Recently, there has been much discussion about the differences between (and resulting advantages of) thermal cameras and traditional visual cameras for surveillance purposes, writes Laurence Smith, executive at Graphic Image Technologies.
Visual cameras use light to create images, while thermal cameras rely on heat to translate an image into a visual picture. Due to the dependence on light to create images, visual cameras have an innate shortcoming – much like the human eye if the weather or lighting conditions are bad, the visual camera’s imaging will be adversely affected while thermal cameras will present a consistent image regardless of weather and lighting.
It is this major disparity between visual and thermal cameras that makes them suited to different tasks which means that when planning a security surveillance system, it is not an either-or decision. It is not a case of choosing between visual or thermal cameras, as both have their strengths, and all that is required to maximise on these strengths is strategic planning and the correct application of video analytics software.
Match the camera to the task
Thermal cameras are designed for placement where lighting is an issue. Since the sensor picks up a heat signal rather than a visual one, it will work regardless of weather conditions, presenting a consistent image. On the other hand, visual cameras are affected by the absence of light, which has an impact on the range of the camera.
A range of 300 metres during the day, for example, is reduced to 50 metres at night in the absence of decent floodlighting. While in theory thermal and visual cameras should be able to achieve similar ranges, provided that the appropriate lenses are in place, in reality visual cameras simply do not have the same reach as thermal.
This weakness, however, is offset by the ability to achieve ultra-high definition resolutions using 4K cameras – such cameras deliver an exceptional picture that it is possible to visually verify physical details, like hair colour, facial features, vehicle registration plates and the like. Such detailed visual imagery is simply not possible with thermal cameras.
As a result of their specific strengths and weaknesses, thermal cameras are best suited to the protection of large perimeters, performing an intrusion prevention task. Visual cameras are suited to applications where detail is necessary such as entry and exit points as well as the interior of buildings and warehouses. This means it’s essential to have a combination of both in a surveillance system.
Unlock the best of both, with smart video analytics
The key to maximising the effectiveness of both thermal and visual cameras is the video analytics component. It is now possible to use a computer or analytics engine to do a lot of the work that a human would have had to do in the past.
By setting up rules within the video analytics system, it is possible to set up alerts for certain scenarios, to trigger an appropriate security response ensuring personnel can quickly identify potential threats and incidents and execute on these, without delay.
Video analytics enables what is essentially “blank screen monitoring”, in that the system will give notifications of risks according to specific rules set up, and guards are not required to constantly have their eyes on the camera feeds.
Using sophisticated algorithms and pixel-by-pixel analysis, video analytics can pick up on the smallest of details provided by visual and thermal cameras, while thermal cameras catch everything that visual cameras might miss, given their vulnerability to being blinded by bright light, lack of light and adverse weather conditions. In short, video analytics removes the scope for human error and drastically improves monitoring efficiency.
By automating many of the functions previously performed by humans, technology makes the surveillance element of security far more reliable.
The right combination of modern 4K cameras, with thermal cameras on perimeters, combined with video analytics software in the CCTV setup, can ensure that the strengths of both cameras work to negate their respective weaknesses.
Without a doubt, thermal cameras are the best 24-hour imaging option, while 4K cameras simply can’t be beat when it comes to taking note of the details. It is thus practical for businesses to stop debating the differences between thermal and visual cameras and instead, to implement a well-planned surveillance system that is equipped with both types of cameras, fuelled by the power of smart video analytics software.