Why do I say this? During my travels in and out of boardrooms, numerous times, I came across the statement that: “Optical cameras are a much better solution than thermal cameras, installed on the perimeter, because you can identify the person entering the premises illegally.” Well, this is partially correct with a lot of clarification notes, and when something is partially correct then it can be partially incorrect as well. Half stays half.
To clarify the above statement as true, please allow me the following questions:
At what distance do you want to view an image?
Are you talking about a 24/7 operation, day and night-time?
Do you use video analytics or video motion detection?
What illumination are you using for night time operation?
How many false alarms can you handle?
Do you do offsite monitoring?
At first and the most simple of all, what can you see with the aid of these cameras?
The visible camera can see extremely far as the sun is shining and the entire world is illuminated and to be very sure we do not lie, the camera can see what you can see. You can see detail and colour during day time. The thermal camera can see extremely far as well, as mountains are heated with energy and the thermal radiation can be picked up, you can see the moon and the sun even. You can see objects, but not a lot of detail far away.
The visible camera can see nothing, or very limited over distance, as the scene must be illuminated and the reflective light must fall onto the detector. Illumination is attenuated by a matt surface and a wool type surface even more than a shiny reflective coating. The further the illumination the more power you need for the illuminator. The thermal camera can see the same as during daytime, with a small change in AGC. No illumination is required. As you can understand, there are a huge difference between an Optical image and a Thermal image. The first and most important aspect is, it is two very different technology type images. The optical camera can see what the eye can see and the thermal camera see beyond eye response. To put it into reality, have a look at the following:
Thermal cameras operate in a different space within the Electromagnetic spectrum than that of visible cameras. To summarize even further, thermal cameras detect slight variances in heat radiation and visible cameras can “see” what your eye can see and the visible cameras can “see” at night with the aid of Infrared Illumination or laser illumination.
As we have mentioned above, we have to discuss the following important aspect, “Illumination”. Thermal cameras need no illumination as it detects the subtle differences of heat radiation. Every object transmits heat, even ice. The minimum heat detected by a thermal camera is called “absolute 0ºKelvin = minus -273.15ºC. The sensitivity of the pixels of the thermal detector will give you the quality of the image and the selectivity of the scene. What you see during daytime, you will see at night time, but the average temperature will change which has a direct influence on the AGC, with no noticeable change in the image scene.
Visible cameras need illumination during night time operation. How much you will say. Well, if the illumination goes below the camera chip specification, the viewer will see that the camera will start showing a snowy image or some of the cameras will give you a good image, but with a drop in frame rate.
Needless to say, the IR or Laser illuminators and difference in specifications play a big role as well. The specifications will read a distance of 250m and you will pay below a ZAR1000.00 for each, only. Then you get the same distance illuminator for ZAR16,000.00 and you ask, “how is that possible?” The difference is actually very simple; you pay for what you get. These two products are not the same, or not even close to one another. The reality is, the further the illumination needed the more power you need, the more expensive the LED, the better the electronics must be in supporting and extending the MTBF of the hard working LED. Another consideration will be, if you want to see only, you do not need the same illumination as when you need to do detection. Even with video motion detection and video analytics, there is a vast difference in illumination power needed for effective detection.
The next item then leads to the distances needed between the camera positions. If topography is not an issue and the area is fairly flat and straight, then we look at the difference between thermal and optical.
The difference in price between a visible camera and a thermal camera then it can be seemed huge. Again, that is half the truth as we consider one aspect only. If you look at the maximum distance, you can get with a visible camera with the aid of an effective illuminator, you will be surprised if you get 120m (stretching the limits). Thermal cameras can give you a very effective detection range of 500m without any illumination.
The differences in amount of cameras, added the infrastructure and civil work. Suddenly, you will have a distance, where thermal cameras and visible cameras are at the same price, any further, it will be cheaper to install thermal cameras. Needless to say, this will have a direct influence on the maintenance contract, the recording space, the off-site monitoring alarms etc.
The last point I would like to raise is the Cost of Ownership over a 5 year period. More cameras, as explained above, with IR illuminators will definitely cost more to maintain and the hidden cost will be more, especially the power portion thereof. Our biggest drive is to support the customer, in giving the best solution, will be based on the most cost effective technology and solution in for filling the needs of the customer with emphases on the cost and longevity of the products.
To summarize, it is better to view the perimeter area, by using the 80/20 principle, to detect the possible intruder, well before the detection occur, if possible warn the intruder, all installed at a cost effective rate and to have best value for money, than installing an optical camera at short intervals, in trying to identify the individual where that capability is null and void during night-time anyway.