CAVE
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CAVE (CAVE Automatic Virtual Environment) is a full room-based projection virtual reality system that projects images onto the walls and floor of a room-sized cube, surrounding one or more viewers with stereoscopic, head-tracked computer graphics.[1][2] The first CAVE was built at the Electronic Visualization Laboratory (EVL) of the University of Illinois Chicago in 1991 and premiered at the SIGGRAPH '92 conference in 1992.[1][3]
The CAVE was designed by Carolina Cruz-Neira, Daniel J. Sandin and Thomas A. DeFanti as a tool for scientific visualization.[1] Instead of moving small screens in front of the eyes, as a head-mounted display does, it keeps large projection screens fixed around the user and recomputes the perspective on every wall from the tracked position of the viewer's head.[1] EVL describes it as "the first widely replicated, projection-based, walk-in, virtual-reality (VR) system in the world".[3] CAVE is a trademark of the University of Illinois Board of Trustees, and the design has been commercialized under license by Mechdyne Corporation.[4]
Name
The name is a recursive acronym, "CAVE Automatic Virtual Environment", and also a reference to "The Simile of the Cave" in Plato's Republic, in which the philosopher discusses inferring reality (ideal forms) from shadows projected on the wall of a cave.[1] The designers noted that "virtual environments" is part of the acronym, but used the initials VR in their papers to match mainstream usage.[1]
History
According to EVL, the CAVE was invented in 1991.[2] The 1993 SIGGRAPH paper states that the system was designed in early 1991 and was implemented and demonstrated to visitors in late 1991.[1] A University of Illinois history of its virtual reality work also dates the invention to 1991 at EVL.[5]
The designers traced the CAVE's motivation to scientific visualization and to the Showcase program at SIGGRAPH '92, an effort chaired by James E. George to let computational scientists present their research to large audiences on high-end workstations connected to large projection screens.[1] EVL built the CAVE as a "Virtual Reality Theater" for that setting.[1] SIGGRAPH '92 was held in Chicago from 26 to 31 July 1992.[6] The CAVE premiered there; Sun Microsystems showed Michael Deering's Virtual Portal, a closet-sized three-wall projection system, at the same conference.[1] At SIGGRAPH '92 and Supercomputing '92, more than a dozen scientists used the CAVE to present work in neuroscience, astrophysics, superconductivity, molecular dynamics, computational fluid dynamics, fractals and medical imaging.[1]
The first journal description, "The CAVE: Audio Visual Experience Automatic Virtual Environment" by Cruz-Neira, Sandin, DeFanti, Robert V. Kenyon and John C. Hart, appeared in Communications of the ACM in June 1992.[7] The detailed design paper, "Surround-Screen Projection-Based Virtual Reality: The Design and Implementation of the CAVE", followed at SIGGRAPH '93.[1] EVL lists Cruz-Neira, Sandin, DeFanti, Dave Pape and Greg Dawe as researchers on the project.[2] By 1993 the CAVE was a research resource for scientists at the University of Illinois at Chicago, the National Center for Supercomputing Applications, Argonne National Laboratory, the University of Chicago, the California Institute of Technology and the University of Minnesota.[1] A sister installation of the original CAVE ran on the Urbana-Champaign campus from 1995 until the Illinois Simulator Lab closed in 2017.[5]
In a 2013 announcement, Mechdyne said its working relationship with EVL began in 1994, when it licensed the original CAVE technology.[4] In June 2001 EVL built the Bright Advanced Technology CAVE (BAT CAVE), which used Christie Digital Systems Mirage 5000 projectors, described by EVL as the first DLP-based active stereoscopic projector, together with near-black screens for higher contrast.[2]
Design
Original system
