•Virtual reality is an artificial environment that is created with software and presented to the user in such a way that the user suspends belief and accepts it as a real environment.
•Virtual reality can be defined as an upcoming technology that makes users feel in a Virtual Environment (VE).
•To “enter” a virtual reality, a user dons special gloves, earphones, and goggles, all of which receive their input from the computer system. In this way, at least three of the five senses are controlled by the computer. In addition to feeding sensory input to the user, the devices also monitor the user’s actions.
•The goggles, for example, track how the eyes move and respond accordingly by sending new video input.
•That person becomes part of this virtual world or is immersed within this environment and whilst there, is able to manipulate objects or perform a series of actions.
•Other terms for virtual reality include cyberspace, artificial reality, augmented reality and telepresence.
Components of a VE:
•The visual displays that immerse the user in the virtual world and block out contradictory sensory impressions from the real world.
•The graphics rendering system that generates the ever changing images at 20 to 30 frames per second.
•A tracking system that continuously informs the position and orientation of the user’s movements.
VR experience in general it should include:
•3d images that appear to be life sized from the perspective of the user.
•The ability to track a user’s motions, particularly his head and eye movements, and correspondingly adjust the images on the user’s display to reflect the change in perspective.
Latency
•Lag time between when a user acts and when the virtual environment reflects that action is called latency.
•Latency usually refers to the delay between the time a user turns his head or moves his eyes and the change in the point of view, though the term can also be used for a lag in other sensory outputs.
Techniques
•One of the technique used to create a virtual environment is projection based. The display images are projected on the multi screen spaces ranging from two to six screens.
•Both floor and ceiling uses a rear projection while the other four screens yield large surrounding views for both panning actions and looking down.
•Consequently objects inside the space could be walked around and virtual entreat to be touched.
•VE systems need a way to display images to a user. Many systems use HMDs, which are headsets that contain two monitors, one for each eye. The images create a stereoscopic effect, giving the illusion of depth.
•Other VE systems project images on the walls, floor and ceiling of a room and are called Cave Automatic Virtual Environments (CAVE).
•Tracking systems analyze the orientation of a user’s point of view so that the computer system sends the right images to the visual display.
Development
•Virtual Reality Modeling Language (VRML)- the earliest three dimensional modeling language for the Web.
•X3D – the language that replaced VRML as the standard for creating virtual environments in the Internet.
•Collaborative Design Activity (COLLADA) – a format used to allow file interchanges within three dimensional programs.
Applications
•Virtual reality games.
•Some architects create virtual models of their building plans so that people can walk through the structure before the foundation is even laid.
•Car companies have used VR technology to build virtual prototypes of new vehicles, testing them thoroughly before producing a single physical part.
•Virtual environments are used in training programs for the military, the space program and even medical students.
•Another medical use of VR technology is psychological therapy.They use virtual environments as a form of exposure therapy, where a patient is exposed under controlled conditions to stimuli that cause him distress.
References: engineersgarage ; howstuffworks
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