Applying Thermal Surveillance Cameras
Thermal cameras give surveillance solutions unprecedented detection range.
Thermal cameras continue to make headway into the electronic security space, driven by falling prices and the capability of thermal cameras to feed intelligent video surveillance solutions intrusion detection events virtually free of false alarms. But while thermal has great power, it needs to be installed thoughtfully to ensure operational outcomes are met.
WHEN you’re serious about securing large sites against intrusion, thermal is a wonderful tool. Well installed and commissioned, it’s a tool that offers the ability to detect human or vehicle intrusion over hundreds, even thousands of metres, providing huge depth of field across wide angles of view with comparatively paltry power, installation and network demands. Thermal intrusion events can then be used to alert security staff, drive optical camera pre-sets and set in motion a response chain based on certainties. Especially good, thermal camera performance is not impacted by levels of light, smoke, dust or fog. It’s even possible to discern intruders hiding in bush.
All these strengths make the technology ideal for perimeter defence of massive high value sites like ports, solar farms, power stations, and multifarious industrial and defence applications. But this power can be accessed on smaller sites, too. It’s especially valuable for security managers who need a solution able to provide a virtual single zone of protection for a long boundary backing onto public access space. And thermal works brilliantly when integrated into smaller security and surveillance solutions, where it’s compact data streams provide almost flawless detection of intrusion, especially when installed in concert with a quality analytics application. In smaller applications, thermal is just as useful when you want to drive optical camera pre-sets, initiate recording or drive outputs for external lighting or pre-corded PA announcements.
According to Tom Kinkade of FLIR distributor, Sector, the fundamental operational capabilities of thermal cameras are built around its capacity to produce images outside the visible spectrum by creating image of a subject based on the infrared radiation emitted.
“The benefit is that contrast delivery is totally different to the visible spectrum, highlighting details that could be missed due to lighting, obscuration or camouflage,” Kinkade explains. “In a thermal image, a human target is usually the brightest ‘light source’ in the scene making them visible at far greater distances than in the visible spectrum – it’s a bit like looking at oncoming headlights on a long country road, you can see them from a long way off.”
In Kinkade’s opinion, the perfect applications for thermal cameras are vast – they include but are not limited to security applications.
“There are many scientific and efficiency driven applications for thermal cameras,” he explains. “In the security vertical, we see thermal cameras being used for perimeter surveillance and critical asset monitoring in end use cases, where constant situational awareness is mission-critical. Long-range cooled-core thermal cameras provide outstanding long-range threat assessment capabilities in very large sites such as airports, military bases, seaports and borders.
“We have seen great success in deploying IVA on thermal cameras due to the stability of image contrast, particularly useful in PIDs applications. As a FLIR distributor, our go-to product for perimeter applications is the FC-Series-ID incorporating embedded, rule-driven intrusion detection analytics with best-in-breed thermal imagers. We achieve outstanding performance in autonomously detecting and classifying human and vehicular targets at more than 500m.”
Thermal cameras also have role to play inside.
“Thermal imagers are widely used in retail people counting applications and in the security segment there are some unique cases for indoor deployment,” says Kinkade. “We have had some instances where VIP/celebrity customers want areas on their property monitored for security, but they don’t want identifiable footage to be recorded for privacy reasons. Fire escapes are another novel use case in which thermal imagers may be used to detect the presence of people through smoke.”
When installing thermal cameras, Kinkade says installers should familiarise themselves with the key performance benchmarks that contribute to a quality image.
“These include refresh rates (fps), sensor types (Indium antinomide, Vanadium oxide, amorphous silicon etc.), sensitivity in mK, resolution, lens types and f-numbers,” he explains. “The correct combination of these attributes will determine the quality of thermal image you’re going to produce and the longevity of the device itself.
“When it comes to thermal camera resolution, the gold standard for commercial security applications is a native core resolution of 640 x 512 pixels, coupled with thermal sensitivity of usually less than 35mK. 5 years ago, most applications called for 320 x 240 pixels or similar resolutions, but we don’t see that as much these days. At the top end of the thermal market there is increased uptake of true high definition thermal cameras, however, these devices are generally reserved for military or search and rescue use.”
