Definition Augmented reality (AR) refers to computer displays that add virtual information
to a user's sensory perceptions. Most AR research focuses on see-through devices,
usually worn on the head that overlay graphics and text on the user's view of
his or her surroundings. In general it superimposes graphics over a real world
environment in real time. Getting the right information at the right time
and the right place is key in all these applications. Personal digital assistants
such as the Palm and the Pocket PC can provide timely information using wireless
networking and Global Positioning System (GPS) receivers that constantly track
the handheld devices. But what makes augmented reality different is how the information
is presented: not on a separate display but integrated with the user's perceptions.
This kind of interface minimizes the extra mental effort that a user has to expend
when switching his or her attention back and forth between real-world tasks and
a computer screen. In augmented reality, the user's view of the world and the
computer interface literally become one.
the extremes of real life and Virtual Reality lies the spectrum of Mixed Reality,
in which views of the real world are combined in some proportion with views of
a virtual environment. Combining direct view, stereoscopic video, and stereoscopic
graphics, Augmented Reality describes that class of displays that consists primarily
of a real environment, with graphic enhancements or augmentations.In Augmented
Virtuality, real objects are added to a virtual environment. In Augmented reality,
virtual objects are added to real world. An AR system supplements the real world
with virtual (computer generated) objects that appear to co-exist in the same
space as the real world. Virtual Reality is a synthetic environment Comparison
between AR and virtual environments.The
overall requirements of AR can be summarized by comparing them against the requirements
for Virtual Environments, for the three basic subsystems that they require.
Scene generator: Rendering is not currently one of the major problems in AR. VE
systems have much higher requirements for realistic images because they completely
replace the real world with the virtual environment. In AR, the virtual images
only supplement the real world. Therefore, fewer virtual objects need to be drawn,
and they do not necessarily have to be realistically rendered in order to serve
the purposes of the application.
Display device: The display devices used in AR may have less stringent requirements
than VE systems demand, again because AR does not replace the real world. For
example, monochrome displays may be adequate for some AR applications, while virtually
all VE systems today use full color. Optical see-through HMDs with a small field-of-view
may be satisfactory because the user can still see the real world with his peripheral
vision; the see-through HMD does not shut off the user's normal field-of-view.
Furthermore, the resolution of the monitor in an optical see-through HMD might
be lower than what a user would tolerate in a VE application, since the optical
see-through HMD does not reduce the resolution of the real environment.
Tracking and sensing: While in the previous two cases AR had lower requirements
than VE, that is not the case for tracking and sensing. In this area, the requirements
for AR are much stricter than those for VE systems. A major reason for this is
the registration problem.