I have just learned of the advantages of DORI. No, I’m not talking about Nemo’s little blue friend but the special feature I’ve discovered in my CCTV cameras installed by the licenced cabling technicians and security advisors at The Computer Workshop.
After having suffered a break-in and attempted break-in, my husband and I decided to invest in a CCTV system for added security. Little did I know how effective these cameras are.
The brazen thieves came back but this time, we had them on camera so I had the footage sent to the police. Because of DORI, they were able to recognise one of the perpetrators and arrest him.
Let me explain how it works.
DORI is a acronym used to define measurements for CCTV cameras.
You can select a certain camera for a job based on it’s DORI parameters.
DORI stands for Detection, Observation, Recognition and Identification.
The D (Detection) means that distance that you can reliably detect an object. The distance that you can reliably detect that the object is a car or a ute or even a person.
The O (Observation) means the distance that you can reliably observe what the object is doing. As this distance you should be able to observe the object was walking east, had a blue shirt on and seemed to be looking at cars in the street as an example.
The R (Recognition) means the distance that you can reliably recognise a person. The person may have been seen before and you may be able to recognise them again or at this distance you may be able to recognise a neighbour. You should be able to get good detail at this distance and a very good description of an offender or suspect for police.
The I (Identify) means the distance that without any doubt you could identify an individual. This might also apply to a number plate. This is also the distance that CCTV facial recognition will function reliably at.
When scoping an installation they look at boundaries and obstacles and general layout to select a camera with the correct DORI to perform for the site. A site might have a boundary fence 30m from the camera, there is no point looking too far past this so a logical choice would be a camera with a D level of 40 to 50m. Likewise if a camera is going to be 10m high, then an I level of 6m is not enough unless the offender is 4m off the ground.
The VIP Cameras they use have various DORI distances but the 4MP camera they use as our mainline camera has a DORI of D 56m, O 22m, R 11m and I of 6m.
So for a normal installation you would detect a person walking on the street in front of your business or home at 56m. You may see them earlier, but the certified reliable detection distance is 56m. If they keep walking closer you would be able to reliably observe what the individual is doing at 22m. You would then see detail of what they are up to and intentions of their actions (are they looking at your car for a way in for example). If the individual now proceeds to 11m from the camera you would see enough facial features and physical attributes to reliably recognise this individual. And if they proceed closer to 6m you would be without doubt able to identify them.
Given most suspects reported to police are in your front yard or inside your home, an I level of 6m is more than enough to achieve a good look at the individual.
More expensive cameras or different lens combinations allows for different DORI levels. With the VIP cameras we can supply fixed lens cameras with a DORI up to D 187m, O 75m, R 37m and I of 19m.
Of course with PTZ cameras the DORI is variable with the zoom of the camera.
DORI is of course measured under daylight lighting conditions, at night time your DORI lengths will be affected by lighting. Your Cameras will have an IR illumination system to assist with night time observation but most only cover to 20 to 30m from the camera.
If long range night time observation is a requirement then a camera with 50m IR illumination might give you a better result or installing additional IR floodlights to illuminate the observation area.
The DORI level is not just a ‘best guess’ put in place by the guy trying to sell you the camera system. The DORI level is put in place by an accredited lab under EN62676-4.
The difference between your ‘cheap’ no name cameras from your local hardware and professional cameras is a DORI level measurement.
I am yet to see a camera system from your local hardware or auto store that advises a DORI level meaning they have never been tested or certified to perform at any level.