When it comes to variables like lens focal length, Kinkade says such decisions need to be application specific.
“As a distributor for FLIR Systems we sell many thermal cameras and I can safely say there is no such thing as a single ideal fixed focal length,” he explains. “The FLIR FC-Series-O/ID cameras come in 17 different lens/resolution combinations because sites come in all shapes and sizes.
“It’s also important that installers take time to understand the benefits and limitations of the technology, understand the specifications that will deliver consistently great images and invest in products backed by a reputable and knowledgeable manufacturer of thermal products. Importantly, most thermal cameras from mainstream brands are ONVIF-compliant, so thermal can be used in any application it offers benefits – it’s a natural fit on large sites and lends itself to use in drone monitoring.”
Eric Ho at Bosch Security and Safety Systems says thermal cameras are best used in applications where light sources are close to zero and the distance cameras needs to cover is beyond the reach of IR illuminators.
“Applications includes perimeter protection, tracking of boats on water, surveillance of forested areas prone to fog during certain times of the day/night,” Ho explains. “However, there are some common applications that would benefit from thermal cameras yet typically never consider it – traffic monitoring, for instance. Typically, only optical cameras are used, however, the glare from the headlights can cause over exposure to some cameras. Where highways or roads are not well lit, it can cause a huge difference between the light from the headlight and the surroundings, making over exposure more serious.
“In addition, such low light areas will cause motion blur, which is not good for IVA detection. A thermal camera will not experience any of these problems, allowing IVA to work well. A disadvantage is the lack of colour and other optical details of the vehicle in a thermal image but if the priority is IVA event detection, thermal cameras are a good fit.
“Thermal cameras are also useful for internal applications – manufacturing plants would benefit from using thermal cameras to monitor overheating of equipment, while cold rooms for storage of food stuffs are sometimes quite foggy, so if an optical camera is not ideal, a thermal camera is.”
According to Ho, there are a number of things surveillance system operators should consider when trying to get the best performance from thermal cameras.
“For a start, you need to study and understand the scene 24/7,” Ho explains. “A thermal camera is only good if there is a large enough temperature difference between an object (a person) and the background. For example, on a very hot sunny day, if the floor is made of concrete or metal, the heat generated by the flooring can be close to or higher than a human body. When this happens, the object will not appear to be very visible in a thermal image. A body of water like a lake can reflect heat radiation – when a person walks along it, the person’s heat signature will be reflected on the water surface. To a thermal camera, this may signify it is a person.
“Glass or reflective surfaces also reflect heat radiation, similar to water. If someone walks behind a glass wall, the thermal camera will not be able to detect it. Lastly, dark-coloured objects can absorb heat radiation, so a black object will look hotter at night as it absorbed more radiation from the surroundings during the day. Knowing these limitations helps installers decide how to deploy thermal cameras at the right locations. Something else, thermal cameras do not see through anything (not even paper), a misconception many people have.”
According to Ho, thermal camera resolution has not really improved greatly in the last 5 years.
“The highest resolution for video systems is currently only at 640 x 480 pixels, but compared to 320×480 resolution, it provides more details,” he says. “For a perimeter protection application, you benefit from the higher resolution as it will provide more details and the ability to detect further and combined with IVA, performance is more reliable.
“Bosch is one of the very few manufacturers that implement IVA into thermal cameras. Without IVA, a thermal camera needs to be monitored 24/7 – with IVA, the camera monitors the scene for the customer 24/7 and you can still apply forensic search on the recording to find footage in seconds – that’s especially useful in perimeter security applications.
“When it comes to thermal cameras and drones, this technology is still quite new and there are safety concerns which limit drones flying freely in many applications. Typical drone flight times of less than 30 minutes (non-military grade), are also not practical for many security applications.”
According to John Distelzweig, general manager and vice president of security, FLIR Systems, thermal cameras detect the thermal infrared radiation that is emitted or reflected from all objects and surfaces.
