Thermal imagers in video surveillance systems.

Video surveillance systems are rapidly gaining their place in the sun.

Perhaps no other area of ​​security systems is developing as dynamically as CCTV.

The widespread use of IP technologies provides truly unlimited possibilities in designing topology and scaling the system.

Multi-pixel video cameras improve the image quality many times over compared to the already ancient PAL, allowing the operator to observe the protected object in HD quality. The most complex video analytics algorithms, if they do not replace the system operator, then help him focus his attention on really important events, highlighting them from dozens and hundreds of video channels. The development of special standards for the interaction of ONVIF and PSIA video system components allows us to organize and simplify the joint work of thousands of different models of video cameras, recorders and software. Finally, lenses with high-quality optics and multiple zoom allow you to literally find a needle in a haystack at a distance of hundreds of meters.

As ​​for image quality, everything is really good when the video surveillance system is operating indoors or outdoors with normal operating conditions.

If it is night outside, it is raining and there are natural obstacles in the observation sector in the form of dense thickets (it is clear that there should be a right-of-way to organize unimpeded observation, but, you must admit, this is not always the case), then everything is not so good. Of course, you can organize ideal artificial lighting of the stage, mow down all the vegetation, even cancel the bad weather. True, it is unlikely that you will be able to disperse the clouds every time. But all this can be very difficult, expensive, and sometimes simply impossible. And then unconventional means of observation come to the rescue.

Thermal imagers are often confused with night vision devices.

Meanwhile, these devices are based on completely different physical principles.

A night vision device simply multiplies the light in the visible range reflected from the object of observation, i.e. it needs illumination, even if minimal. A thermal imager, as its name directly indicates, registers the heat emitted by the object of observation. Thus, a thermal imager can work in absolute darkness, and, what is most valuable, the object can even be visually hidden from the observer behind a veil of rain or foliage. This is not an obstacle for a thermal imaging camera.

In video surveillance systems, the task for thermal imaging equipment is even somewhat simplified: it is enough to simply register a change in the surveillance picture and identify a potential intruder in it. In general, a thermal imager is a fairly accurate device for remotely measuring the temperature of an area object. Today, it is an indispensable assistant in many industries and construction. With the help of a modern portable thermal imager, you can quickly and easily determine, for example, the temperature of individual units and assemblies of industrial equipment. Detection of overheated parts allows you to identify faults in advance, without bringing the matter to serious accidents.

In construction, thermal imagers are widely used to control the quality of thermal insulation. Points of heat leakage or, conversely, cold penetration will be clearly visible on the thermal imager screen.
How does a modern thermal imager work?

The general scheme is very similar to a conventional optical video camera. The measured parameter, in our case heat, is recorded by a matrix of semiconductor heat-sensitive elements. If anyone is interested, such an element is called a bolometer.

Under the influence of heat, the electrical resistance of the heat-sensitive element changes and, accordingly, the current flowing through it. Then the signal from each matrix element is transmitted to the electronic processing unit, where a complete image is formed, displayed on the video surveillance system monitor. Each value of the measured temperature is assigned its own color. The color can be selected from a full palette, thus forming a color image, or from shades of gray — then the image will be black and white. As a rule, lighter areas have a higher temperature. It is clear that the color in the image obtained from a thermal imaging camera is in no way related to the real color of the objects. The resolution of the matrix of heat-sensitive elements is relatively small, the most popular formats are 320 x 240 and 640 x 480. The heat flow hits the matrix through the lens, which is not made of glass, which, as is known, does not transmit infrared radiation, but of a much more expensive material, most often germanium. A thermal imager, by the way, is not a cheap thing, an average model can cost 000-15,000. So the matrix of heat-sensitive elements and the lens make up about 90% of the cost of a thermal imaging camera. The output for connecting to a display device for a thermal imaging camera is the same as for a regular optical camera: an analog signal PAL or NTSC. Although today you can already find thermal imaging IP cameras.
As we have already found out, thermal imaging cameras are designed primarily for outdoor surveillance in difficult conditions. But do not think that thermal imagers are used only at night, they can also have a lot of work during the day. In conventional television cameras, color contrast is used as the main feature by which the observer must recognize the target. What happens if a potential intruder is dressed in camouflage and in summer he blends in with the greenery, and in winter with the snow? Observation in the visible range is extremely ineffective here. Thermal imaging cameras do not have such a limitation, and on the monitor a person will be visible as a bright spot against the background of the surrounding area, even if he completely blends in with it and is completely invisible to the naked eye.

