Information Technology Reference
artificial and then not true, while VW always stands as real elements even if
it is a reality abstraction.
As far as AR techniques are concerned, there are many ranging from
databases to identification systems.
Generally speaking, on the basis of information stored in some remote
server, a system tries to recognize the environment and identify the real
objects in it by reading digital data such as pre-recorded videos or simple tags
attached to an object in the environment. Reading is made possible by some
wireless communication technology like, for instance, infrared (IR) or radio
frequency (RF) (Figure 4).
Other systems, especially those for external, try to identify the
environment and objects inside, by localizing a user and using a server-
provided map of the information to be displayed in each place. An example
of these systems is mobile-augmented reality system (MARS) that was
designed to provide a user with a virtual guide . The user equipment in
MARS original version is rather bulky. All the needed devices such as
notebook, batteries, pointing devices and a positioning system with 1 cm
accuracy, also capable of detecting and measuring head motion, are put in a
13-kg kit-bag to carry.
The MediaCups project  applies AR technologies to a coffee cup along
with sensors to detect the position and rotation (Figure 5). Furthermore,
it uses an accumulator that is wireless recharged by means of the saucer and
it communicates through IR with a network infrastructure.
Figure 4: Adhesive RFID tag.