“Since thermal cameras rely solely on IR energy to create an image, they are capable of operating in complete darkness, through smoke, and adverse weather conditions, such as snow and light rain,” Distelzweig explains. “This makes thermal security cameras extremely useful in detecting intruders along perimeters, even more so when combined with video analytics. A person’s body heat will typically stand in contrast with their environment. This makes thermal imaging very effective at detecting humans, particularly at night, when visible cameras have challenges or require additional illumination.
“From a security perspective, operators can quickly spot and track intruders in any light and most weather conditions. In fact, a thermal camera can even see the heat of a person hiding in light foliage or deep shadows created by sunlight. In addition, while a visible camera might cover distances of 50 to 120 metres at night, thermal cameras can reliably detect heat sources at distances up to six times farther, requiring fewer cameras and reducing the total cost of ownership.”
According to Distelzweig, any application involving perimeter intrusion detection can benefit from thermal.
“Thermal imaging has become more affordable and widespread in recent years,” he explains. “Professionals and first-responders who didn’t have access to thermal imaging in the past are now able to benefit from its many uses. In addition, small to medium-sized companies can now afford thermal security cameras, such as the FLIR Saros, that are equipped with cost-effective, miniature thermal cameras.
“This opens the thermal security camera market to such operations at construction sites, car dealerships, public parks, and storage facilities that might have previously considered thermal cameras out of reach. Also, when combined with smart analytics that can classify objects, a thermal camera can greatly reduce false alarms by distinguishing between vehicles or humans, which might pose a threat, and innocuous targets, such as roaming animals.”
According to Distelzweig, the most important consideration for installers is achieving full coverage of the perimeter of interest.
“In addition, for installations with multiple cameras, the fields of view of cameras should overlap in order to remove all dead zones in which a camera cannot see a target head-to-toe,” he explains. “When is comes to internal applications because thermal cameras can see through smoke, they are effective with security systems, such as in banks, that disperse smoke to disorient or deter intruders. Security and law enforcement officials can easily see the whereabouts of intruders using thermal, even in black-out conditions. Thermal cameras are also useful indoors as sensors that can trigger alarms when they detect heat, while also providing visual verification of the presence of intruders.”
When it comes to thermal camera resolution, Distelzweig argues there have been improvements over the last 5 years.
“Arguably, the most significant breakthrough in the last five years has been the development of micro thermal imagers, such as the FLIR Lepton, which is smaller than a U.S. dime (Aussie 5 cent piece),” he says. “The development of Lepton led directly to the FLIR One, a small thermal imager that attaches to the bottom of smartphones. While the resolution of such a small imager may not be large (currently 160 x 120 pixels), the outputs of these imagers—as in the case of the FLIR Saros—can be stitched together to create a larger thermal image. For example, the FLIR Saros contains 2 Lepton imagers that combine to create a thermal image with a resolution of 320 x 120 pixels.”
According to Distelzweig, another installation consideration is focal length.
“When considering focal length, installers need to consider the trade-off between detection distances and the width of the scene,” he says. “Larger focal lengths increase the magnification of objects in the field, while smaller focal lengths present a wider field of view. In most cases, the best practice is to define the minimal requirement for scene width and choose the largest available focal length to meet the width criteria. The FLIR FC-Series O and FC-Series ID cameras offer 17 lens options to optimize the FOV and distances.
“Thermal imaging provides more stark contrast in wider and harsh conditions compared to visible sensors. This allows any video analytic to perform more reliably in complex outdoor situations. All FLIR cameras are ONVIF conformant and certified integrations are completed for all leading VMS platforms. Finally, the FLIR Native API allows 3rd party integrators and VMS companies to develop sophisticated integrations which take advantage of sophisticated alarm and slew to event capabilities.”
Distelzweig’s tip for surveillance system operators in getting the best from thermal is to bear in mind that including a combination of fixed and PTZ thermal cameras with analytics can provide optimal wide area coverage of facilities.
“Fixed cameras positioned along fence lines and borders can initially detect potential intruders crossing their fields of view,” he explains. “With additional functionality provided by FLIR United VMS, for example, the fixed camera can then hand-off a target to a PTZ thermal camera that will lock onto and track the intruder’s movements.