The CAVE shown at conferences was a 10 ft by 10 ft by 10 ft theater made of three rear-projection wall screens and a down-projected floor screen; EVL's own development system was 7 ft by 7 ft by 7 ft because of ceiling height limits.[1] With the projector optics folded by mirrors, the whole installation needed a 30 ft by 20 ft by 13 ft room, and conference showings required building a light-tight structure of that size on site.[1]
| Component | Implementation |
|---|---|
| Screens | Three rear-projected walls and one down-projected floor[1] |
| Image | Full-color 1280x512 stereo fields at 120 Hz per screen, 2,000 to 4,000 linear pixels across the composite image[1] |
| Stereo | Frame-sequential stereo with Stereographics LCD shutter glasses synchronized by infrared transmitters; 120 fields per second, so the full image updated at 60 Hz[1] |
| Tracking | Head and hand tracked with tethered electromagnetic sensors from Polhemus or Ascension[1] |
| Computing | Four Silicon Graphics high-end workstations (one per screen) plus a fifth for input devices and synchronization, linked by Systran fiber-optic reflective memory[1] |
| Audio | Computer-controlled audio to multiple speakers for sonification[1] |
| Capacity | Up to 12 people could share the space[1] |
A 2013 EVL comparison table lists the 1992 system's stereo resolution as 2.6 megapixels (1280 x 512 x 4), its display cost as $35,000 per stereo megapixel with Electrohome Marquee 8000 projectors, and its total cost as $2 million in 2013 dollars.[8][9]
How it works
The CAVE treats a cube as an approximation of a sphere. Flat walls suit off-the-shelf graphics hardware and projectors, and the imperfections of a built cube fall within the keystone and pincushion adjustments of standard video projectors, so images can be matched at the seams and corners.[1] Rather than the "camera" projection used by head-mounted displays, the CAVE uses a window projection paradigm: each wall is a fixed projection plane, and an off-axis perspective projection is computed for each eye from the viewer's tracked position relative to that wall.[1] The designers did not assume the eyes were level; the tracker sat 5.5 inches above the stereo glasses, centered between the eyes, and an interpupillary distance of 2.75 inches was assumed to derive the position of each eye.[1]
Several practical problems had to be solved. The standard green phosphor in projection tubes persisted too long for frame-sequential stereoscopy, so until Stereographics supplied specially coated tubes, EVL's 1991 experiments used only red, blue and magenta.[1] The walls had to update in exact synchronization, because a single frame of lag made the corners crease; the team used reflective memory shared between the workstations to meet the required 8 ms.[1] The wall screens were a 10 ft by 30 ft plastic sheet stretched over stainless steel cable, leaving a seam of about a pixel, and the screen frame was built from non-magnetic stainless steel because of the electromagnetic tracking.[1] Walls were rear-projected so that people inside cast no shadows, while the floor image was projected from the front top so a user's shadow fell mainly behind them.[1]
With several people inside, only one viewer is tracked and sees correct perspective. The designers had a "guide" control navigation while the tracked "tourist" stood in front, and noted that stereo collapses when one person blocks another's view of an object meant to appear between them.[1]
Tracking errors compared with head-mounted displays
Because the CAVE's projection planes do not move with the head, a head-rotation tracking error about the eye produces no image error, whereas in a head-mounted display or BOOM the same rotational error shifts the entire image.[1] The 1993 paper modeled latency-induced errors at a display rate of 10 frames per second. For a head pan of 90 degrees per second, it calculated that for distant objects the CAVE had 43 times less angular error than an HMD or BOOM and 4 times less than a head-tracked monitor; for a 3 cm positional error with distant objects, however, the HMD and BOOM performed best and the CAVE had 2.5 times their error.[1]
