Closed-circuit television: Difference between revisions

== Uses ==

=== Crime prevention ===

[[File:Video surveillance sign.jpg|thumb|Sign warning that premises are watched by CCTV cameras]]

{{further|crime prevention|predictive policing}}

It has been argued that problems of selection bias and endogeneity can be addressed by stronger research designs such as [[randomized controlled trials]] and [[natural experiments]]. A 2017 review published in [[Journal of Scandinavian Studies in Criminology and Crime Prevention]] compiles seven studies that use such research designs. The studies included in the review found that CCTV reduced crime by 24-28% in public streets and urban subway stations. It also found that CCTV could decrease unruly behaviour in football stadiums and theft in supermarkets/mass merchant stores. However, there was no evidence of CCTV having desirable effects in parking facilities or suburban subway stations. Furthermore, the review indicates that CCTV is more effective in preventing property crimes than in violent crimes.<ref>{{Cite journal|title = Surveillance cameras and crime: a review of randomized and natural experiments|journal = Journal of Scandinavian Studies in Criminology and Crime Prevention|date = 2017|pages = 210–222|volume = 18|issue = 2| author = Gustav Alexandrie|doi = 10.1080/14043858.2017.1387410|s2cid = 149144413}}</ref>

 

Another question in the effectiveness of CCTV for policing is around uptime of the system; in 2013 City of Philadelphia Auditor found that the $15M system was operational only 32% of the time.<ref>{{cite web|url=http://www.viakoo.com/orphaned-video-system-in-philadelphia/|title=Orphaned Video System in Philadelphia?|date=May 2015|access-date=29 July 2015|archive-date=28 October 2017|archive-url=https://web.archive.org/web/20171028042359/https://www.viakoo.com/orphaned-video-system-in-philadelphia/|url-status=dead}}</ref> There is strong anecdotal evidence that CCTV aids in detection and conviction of offenders; for example, UK police forces routinely seek CCTV recordings after crimes.<ref>[https://www.telegraph.co.uk/news/uknews/crime/10512087/10484338Police-are-failing-to-recover-crucial-CCTV-footage-new-figures-suggest.html?fbHow&goback=%2Egde_1889337_member_5817222616544473092 "Police are failing to recover crucial CCTV footage, new figures suggest"], The Daily Telegraph</ref> Moreover, CCTV has played a crucial role in tracing the movements of suspects or victims and is widely regarded by anti-terrorist officers as a fundamental tool in tracking terrorist suspects. Large-scale CCTV installations have played a key part of the defenses against terrorism since the 1970s. Cameras have also been installed on [[public transport]] in the hope of deterring crime.<ref>[http://news.bbc.co.uk/1/hi/england/hereford/worcs/3101016.stm "CCTV to drive down cab attacks"], BBC</ref><ref>[http://news.bbc.co.uk/1/hi/england/bristol/4295859.stm "Taxi CCTV cameras are installed"], BBC</ref>

 

== Prevalence ==

[[File:Surveillance cameras mapped.png|thumb|left|A crowdsourced map of CCTV cameras near [[Grande Arche]] using [[OpenStreetMap]] data<ref>{{cite web |url=http://osmcamera.tk/index.php?lat=48.89280064&lon=2.2415328&zoom=17&layer=osm |title=The CCTV Map |website=osmcamera |author=khris78 |access-date=2 August 2014 |url-status=dead |archive-url=https://web.archive.org/web/20141025180244/http://osmcamera.tk/index.php?lat=48.89280064&lon=2.2415328&zoom=17&layer=osm |archive-date=25 October 2014 }}</ref>]]

[[File:SurveillanceCamera4.jpg|thumb|upright|A surveillance camera, aimed at a public street (Kungsgatan) in Stockholm, Sweden, mounted on top of the pole]]

 

 

{{DEFAULTSORT:Closed-Circuit Television}}

[[Category:Applications of computer vision]]

[[Category:Assistive technology]]