Distelzweig argues drones and thermal cameras are a natural fit for monitoring large, high security sites.
“Yes, absolutely,” he says. “With further integration of radar into perimeter systems and slew-to-cue camera functionality, dispatching a drone equipped with thermal to further investigate intrusions is a great way to improve tracking capabilities. Combine this with the drone system integration of FLIR Cameleon command and control software and you can quickly monitor any security concern from the air.”
Meanwhile, Axis sales engineer, Oshana Jouna says there are 2 main types of thermal cameras available.
“The first is the classic thermal camera – this is used to generate images based on thermal or heat radiation for detection or monitoring purposes,” Jouna explains. “The sensor used in the classic thermal camera detects thermal radiation emitted from objects and people. It is insensitive to light levels, darkness and other challenging conditions. The second is a specialized thermal temperature alarm camera – this is used as a remote surface-temperature measuring device. The technology used in a temperature alarm camera allows the camera to detect the heat radiation and measure the temperature as well.
“A classic thermal camera is generally used to detect people, objects and incidents. It outperforms visual cameras in complete darkness and difficult conditions such as smoke, haze, dust and light fog. As they do not need floodlights, they also reduce light pollution and lower energy consumption. Thermal cameras are typically utilized for security purposes, such as perimeter protection around industrial sites, airports, power plants, and other critical areas. Their detection capabilities also make them a valuable tool, for example, in search and rescue operations.
“Meanwhile, a thermal temperature alarm camera is generally utilized in a wide range of application areas where there is a need for temperature monitoring. One common utilization is to monitor critical electrical equipment, e.g., transformers, electrical sub-stations. The purpose of the camera is to predict failures and locate problem areas. A temperature alarm camera is well suited for predicting failures since it can indicate certain problem areas that are not yet visible to the normal human eyes.”
Jouna says that while thermal cameras are typically used in industrial applications, the potential of the technology is much greater – the cameras don’t just have great catch performance, they can also protect privacy.
“Axis has launched new thermal cameras that are discreet with lower cost making it possible to use thermal cameras in retails and healthcare applications,” he explains. “The new Axis thermal cameras can be used as a sensor to avoid compromising privacy, for example schools and care homes – thermal imaging detects incidents without revealing personal details of the people in the image. Together with analytics, the thermal camera can trigger alerts or alarms in response to patient or resident falls, allowing staff to take immediate action. Thermal cameras can also be used in facilities that store chemicals or liquid products of different viscosity and temperature. This is useful to estimate the content of the silo or containers to ensure that no liquid is leaking.”
Jouna says that when installing a thermal network camera, there are some things to consider.
“To achieve the best results when detecting people, the temperature of the background of the monitored object should be as even as possible, and it should be colder or warmer than a typical person or intruder that may appear in the scene,” he explains. “In this instance, the intruder will stand out from the background. There should be a free line of sight from the camera to the region of interest, without anything disturbing or blocking the view. The scene should have one or a few easy recognizable objects, for example, a chimney against the sky or a building. A chimney in use will be warm, and a building is almost always leaking some indoor heat.
“Make sure that the scene does not contain any tree branches, flags or similar that move in to and out of the scene when it is windy. The camera should be mounted as firmly as possible, and clear and sharp edges should be kept at a distance from the intended scene. A sharp edge just outside the scene may trigger a false motion alarm if the camera sways in the wind and moves the viewed scene over the edge. Since the camera is moving, it will interpret the changed image as movement in the scene, even though nothing but the camera has moved. Thermal cameras with support for electronic image stabilization are less affected by vibration. However, these factors should still be considered when installing a thermal camera, to optimize camera performance.”
Jouna says that when it comes to focal length, this will depend on the application.
“For protecting a large fence perimeter, the ideal focal length is typically 60mm,” he explains. “This will offer an accurate detection range for human at a distance of 1833 metres using a thermal camera with VGA resolution (640 x 480p). The main objective for perimeter protection is to detect a threat or an actual intrusion at the earliest possible stage. In the first line of defense, thermal cameras are deployed. Modern thermal cameras are very sensitive and accurate; they are unrivalled when it comes to detection. With the aid of the edge-based analytics, you greatly reduce the cost for false or nuisance alarms.