Let's move on, thermal radiation passes through the atmosphere more freely than visible light, so smoke, dust and even light fog are no obstacle for a thermal imager. Bright sunlight in the eyes? For a thermal imager, this is not a problem either. And all this works at a very decent distance. Last summer, we conducted field tests of several models of thermal imaging cameras. So, it was possible to determine the movements of a person in conditions of complete darkness and natural interference in the form of greenery at a distance of up to 500 m. This, however, turned out to be somewhat less than the characteristics declared by the manufacturer, but after analyzing the test results, we concluded that the extremely high ambient temperature played a role. Remember how hot it was? According to the test protocol, at midnight the temperature was recorded at almost 30 ° C! Although, you must admit, when you read about this in winter, it does not seem so bad. In our opinion, the deterioration of the results was probably affected by the low thermal contrast of the target, i.e. there is a difference in the temperatures of the person and the surrounding background. In winter the results would most likely be much better.
The unique capabilities of thermal imaging cameras can be successfully used to protect facilities with large open spaces, such as airports, open warehouses, seaports and many others. Where it is very difficult and expensive to organize normal lighting, and weather conditions can bring these efforts to nothing. And, of course, perimeter protection — here in many cases there is simply no alternative to thermal imagers. It is also important that the thermal imager practically does not react to such natural interference as illumination or movement of leaves in the wind. This means that the motion detector analyzing the image from the thermal imaging camera will work much more stably and reliably. Thermal imaging camera manufacturers often offer solutions using two channels. Two cameras are located in one case: a regular one and a thermal one. This allows you to combine and combine the capabilities of both surveillance methods, which further increases the efficiency of the security system.Science and technology do not stand still, new methods and materials are being sought. The cost of the main components of thermal imaging cameras is constantly decreasing, their design is being simplified, and the resolution is increasing. It is worth noting that until relatively recently, such solutions were simply impossible in such a compact design, since heat-sensitive elements required forced cooling. Today, all thermal imaging cameras for video surveillance use matrices based on uncooled bolometers. Optics made of more affordable materials will soon be offered. All this will allow thermal imagers to be used in an even wider range of tasks. Although even now, in many cases, their use is more than justified. After all, as the professionals say? Correct: you can't save on security, it will cost you more.

Thermal imaging network camera AXIS Q1921-E (AXIS)
AXIS Q1921-E Thermal Network Camera is designed for outdoor use, comes with a built-in window heater and is fully prepared for installation and operation in harsh weather conditions. The camera's thermal imaging technology enables detection in complete darkness and in difficult conditions (smoke, fog, dust, heavy haze).
The camera is ideal for 24/7 security surveillance of a selected area or perimeter at sites such as roads, tunnels and airports. Several lens options are available for various applications.
The camera is equipped with motion and sound detection, as well as an alert in case of unauthorized actions.
Supports the H.264 video compression format and has dual-channel audio support. Provides transmission of multiple individually configurable video streams in H.264 and Motion JPEG formats. Uses Power-over-Ethernet (IEEE 802.3af) technology.
Supports the ONVIF standard.

Oculus Ti (Infinity) PTZ camera with built-in thermal imager
Oculus controlled video cameras are specially designed for installation at sites with increased requirements for surveillance system equipment. The camera body is made of durable anodized aluminum and provides reliable protection against accidental mechanical damage or possible acts of vandalism, as well as against the negative impact of an aggressive environment with a high content of oxidizing substances. The cameras can be used at sites with the most difficult operating conditions, such as seaports, railway terminals, large parking lots, etc.The Oculus-Ti series has a built-in thermal imager, which ensures the operation of the surveillance system in difficult visibility conditions. There are several versions of the camera, which differ in the characteristics of the thermal imager. Depending on the requirements of the object, a sensor with a resolution of 160 x 120 or 320 x 240 pixels can be installed in the camera. In addition, there are versions of sensors with different viewing angles — narrow, medium and wide. Depending on the thermal imager modification, the detection zone can be from 100 to 1000 m.

Multifunctional surveillance system AVATAR (PERGAM)
The system allows surveillance in complete darkness, in bad weather and in conditions of parasitic illumination.
The AVATAR system is built on a modular principle. A thermal imager, a video camera and a rotary platform are installed on a high-precision reliable rotary platform. The precision rotary mechanism ensures constant rotation, and in the azimuth plane at any number of turns of 360 º/s. High rotation speed in both planes up to 180º/s allows for an instant response to external events when operating in automatic mode. The minimum rotation speed, starting from 0º/s, ensures smooth rotation of the rotary device in the tracking and automatic target tracking mode. The AVATAR system can operate in conjunction with radars and perimeter alarms.
Depending on the requirements for the observation range and resolution, the thermal imaging module can be equipped with detectors of various formats: 160 x 120, 320 x 240, 384 x 288 and 640 x 512 pixels.
The video camera module is equipped with a ¼ CCD matrix and a 36x optical zoom for use during the day or night.
The AVATAR system fully supports operation in analog or digital IP video surveillance systems.

Portable thermal imagers H-series (FLIR)
The H-series thermal imagers are portable, impact-resistant devices for law enforcement. Infrared cameras create a clear image at night, regardless of weather conditions. With the H-series thermal imagers, security professionals and law enforcement officers can see an intruder even in complete darkness, through smoke and foliage. The thermal imager sees perfectly in thick fog. The H-series thermal imagers are indispensable assistants for foot patrols who guard industrial facilities or state borders, customs officers and law enforcement officers, and other specialists who are faced with the task of covert security surveillance in complete darkness and any weather conditions.

Thermal imager of the C-Allview Thermal (GANZ) series
The thermal imager is designed as an outdoor rotary device that combines an analog camera with a 36x zoom lens and a thermal imaging camera with a resolution of 320 x 240 pixels. The camera can be controlled using GANZ, Pelco-D, Pelco-P and some other protocols, which facilitates its integration into existing video surveillance systems. The camera can be remotely directed in any direction, as well as vertically up or down, which ensures surveillance without blind spots.
The C-Allview Thermal line of thermal imaging cameras has optics with a horizontal viewing angle of 50°, 25° or 12°, which allows you to detect a person at a distance of up to 1200 m. The device has two analog video outputs. One is for an analog camera, and the second is for a thermal imaging camera.