09-10-2010, 01:51 PM
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AN OVERVIEW OF VIRTUAL REALITY
ABSTRACT
In our world today we are surrounded by a wonderful array of technologies. We have assimilated many of these technologies into our everyday lives. Increasingly, these different technologies are becoming integrated to provide new capabilities and services. And most frequently a computer is the heart of this integration. This is the case with Virtual Reality - a so-called technology which actually is a very sophisticated integration of a number of technologies.
Virtual Reality is a computer-based technology which incorporates specialized input and output devices to allow the user to interact with and experience an artificial environment as if it were the real world. A VR system permits the user to explore a three-dimensional virtual - or artificial - environment and to interact with lifelike and/or fantasy elements created by the designer. In the virtual world, the user can do things as routine as throwing a ball or as fantastic as flying through space. And these things can be made to occur by something as simple as a hand gesture or a nod or (one day) a sound.
The following is an attempt to provide an introduction to virtual reality and some
of its basics.The technical paper provides a brief introduction to the new emerging technology followed by the two types of Virtual Reality systems viz. Desktop Virtual Reality System and Immersive Virtual Reality System.It also provides information about the various devices that are used for Immersive Virtual Reality System. Paper also covers the characteristics and applications of Virtual Reality. Finally the conclusion provides the importance of this emerging technology and attempts to give a brief look into how Virtual reality can affect the future.
INTRODUCTION TO VIRTUAL REALITY
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, but we will focus on computer generated virtual realities.
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). Virtual Reality (VR) provides the experience of perception and interaction through the use of sensors and effectors in a simulated environment. Advances in simulation technology allow computer resources to be interconnected with humans through the use of sensor systems and robotic devices. The goal of the simulation is to have a viewer see only the simulation -- as if the viewer were inside the simulation itself. Head motion and orientation are used to change the viewer’s visual perception, making the experience appear real.
The virtual environment (also sometimes referred to as a synthetic environment) may be experienced with a Desktop VR System, or with an Immersive VR System.
DESKTOP VR SYSTEM :- With Desktop VR a computer screen is normally used as the display medium. The user views the virtual environment on the computer screen. In order to experience the virtual environment, the user must look at the screen the whole time.
IMMERSIVE VR SYSTEM :- With Immersive VR the user is 'immersed in' or 'surrounded by' the virtual environment. This may be achieved by using:
.Head-Mounted Display (HMD)
The head-mounted display (HMD) was the first device providing its wearer with an immersive experience. Evans and Sutherland demonstrated a head-mounted stereo display already in 965. The EyePhone from VPL Research was the first commercially available HMD (989).
A typical HMD houses two miniature display screens and an optical system that channels the images from the screens to the eyes, thereby, presenting a stereo view of a virtual world. A motion tracker continuously measures the position and orientation of the user's head and allows the image generating computer to adjust
the scene representation to the current view. As a result, the viewer can look around and walk through the surrounding virtual environment.
2. Boom
The BOOM (Binocular Omni-Orientation Monitor) from Fakespace is a head-coupled stereoscopic display device. Screens and optical system are housed in a box that is attached to a multi-link arm. The user looks into the box through two holes, sees the virtual world, and can guide the box to any position within the operational volume of the device. Head tracking is accomplished via sensors in the links of the arm that holds the box.
3.Cave
The CAVE (Cave Automatic Virtual Environment) was developed at the University of Illinois at Chicago and provides the illusion of immersion by projecting stereo images on the walls and floor of a room-sized cube. Several persons wearing lightweight stereo glasses can enter and walk freely inside the CAVE. A head tracking system continuously adjust the stereo projection to the current position of the leading viewer.