The authors also reported that of about 9,000 people who had used the CAVE, two had complained of nausea. They did not know the reason and suggested the slow-changing scientific content or the system's tolerance of fast head rotation as possible explanations.[1] A 2014 Duke University study with 53 participants compared a desktop system, a head-mounted display and a six-wall fully immersive system in stressful virtual environments; the six-wall system produced the highest sense of presence, and the head-mounted display produced the most simulator sickness.[10]
Limitations
The original designers listed several shortcomings: the CAVE was large and expensive, it was not sturdy enough for museums, malls or arcades, sound localization suffered from reflections off the screens, and it was hard to photograph.[1] They considered six projected sides better than four but noted that rear projection on the floor and ceiling would have required raising the structure 10 ft.[1] The floor screen was a painted floor board and was a source of light spillage.[1]
The 2013 CAVE2 paper described the original CAVE's resolution (4 megapixels) as limited and its contrast as poor. It also noted that projection CAVEs need specially designed rooms and low ambient light, and that high-resolution projectors are expensive and need regular calibration and bulb replacement.[8] A 2011 review led by DeFanti gave a typical CAVE as four to six 3 m by 3 m rear-projected sides, usually housed in a room of about 10 m by 10 m by 10 m to leave space for the projectors, and argued that future CAVEs would use tiled flat-panel displays.[11]
Later CAVE systems
| System | Operator | Year | Description |
|---|---|---|---|
| BAT CAVE | EVL, University of Illinois Chicago | 2001 | Christie Mirage 5000 DLP active stereo projectors and near-black screens[2] |
| C6 | Virtual Reality Applications Center, Iowa State University | 2000; upgraded 2007-2008 | Six-sided 10 ft cube (four walls, floor and ceiling) with 24 Sony SRX-S105 projectors at 4096x4096 per surface, more than 100 million pixels in total, engineered by Mechdyne[12][13] |
| StarCAVE | Calit2, UC San Diego | 2007 | Five-sided pentagonal room with 15 rear-projected walls and two floor screens, 34 HD projectors, over 68 million pixels[14][15] |
| CAVE2 | EVL, University of Illinois Chicago | 2012 | Cylindrical room of 72 passive stereo LCD panels, about 320 degrees of view[16] |
| SunCAVE | Qualcomm Institute, UC San Diego | 2017 | Successor to the StarCAVE with 70 screens driven by 35 PCs with 70 GPUs[15] |
At Iowa State, the 2007 C6 upgrade used a Hewlett-Packard computer cluster with 96 graphics processing units and an InterSense wireless head tracker and wand, according to Campus Technology.[13] The StarCAVE, designed by a Calit2 team that included DeFanti, drove each pair of its projectors from one quad-core Linux PC with dual graphics processors, used a multi-camera wireless tracking system and cost less than $1 million, according to UC San Diego.[14] UC San Diego says the StarCAVE was first unveiled in 2007 and became the SunCAVE in the summer of 2017; the SunCAVE was built panel by panel with National Science Foundation funds.[15]
CAVE2
CAVE2 is EVL's second-generation design, which it calls a "Hybrid Reality Environment". It is about 24 ft in diameter and 8 ft tall and uses 72 off-axis-optimized passive stereo 3D LCD panels in 18 columns of four, driven by a 36-node computer cluster, with a 20-speaker audio system, a 10-camera optical tracking system and a 100 Gbit/s network connection.[16][8] It shows 37 megapixels in stereoscopic 3D or 74 megapixels in 2D, which EVL describes as almost 10 times the 3D resolution of the original CAVE and a horizontal visual acuity of 20/20.[16] Custom panels with shifted polarizers reduce ghosting in the top and bottom rows, and the tracking uses ten Vicon Bonita infrared cameras.[8] EdTech Magazine reported that Planar Systems configured the custom micropolarizers for the panels.[9] The room can run one fully immersive simulation, act as a 2D tiled display wall, or mix 2D and 3D windows, using EVL's SAGE software combined with the Omegalib VR middleware.[8]
