden Calf (1994).

Virtopia was the first VR Artwork to be premièred at a film festival. Created by artist/researcher Jacquelyn Ford Morie with researcher Mike Goslin, it debuted at the 1992 Florida Film Festival. Subsequent screenings of a more developed version of the project were at the 1993 Florida Film Festival and at SIGGRAPH 1994's emerging tech venue, The Edge. Morrie was one of the first artists to focus on emotional content in VR experiences.

Canadian artist Char Davies created immersive VR art pieces Osmose (1995) and Ephémère (1998). Maurice Benayoun's work introduced metaphorical, philosophical or political content, combining VR, network, generation and intelligent agents, in works like Is God Flat? (1994), "Is the Devil Curved?" (1995), The Tunnel under the Atlantic (1995), and World Skin, a Photo Safari in the Land of War (1997). Other pioneering artists working in VR have include Knowbotic Research, Rebecca Allen and Perry Hoberman. In 2016, the first project in Poland called The Abakanowicz Art Room was realized – it was documentation of the art office professor Magdalena Abakanowicz made by Jarosław Pijarowski and Paweł Komorowski.

Some museums have begun making some of their content virtual reality accessible including the British Museum and the Guggenheim.

Engineering

The use of 3D computer-aided design (CAD) data was limited by 2D monitors and paper printouts until the mid-to-late 1990s, when video projectors, 3D tracking, and computer technology enabled a renaissance in the use 3D CAD data in virtual reality environments. With the use of active shutter glasses and multi-surface projection units immersive engineering was made possible by companies like VRcom and IC.IDO. Virtual reality has been used in automotive, aerospace, and ground transportation original equipment manufacturers (OEMs) in their product engineering and manufacturing engineering . Virtual reality adds more dimensions to virtual prototyping, product building, assembly, service, performance use-cases. This enables engineers from different disciplines to view their design as its final product. Engineers can view the virtual bridge, building or other structure from any angle. As well, some computer models allow engineers to test their structure's resistance to winds, weight, and other elements. Immersive VR engineering systems enable engineers to see virtual prototypes prior to the availability of any physical prototypes.

Virtual reality in occupational safety and health

VR simulates real workplaces for occupational safety and health purposes. Information and projection technology are used to produce a virtual, three-dimensional, dynamic work environment. Within work scenarios for example some parts of a machine move of their own accord while others can be moved by human operators. Perspective, angle of view, and acoustic and haptic properties change according to where the person is standing and how he or she moves relative to the environment. VR technology allows human information processing close to real life situations. VR enables all phases of a product life cycle, from design, through use, up to disposal, to be simulated, analysed and optimised. VR can be used for OSH purposes to:

Heritage and archaeology

The first use of a VR presentation in a heritage application was in 1994, when a museum visitor interpretation provided an interactive "walk-through" of a 3D reconstruction of Dudley Castle in England as it was in 1550. This consisted of a computer controlled laserdisc-based system designed by British-based engineer Colin Johnson. The system was featured in a conference held by the British Museum in November 1994, and in the subsequent technical paper, Imaging the Past – Electronic Imaging and Computer Graphics in Museums and Archaeology. Virtual reality enables heritage sites to be recreated extremely accurately, so that the recreations can be published in various media. The original sites are often inaccessible to the public or, due to the poor state of their preservation, hard to picture. This technology can be used to develop virtual replicas of caves, natural environment, old towns, monuments, sculptures and archaeological elements.

Architectural and urban design

One of the first recorded uses of virtual reality in architecture was in the late 1980s when the University of North Carolina modeled its Sitterman Hall, home of its computer science department, in a virtual environment.

By 2010, VR programs were developed for urban regeneration, planning and transportation projects.

Music and concerts

VR has the possibility of changing how we view live music by allowing the audience to be right up front their band or to attend virtual concerts like Coachella. Virtual reality can also transform music videos by making them more intense and powerful. Music visualization also has the potential to be changed by VR with multiple apps being created for the Oculus and the HTC Vive although some people dubious as to how popular these will be. Virtual reality is also used in visual music applications.

On May 3, 2016, Norwegian pop band a-ha gave a multimedia performance in collaboration with Void, a Norwegian computational design studio. The stereoscopic VR-experience was made available for Android users directly through a YouTube app and also made available for iPhone users and other platforms.

Marketing

Virtual reality presents a unique opportunity for advertisers to reach a completely immersed audience. Companies such as Paramount Pictures, Coca-Cola, McDonald's and Disney have applied VR into marketing campaigns. Non-profit organizations such as Amnesty International, UNICEF, and World Wide Fund for Nature (WWF) have used virtual reality to bring potential supporters closer to their work, effectively bringing distant social, political and environmental issues and projects to members of the public in immersive ways not possible with traditional media. Panoramic 360 views of conflict in Syria and face to face encounters with CGI tigers in Nepal have been used in experiential activations and shared online for educational and fundraising purposes.

Lowe's, IKEA, Wayfair and other retailers have developed systems that allow their products to be seen in virtual reality, to give consumers a better idea of how the product will fit into their home, or to allow the consumer to get a better look at the product from home. Consumers looking at digital photos of the products can "turn" the product around virtually, and see it from the side or the back.

