Observers call it magic. Writers say it's Alice's wonderland. Engineers refer to it as science. The popular term for the imaginary world that looks, sounds and feels real is "virtual reality." Virtual reality is a phenomena with a lot of promise and a lot of technological difficulties that have to be solved,"

It's a technology that I think is best looked at as a new medium, in the same way that film and television was a new medium at one time. It took 50 years from when the motion picture projector was patented in 1891 until techniques and technology had improved to the point where a film like 'Citizen Kane' could be made.

Virtual Reality is generally a Computer Generated (CG) environment that makes the user think that he/she is in the real environment. One may also experience a virtual reality by simply imagining it, like Alice in Wonderland.

The virtual world is hosted on a computer in the form of a database (e.g. terrain database or environment database). The database resides in the memory of the computer. The database generally consists of points in space (vertices), as well as textures (images). Vertices may be connected to form planes, commonly referred to as polygons. Each polygon consists of at least three vertices. The polygon could have a specific color, and the color could be shaded, or the polygon could have a texture pasted onto it. Virtual objects will consist of polygons. A virtual object will have a position (x, y, z), an orientation (yaw, pitch, roll) as well as attributes (e.g. gravity or elasticity).

The virtual world is rendered with a computer. Rendering involves the process of calculating the scene that must be displayed (on a flat plane) for a virtual camera view, from a specific point, at a specific orientation and with a specific field of view (FOV). In the past the central processing unit (CPU) of the computer was mainly used for rendering (so-called software rendering). Lately we have graphics processing units (GPUs) that render the virtual world to a display screen (so-called hardware rendering). The GPUs are normally situated on graphics accelerator cards, but may also be situated directly on the motherboard of the computer. Hardware rendering is generally much faster than software rendering.

Objects in the virtual world may be manipulated by means of a Data Glove. A data glove measures the flexure (bend) of the user's fingers. The user may grab a virtual object and put it at a different spot. The user may also throw the object. The position (x, y, z) and orientation (yaw, pitch, roll) of the user's hand is measured with a 6 DOF tracker. If it is a force-feedback data glove, the user will also be able to deform the virtual object, and feel the object (e.g. a tennis ball) resisting the deformation.

In order to navigate (e.g. walk or fly) in the virtual world, a Space Controller is used. The space controller could be a normal joystick, or a computer mouse. For example, when the mouse is moved forward, the user moves forward in the virtual world, when it is moved to the left, the user moves to the left, etc. Force-feedback joysticks or mice could provide hap tic cues to the user, e.g. when the user moves into a virtual wall. Normal joysticks and computer mice are usually used in Desktop VR Systems. In Immerse VR Systems we normally use baseless joysticks as space controllers. This enables the user to leave the desktop and to interact with the virtual world while standing up.

It is also possible for different users to share the same virtual world. This is normally achieved by connecting the host computers to a computer network. Each user's host computer broadcasts the position and orientation of the user in the virtual world. The users may therefore 'see' each other in the virtual world. In fact, users will see representations, referred to as avatars, of each other in the virtual world. They will be able to interact; working together or competing. The sharing of virtual worlds is generally referred to as 'shared virtual worlds', or as 'networked virtual reality'.

Sight and hearing are the main human senses currently used to experience virtual worlds. Touch (as in tactile- and force-feedback) is becoming more commonplace. Smell dispensers are entering the marketplace, enabling the user to smell the virtual world as well. Taste dispensers will follow soon.

APPLICATIONS OF VIRTUAL REALITY (VR)

Virtual Reality is an ideal training and visualization medium.

VR is ideal for the training of operators that perform tasks in dangerous or hazardous environments. The trainee may practice the procedure in virtual reality first, before graduating to reality-based training. The trainee may be exposed to life-threatening scenarios, under a safe and controlled environment. Examples of dangerous or hazardous environments may be found in the following fields:

Aviation, Automotive, Chemical, Defense, High Voltage, Industrial, Marine, Medical, Mining and Nuclear Energy