The Head Mounted Display
	The Dataglove

The first head-mounted display (HMD)

The first viewing helmet was developed by the Philco Corporation in 1955-56. It was built from an American footballer’s helmet equipped with just one monitor and a system of mirrors in front of the user’s eyes. The imagery was provided by a remote camera which moved at the same time and in the same direction as the helmet’s wearer. Almost ten years later, at the University of Utah, Ivan Sutherland, one of the pioneers of computer-generated images and also of virtual reality, developed a head-mounted viewer that resembled a pair of glasses, incorporating cathode-ray tubes in the sides and, once again, a system of mirrors in front of the viewer’s eyes. A sensor suspended from the ceiling — giving the device its name, the Sword of Damocles —, allowed for the images to be co-ordinated in real time with the changing position of the user’s head.
Towards the end of the 1970s, the American Navy started working on the use of head-mounted display devices in the field of underwater exploration with remote-controlled robots. In the early 80s, the Architecture Machine Group managed to devise a low cost helmet using liquid crystal displays, while researchers at the University of Tsukuba in Japan were developing similar techniques for the remote control of robots. At the same time, the US Air Force was working to develop systems whereby pilots could see computer-generated data superimposed onto the land they were flying over, and images of their flight path even in conditions of zero visibility. Since 1985, NASA has been working on the possibilities of using stereoscopic viewing helmets in space stations and other space missions. This program was the first head-mounted display system to also include stereophonic sound, speech input, and instrumented gloves to interact with virtual objects.

The dataglove

The earliest device for interactivity in a virtual environment and with virtual objects was the dataglove developed at NASA Ames. These gloves were fitted with special sensors to measure the bend of the fingers and equipped with a magnetic tracking system which allowed for the glove, and the hand inside it, to be followed in three-dimensional space. More advanced equipment is available today, such as the Cyberglove built by the Virtual Technologies company, for high-resolution activity, or the Mattel Powerglove which is used for example in Nintendo games. Japanese researchers at the University of Tsukuba have developed a device with mechanical force-feedback sensors. The user puts his hand into the device and can manipulate a virtual ball and also feel a simple virtual surface of the object. But there is still no device which can give the user the impression of holding a solid object in the hand and ability to handle it freely. This is a major research challenge and many research programmes are trying to achieve the capability of user reactions such as this.

VRML (Virtual Reality Modeling Language)

The Virtual Reality Modeling Language is a language for describing multi-participant interactive simulations-virtual worlds networked via the global Internet and hyper-linked with the World Wide Web.
The first version of VRML allows for the creation of virtual worlds with limited interactive behavior. These worlds can contain objects which have hyper-links to other worlds, HTML documents or other valid MIME types. VRML was conceived in the spring of 1994 at the first annual World Wide Web Conference in Geneva, Switzerland. Tim Berners-Lee and Dave Raggett organized a session to discuss Virtual Reality interfaces to the World Wide Web. The term Virtual Reality Markup Language was coined, and the group resolved to begin specification work after the conference. The word "Markup" was later changed to "Modeling" to reflect the graphical nature of VRML.

For more informations:
http://www.sdsc.edu/vrml

Some interface designs used in Virtual reality

VR Hardware such as

-Wands, the simplest of the interface devices, come in all shapes and variations.
-trampoline into a pseudosurf board
-attached sensors to a mock tractor cab
-Stairsteppers are an example of the limitless manifestations of interface devices Types of VR
-Window on World Systems (WoW)
-Video Mapping
-Immersive Systems
-Telepresence
-Image Generators
-Manipulation and Control Devices
-Mixed Reality
-Position Tracking
-Stereo Vision