Several companies develop software or services that allow architectural design firms and real estate clients to tour virtual models of proposed building designs. During the design process, architects can use VR to experience the designs they are working on before they are built. Seeing a design in VR can give architect a correct sense of scale and proportion. VR models can replace physical miniatures to demonstrate a design to clients or the public. Developers and owners can create VR model of built spaces that allow potential buyers or tenants to tour a space in VR, even if real-life circumstances make a physical tour unfeasible.

In July 2015, OnePlus became the first company to launch a product using virtual reality. This was for their second flagship device the OnePlus 2, first viewable using OnePlus Cardboard, based on Google Cardboard platform. It was accessed through an app released on Google Play Store, then on YouTube.

In fiction and popular culture

There have been many novels that reference and describe forms of virtual reality. Neal Stephenson's Snow Crash (1992) and Ernest Cline's Ready Player One (2011) are novels that have been influential for VR engineers working in the early 21st century.

In the 1980s and 1990s, Cyberpunks viewed the technology as a potential means for social change. The recreational drug subculture praised virtual reality not only as a new art form, but as an entirely new frontier.

Concerns and challenges

Virtual reality technology faces a number of challenges, including health and safety, privacy and technical issues. Long-term effects of virtual reality on vision and neurological development are unknown; users might become disoriented in a purely virtual environment, causing balance issues; computer latency might affect the simulation, providing a less-than-satisfactory end-user experience; navigating the non-virtual environment (if the user is not confined to a limited area) might prove dangerous without external sensory information. There have been rising concerns that with the advent of virtual reality, some users may experience virtual reality addiction.

Health and safety

There are many health and safety considerations of virtual reality. Most virtual reality systems come with consumer warnings, including: seizures; developmental issues in children; trip-and-fall and collision warnings; discomfort; repetitive stress injury; and interference with medical devices.

A number of unwanted symptoms have been caused by prolonged use of virtual reality, and these may have slowed proliferation of the technology. Virtual reality sickness (also known as cybersickness) occurs when a person's exposure to a virtual environment causes symptoms that are similar to motion sickness symptoms. The most common symptoms are general discomfort, headache, stomach awareness, nausea, vomiting, pallor, sweating, fatigue, drowsiness, disorientation, and apathy. Other symptoms include postural instability and retching. Estimates for susceptibility range from one in every thirty to one in every two people. For women, rates are as high as four in five. Virtual reality sickness is different from motion sickness in that it can be caused by the visually induced perception of self-motion; real self-motion is not needed. It is also different from simulator sickness; non-virtual reality simulator sickness tends to be characterized by oculomotor disturbances, whereas virtual reality sickness tends to be characterized by disorientation. A 2016 publication assessed the effects of exposure to 2D vs 3D dissection videos on nine pathology resident physicians, using self-reported physiologic symptoms. Watching the content in 3D vs 2D did not increase simulator sickness. Although the average simulator sickness questionnaire score did increase with time, statistical analysis does not suggest significance.

In the mid-2010s, greater attention was paid to the effects of VR headsets on vision and the brain. Research at UCLA by neuroscientist Mayank Mehta discovered that in rats exposed to VR environments, the hippocampus did not create a "mental map" of the virtual space as it would for a real world environment.

In 3D stereoscopic headsets, negative effects on the vestibulo-ocular reflex and vergence-accommodation conflicts are of ophthalmic concern. As of 2016, the visual space perception laboratory at UC Berkeley found that vision-based effects of 3D stereoscopic headsets were short-term, but that further research was needed on long-term effects. In 2015 Magic Leap's founder, Rony Abovitz, claimed his digital light field technology carried none of the negative neurological effects of 3D stereoscopic displays; however, no research had been published to support the company's claims.

Privacy

The persistent tracking required by all VR systems makes the technology particularly useful for, and vulnerable to, mass surveillance. The expansion of VR will increase the potential and reduce the costs for information gathering of personal actions, movements and responses.

Conceptual and philosophical concerns

In addition, there are conceptual, and philosophical considerations and implications associated with the use of virtual reality. What the phrase "virtual reality" means or refers to can be ambiguous. Mychilo S. Cline argued in 2005 that through virtual reality techniques will be developed to influence human behavior, interpersonal communication, and cognition. In the book The Metaphysics of Virtual Reality by Michael R. Heim, seven different concepts of virtual reality are identified: simulation, interaction, artificiality, immersion, telepresence, full-body immersion, and network communication. As we spend more and more time in virtual space, there could be a gradual "migration to virtual space", resulting in important changes in economics, worldview, and culture. Philosophical implications of VR are discussed in books, including Philip Zhai's Get Real: A Philosophical Adventure in Virtual Reality (1998) and Digital Sensations: Space, Identity and Embodiment in Virtual Reality (1999), written by Ken Hillis.

Commercial industries

The companies working in the virtual reality sector fall broadly into three categories of involvement: hardware (making headsets and input devices specific to VR), software (producing software for interfacing with the hardware or for delivering content to users) and content creation (producing content, whether interactive or passive storylines, games, and artificial worlds, for consumption and exploration with VR hardware).