CCTV Cameras
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Closed-circuit television (CCTV) is the use of video cameras to transmit a signal
to a specific, limited set of monitors. It differs from broadcast television in
that the signal is not openly transmitted, though it may employ point to point wireless
links. CCTV is often used for surveillance in areas that may need monitoring such
as banks, casinos, airports, military installations and convenience stores. The
increasing use of CCTV in public places has caused a debate over public surveillance
versus privacy. People can also buy consumer CCTV Systems for personal, private
or commercial use. A more advanced form of CCTV, utilising Digital Video Recorders
(DVR), provides recording for possibly many years, with a variety of quality and
performance options and extra features (such as motion-detection and email alerts).
In industrial plants, CCTV equipment may be used to observe parts of a process from
a central control room; when, for example, the environment is not comfortable for
humans. CCTV systems may operate continuously or only as required to monitor a particular
event.
A CCTV system may be installed where an operator of a machine cannot directly observe
people who may be injured by unexpected machine operation. For example, on a subway
train, CCTV cameras may allow the operator to confirm that people are clear of doors
before closing them and starting the train. Operators of an amusement park ride
may use a CCTV system to observe that people are not endangered by starting the
ride. A CCTV camera and dashboard monitor can make reversing a vehicle safer, if
it allows the driver to observe objects or people not otherwise visible.
The first CCTV cameras used in public spaces were crude, conspicuous, low definition
black and white systems without the ability to zoom or pan. Modern CCTV cameras
use small high definition colour cameras that can not only focus to resolve minute
detail, but by linking the control of the cameras to a computer, objects can be
tracked semi-automatically. For example, they can track movement across a scene
where there should be no movement, or they can lock onto a single object in a busy
environment and follow it. Being computerised, this tracking process can also work
between cameras.
Computerized monitoring of CCTV images is under development, so that a human CCTV
operator does not have to endlessly look at all the screens, allowing an operator
to observe many more CCTV cameras. These systems do not observe people directly.
Instead they track their behaviour by looking for particular types of body movement
behavior, or particular types of clothing or baggage. The theory behind this is
that in public spaces people behave in predictable ways. People who are not part
of the 'crowd', for example car thieves, do not behave in the same way. The computer
can identify their movements, and alert the operator that they are acting out of
the ordinary. |