CAVE2 debuted in October 2012, with development funded by the National Science Foundation (award CNS-0959053) and the US Department of Energy.[16] EdTech Magazine reported its cost as $926,000.[9] Mechdyne licensed the CAVE2 design in January 2013,[4] and by October 2013 Monash University in Australia had the second CAVE2, installed with EVL and Mechdyne, although it had not yet officially launched.[17]
Commercial systems
In March 2019 Mechdyne announced what it called the world's first virtual reality CAVE built with direct view LED display technology, available with up to six sides. The company said the displays need less maintenance and less facility space than projection-based CAVEs.[18] When licensing CAVE2, Mechdyne said it expected the main users to be universities, scientific research organizations, energy companies, and manufacturing and design firms.[4]
Applications
The CAVE was built for scientific visualization, and its designers wanted it to connect to remote supercomputers, data sources and scientific instruments.[1] Its wrap-around screens allowed "successive refinement": a user could navigate in real time, then request a detailed four-wall stereo image set from a supercomputer and keep looking around while it was displayed, which is impractical in a head-mounted display.[1] In 1993 collaborative projects were underway in non-Euclidean geometry, cosmology, meteorology and parallel processing.[1] EVL says its CAVE and OptIPortal display systems have been deployed to hundreds of research, industrial and educational users worldwide.[16]
See also
References
- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 1.19 1.20 1.21 1.22 1.23 1.24 1.25 1.26 1.27 1.28 1.29 1.30 1.31 1.32 1.33 1.34 1.35 1.36 1.37 1.38 Carolina Cruz-Neira, Daniel J. Sandin, Thomas A. DeFanti (1993). "Surround-Screen Projection-Based Virtual Reality: The Design and Implementation of the CAVE". Proceedings of SIGGRAPH '93 (20th Annual Conference on Computer Graphics and Interactive Techniques), pp. 135-142. ACM. doi:10.1145/166117.166134. https://www.evl.uic.edu/documents/siggraph93-cave-cruz-neira.pdf. Retrieved 2026-09-27.
- ↑ 2.0 2.1 2.2 2.3 2.4 "The CAVE Virtual Reality Theater". Electronic Visualization Laboratory, University of Illinois Chicago. https://www2.evl.uic.edu/entry.php?id=1769. Retrieved 2026-09-27.
- ↑ 3.0 3.1 Andrew E. Johnson, Luc Renambot, G. Elisabeta Marai, Daria Tsoupikova, Michael E. Papka, Lance Long, Dana Plepys, Jonas Talandis, Maxine D. Brown, Jason Leigh, Daniel J. Sandin, Thomas A. DeFanti (2024). "Electronic Visualization Laboratory's 50th Anniversary Retrospective: Look to the Future, Build on the Past". PRESENCE: Virtual and Augmented Reality, vol. 33, pp. 77-127. MIT Press. https://doi.org/10.1162/pres_a_00421. Retrieved 2026-09-27.
- ↑ 4.0 4.1 4.2 4.3 "Mechdyne Corporation Licenses CAVE2 Hybrid Reality Environment from the University of Illinois at Chicago". Electronic Visualization Laboratory, University of Illinois Chicago. Mechdyne Corporation (press release). 2013-03-05. https://www2.evl.uic.edu/entry.php?id=1103. Retrieved 2026-09-27.
- ↑ 5.0 5.1 "Virtual Reality at Illinois". VR@Illinois. University of Illinois Urbana-Champaign. https://vr.illinois.edu/virtual-reality-at-illinois/. Retrieved 2026-09-27.
- ↑ "SIGGRAPH 1992: 19th Annual Conference on Computer Graphics and Interactive Techniques". ACM SIGGRAPH History Archives. https://history.siggraph.org/conference/siggraph-1992-19th-annual-conference-on-computer-graphics-and-interactive-techniques/. Retrieved 2026-09-27.
- ↑ Carolina Cruz-Neira, Daniel J. Sandin, Thomas A. DeFanti, Robert V. Kenyon, John C. Hart (1992-06). "The CAVE: Audio Visual Experience Automatic Virtual Environment". Communications of the ACM, vol. 35, no. 6, pp. 64-72. https://doi.org/10.1145/129888.129892. Retrieved 2026-09-27.
