Know what ID CCTV quality really is

[CCTVguru]

Thank God spring has arrived and it's a lovely 22 degree day here in Adelaide.

In the wonderful days of analogue CCTV, I was comfortable with the requirements of getting ID quality face images based on a 4CIF recording but with so many different resolutions was unsure how much gain more megapixels was giving. As a sales person, it is easy to say "throw a megapixel camera in" but are we really adding value?

The following is an extract of an article written on and shows exactly what impact the common resolutions will have.

When we are working with cameras that weed to ID someone, such as an entry door or counter, Australian Standards say we need 352 pixels per metre to get 88 pixels from the chin to the hair of a person's face. From this if we work on a standard lens angle (so CCD/CMOS size can be ignored) of 60 degrees we can get a set of guide lines to work from when designing. We want to see at least one camera in every site have at least one region that is red (or grey if it is our own staff being monitored) that the person will pass through.




Starting at 4CIF, which is an analogue camera on a good DVR we can ID someone at a maximum of 1.5 metres from the camera and that is before taking into account the DVR compression, angle of view and frame rate. This was a really easy one to setup in the field as the person needs to occupy
100% of the scene height to be ID quality or 50% if you already know them.




720p HD covers ID to nearly 3m and recognise to 6m




1080p HD covers ID to 4.5m and recognise to 9m




1.3MP covers ID to 3m and recognise to 6m




2MP covers ID to 3.7m and recognise to 7.4m




3MP covers ID to 5m and recognise to 10m




5MP covers ID to 6.3m and recognise to 12.6m




If you need to change the lens angle, just multiply these numbers by the increased proportion. EG 60 degrees is a 4mm lens on a 1/3" CCD. If I changed it to an 8mm lens, I will get 30 degrees and double the ID range so on a 720p camera ID up to 6 metres.



We offer a 3D drawing design service that will give you a competitive edge in your tender responses, showing you know more about CCTV than your competitors.
Each design includes range charts indicating compliance to Australian Standards AS4806 and a 3D image of the scene as the camera will view it.