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Now there’s nothing wrong in taking these factors into consideration, after all they are important; but they must not be allowed to overide the most basic of requirements, which is that there will almost always be an easily identifiable optimised location for the camera, and that quite simply is where it should be placed.
So what of this ‘Cone of Containment’ concept I hear you ask; well, all lenses allow a camera to effectively cover an area which is cone shaped.
In practical terms, the effective cone is actually more like a four sided pyramid, with the point at the lens, and the base increasing in size as you move away from the camera.
The important point to remember is that wide angle lenses produce large cones, and telephoto lenses result in quite narrow cones.
Now, if you consider how people move, and indeed vehicles for that matter, certain basic rules apply.
Customers rarely if ever drop through ceilings to the floor below, they seldom pass through brick walls, and vehicles generally drive on the road (but not always!).
Straight line motion is very popular in the real world, although if you watch people moving around in large spaces like a train station or an airport, they do indeed move in relatively straight lines, it’s just unfortunate that the lines all head off in differant directions .... unless of course, you choose your viewpoint carefully, or manage the pedestrian flow.
If you look at a station concourse, the chances of producing Identification level Evidential Quality Recordings (EQR) of individuals using everyday performance cameras, is only slightly more than that of Doktor Jon becoming a multi millionaire before his next birthday!
Then again, instead of trying to concentrate on the entire concourse itself, if you locate optimised CCTV cameras to monitor the key access points or ‘Gateways’, there is a much greater probability of producing identifiable recordings.
Wide angle cameras can then be applied to provide general overviews (contextual images) of pedestrian activity on the concourse. In very large or complex areas, modern HD standard and MegaPixel cameras may be very well suited to this type of application, but the temptation to go with wide angle lenses should be resisted wherever possible.
So how do we apply this simple idea of a ‘Cone of Containment’, to make CCTV cameras significantly more efficient?.
Doktor Jon explains the 'Cone of Containment'- cont.
Now if you ask an average installer where to place a CCTV camera, in no particular order the answers are likely to revolve around:-
1) ... easy access for installing cables,
2) ... ease of providing a suitable power supply,
3) ... "gives a good view mate", and
4) ... the least problematic material on which to fix the bracket.