- ↑ 8.0 8.1 8.2 8.3 8.4 Alessandro Febretti, Arthur Nishimoto, Terrance Thigpen, Jonas Talandis, Lance Long, JD Pirtle, Tom Peterka, Alan Verlo, Maxine Brown, Dana Plepys, Dan Sandin, Luc Renambot, Andrew Johnson, Jason Leigh (2013-03-04). "CAVE2: A Hybrid Reality Environment for Immersive Simulation and Information Analysis". Proceedings of SPIE, vol. 8649, The Engineering Reality of Virtual Reality 2013, 864903. doi:10.1117/12.2005484. https://www.evl.uic.edu/documents/spie13paper-final-2.pdf. Retrieved 2026-09-27.
- ↑ 9.0 9.1 9.2 Brad Grimes (2013-01-30). "University of Illinois at Chicago: Virtual Reality's CAVE Pioneer". EdTech Magazine. https://edtechmagazine.com/higher/article/2013/01/university-illinois-chicago-virtual-realitys-cave-pioneer. Retrieved 2026-09-27.
- ↑ Kwanguk Kim, M. Zachary Rosenthal, David J. Zielinski, Rachael Brady (2014-03). "Effects of virtual environment platforms on emotional responses". Computer Methods and Programs in Biomedicine, vol. 113, no. 3, pp. 882-893. PMID 24440136. https://doi.org/10.1016/j.cmpb.2013.12.024. Retrieved 2026-09-27.
- ↑ Thomas DeFanti, Daniel Acevedo, Richard Ainsworth, Maxine Brown, et al. (2011). "The future of the CAVE". Central European Journal of Engineering (now Open Engineering), vol. 1, no. 1. https://doi.org/10.2478/s13531-010-0002-5. Retrieved 2026-09-27.
- ↑ "C6". Virtual Reality Applications Center, Iowa State University. https://www.vrac.iastate.edu/facilities/c6/. Retrieved 2026-09-27.
- ↑ 13.0 13.1 Paul McCloskey (2007-04-17). "Iowa State To Unveil C6, Upgraded Virtual Reality Room". Campus Technology. https://campustechnology.com/articles/2007/04/iowa-state-to-unveil-c6-upgraded-virtual-reality-room.aspx. Retrieved 2026-09-27.
- ↑ 14.0 14.1 Doug Ramsey (2008-09-18). "3D Virtual Reality Environment Developed at UC San Diego Helps Scientists Innovate". Phys.org. University of California, San Diego. https://phys.org/news/2008-09-3d-virtual-reality-environment-uc.html. Retrieved 2026-09-27.
- ↑ 15.0 15.1 15.2 Katie E. Ismael (2019-08-15). "From Star to Sun: The Qualcomm Institute's CAVE Expands". UC San Diego Today. https://today.ucsd.edu/story/from-star-to-sun-the-qualcomm-institutes-cave-expands. Retrieved 2026-09-27.
- ↑ 16.0 16.1 16.2 16.3 16.4 "CAVE2: Next-Generation Virtual-Reality and Visualization Hybrid Environment for Immersive Simulation and Information Analysis". Electronic Visualization Laboratory, University of Illinois Chicago. https://www2.evl.uic.edu/entry.php?id=2016. Retrieved 2026-09-27.
- ↑ "Australia's Monash University introduces world's second CAVE2 System". Electronic Visualization Laboratory, University of Illinois Chicago. 2013-10-19. https://www2.evl.uic.edu/entry.php?id=1134. Retrieved 2026-09-27.
- ↑ Mechdyne Corporation (2019-03-19). "Mechdyne Announces the World's First Virtual Reality CAVE Using Direct View LED". PR Newswire. https://www.prnewswire.com/news-releases/mechdyne-announces-the-worlds-first-virtual-reality-cave-using-direct-view-led-300814687.html. Retrieved 2026-09-27.