C6
This order reflects the chronological creation order for these major systems.
A virtual environment enclosure is a large structure consisting of at least three surfaces where computer generated reality is displayed.
These surfaces consist of wall, ceiling, or floor sections that are connected together to form some shape of a room or alcove.
The oldest and most common shape is a three-walled cube with a fourth projection surface on the floor. The typical dimensions are 10 feet on each side, allowing multiple users to be in the virtual environment at the same time.
Images are generated by one or more computers and then reflected off mirrors to the projection screens. The viewpoint and movement through the environment are controlled by the primary user. The primary user has some type of
magnetic position tracking
device on their body to measure where they are looking, plus a control wand in their hand for directing their movement through the virtual environment. Most virtual environment enclosures display stereographic images,
which require all users to wear
some type of stereo glasses to view the environment. This is done to enhance the three-dimensional effect of the surround displays. One draw back is that except for the primary user, everyone is just along for the ride and may suffer from
simulator sickness.
Creating a virtual environment enclosure is costly both in money and space requirements. If both ceiling and floor hold projection surfaces, the space required is now at least three stories in height plus the distance required to bounce the
projections to both side walls. A totally enclosed space also requires that one wall be moveable to allow user to enter and leave without a physical joint in a projection surface that will destroy the 3-dimensional image effect.
CAVE - CAVE Automatic Virtual Environment
The first functional virtual environment enclosure was the CAVE (CAVE Automatic Virtual Environment).
CAVE is both a recursive acronym and a reference to "The Simile of the Cave" found in Plato's Republic, in which the philosopher explores the ideas of perception, reality, and illusion. Plato used the analogy of a person facing the back of a cave
alive with shadows that are his/her only basis for ideas of what real objects are.
It was developed at the University of Illinois at Chicago in 1991 and first displayed at SIGGRAPH '92.
(SIGGRAPH is the Special Interest Group for GRAPHics)Carolina Cruz-Neira, Daniel J. Sandin and Thomas A. DeFanti presented the background paper
"Surround-Screen Projection-Based Virtual Reality: The Design and Implementation of the CAVE" at SIGGRAPH '93 since they had missed the submission deadline for '92.
A typical CAVE's theater area sits in a 30'x20'x13' room, provided that the projectors' optics are folded by mirrors. The initial versions were created by taking a single continuous length of projection material and stretching 1/4 inch cables from floor to
ceiling for each of the front corners. This proved to destroy the 3-dimensional effect whenever the object being viewed was occluded by the cable. The floor panel was just a painted surface and at times reflected too much light from the walls. The
magnetic tracking and stereo sound equipment used for the first CAVE also had numerous short comings.
The CAVE is commercially available through Pyramid Systems, Inc., which in association with University of Illinois at Chicago, keeps a large network of technical and software support for CAVE users.
C2
The C2 was created at Iowa State University by Carolina Cruz-Neira and is based on her work at the University of Illinois at Chicago.
The picture at the beginning of this page was created in the C2 and is entitled "Fire Cave". In collaberation with the engineering department at Iowa State, The C2 attempted to correct several of the deficiencies of Dr. Cruz-Neira's earlier work.
Major improvements include shifting the floor projection from behind the user to in front of the user. This translates shadows in the users field of view on the floor to behind the user where they do not affect the display. The occlusion in the corners
was solved by pinching the sides together using clamps that did not cast shadows onto the screens. By using the Unistrut framework it better allowed aiming of the stereo speakers, enhance the 3-dimensional sounds of the environment.
CABIN - Computer Aided Booth for Image Navigation
Built at the University of Tokyo, the CABIN is a five walled virtual environment enclosure. It uses tempered glass for the floor and rear projection material for the three sides and ceiling.
This was a major undertaking and is supported by local and international industry.
NAVE - NAVE Automatic Virtual Environment
NAVE was created by the Georgia Tech Virtual Environments Group as an affordable virtual environment enclosure.
The project cost was near $60K and easily fits into a typical college laboratory room. Blueprints are available for download. The NAVE attempts to enhance the overall
immersion experience by using both the visual, and to a great extent, physical senses. This is done by having two individuals sit in a rumble chair with a force feedback joystick for control of motion. The sound system used is excellent and sends
vibrations throughout the enclosure, especially up through the floor. Fans and strobe lights are also employed to enhance the atmosphere and directly stimulate the users.
C6
The C6, a three-dimensional, full-immersion, synthetic environment is in the process of design and fabrication at Iowa State University. This facility will include a room where all four walls,
the floor and the ceiling are projection screens that are capable of displaying back-projected stereoscopic images, thus providing total immersion of the participants. Structural design is being planned in cooperation with MechDyne Corporation.
One wall of the C6 will be movable to allow participants to enter and exit the facility. The shell around the structures which covers projectors and screens will be required for light containment. The C2 and the C6 will be linked by dedicated fiber
enabling C6/C2-based research in collaboration across geographically separated virtual reality systems.
