Augmented reality is still a growing field of research
despite the appearance of the technology in the 1960s
In virtual reality technology, the goal is to immerse a user
(viewer) within a virtual environment and so real objects
are excluded (or removed) from the environment and
replaced by computer generated equivalent models.
Virtual reality systems are usually classified according
to the degree of immersion in to three different level of
immersion, namely none, semi and fully immersive [6].
Non-immersive virtual reality systems generally do not
provide a stereo view of the environment. For example,
viewing a virtual reality environment on a typical computer
screen is a non-immersive experience as the virtual
environment exists only inside the computer screen and
interactions with the environment could be through the
keyboard, mouse or sometimes joystick devices. Semiimmersive
virtual reality systems provide a bigger view of
the computer generated environment. This is typically
archived through the use of a large screen device or
through the use of special eyewear or goggles. In semiimmersive
virtual reality systems, special input devices
such as wands, special gloves or controllers are also
commonly used. The user has a view of both the computer
generated environment and the surrounding real world
environment. A good example of a semi-immersive virtual
reality environment is a gaming station typically used for
car racing, in which the output is a combination of one or
more large-screen monitors and the input consists of a
mock-up driving station complete with steering wheel and
foot pedals. Fully-immersive virtual reality systems eliminate
completely any reference to the real world environment.
This may be archived by wearing special helmet
devices with mounted displays or by housing the user in
specially designed rooms called CAVEs (Cave Automated
Virtual Environments) where all the walls (including floor
and ceiling) are replaced by large screens monitors. In
both cases, the computer generated environment is projected
on the displays or monitors all around the user.
Fully-immersive environments also track the user movement
particularly orientation and may track the user’s
gestures and movement for input or optionally use wands,
special controllers or special gloves in case tracking of
individual finger movements is required for the simulated
environment.
Unlike virtual reality, in augmented reality, the goal is
not to exclude the real world but to “blend” additional
information or computer generated information with realtime
information from the real world around a viewer,
augmented reality systems are also called mixed reality
systems as they attempt to mix both real and virtual objects