“Axis thermal network cameras are well suited for perimeter and area protection, such as virtual fences, providing discreet and cost-effective detection, as well as enhancing building security and emergency management. The built-in intelligence of the camera, together with added video analytics, creates a solution where the video surveillance system automatically performs an analysis of the captured video. Thermal network cameras help distribute this analysis to other cameras in the IP system, leading to improved efficiency and scalability. Generally thermal cameras from the well-known manufactures are integrated with all the common VMS platforms and for the less common VMS platforms ONVIF can be used. We can confidently say thermal cameras are very well integrated with most VMS platforms nowadays.”
According to Jouna, a classic thermal camera is generally not used indoors.
“However, if installed indoors, thermal cameras can be a useful tool for a search-and-rescue operation in cases such as when a building is filled with smoke,” he says. “Normal visual cameras will be unable to see beyond the smoke. However, the thermal cameras will be able to see heat radiation generated by people, thereby, giving visualization of whether anyone is still in the premises or not.
“One other possible application is for supermarkets, that can also be applied to areas with cold storage. Thermal cameras are placed near checkout counters to see if customers have any cold items (chilled or frozen food items) on their body. This way, staff members will be able to detect customers who are trying to shoplift cold items by placing it inside their loose clothing. Thermal cameras will be able to pick up the temperature difference between the cold item and the body.”
Thermal camera focal lengths, angles of view and operational depths of field.
Jouna explains that thermal camera resolution is a product of the nature of thermal sensors.
“Since a thermal camera is detecting light of another wave length than the normal cameras, it needs to have larger pixels,” he says. “Thermal cameras typically use 25 µm or 17µm pixel size sensors. The sensor would have to be too large to have mega pixel resolutions. It would also be very expensive to manufacture with the technology used today. In addition to this, larger sensors would mean larger lenses which would increase the price even more. Therefore, over the last 5 years thermal camera video resolution has not seen big improvements, unlike the visual camera race to the HD resolutions.
“However, newer generation thermal sensors do have higher resolution in bits. Furthermore, recent technologies have improved the contrast of thermal reading. Thermal cameras can detect small differences in temperature. Recent advanced technology implemented in the thermal cameras is the local contrast enhancement. This enhancement helps the camera distinguish objects, such as humans, from the background even when the temperature difference is very small.”
Jouna says there are key considerations with thermal that ensure the best possible performance.
“It is important to take the environmental considerations into account when calculating the detection range,” he explains. “Ideally a thermal camera requires a temperature difference of 2C between the targeted object and the background. The 2 most important environmental factors that affect the image of an object in the camera are absorption and scattering. They reduce the thermal radiation that reaches the camera, thereby reducing the distance at which the camera can detect an object. Scattering has a greater effect on the loss of thermal energy than absorption.
“Water vapor (H2O) and carbon dioxide (CO2) in the air are the primary causes of absorption. During absorption, the heat radiated from the object is absorbed by water vapor and carbon dioxide and loses some of its energy before reaching the camera. The water vapor content of the air affects image quality even in sunny and clear weather, when the water vapor content can be high. When the water vapor content is low, less thermal radiation is absorbed by the water molecules, allowing more thermal radiation to reach the thermal network camera. This results in better image quality compared to a day when the water vapor content is higher.
“When it comes to scattering, the thermal radiation from the object is dispersed when it hits particles in the air. The loss of radiation is directly related to the size and concentration of the particles, droplets or crystals that constitute polluting, condensing or precipitating conditions such as fog, smog, haze, rain or snow.”
Jouna argues that thermal cameras will play a big part in drones related technology and he says this can be broken into 2 parts.
“Firstly, thermal cameras installed onboard drones,” he explains. “We have a number of technology partners already investigating the possibility of integrating thermal cameras with drones especially after the launch of light weight thermal camera from Axis. This including applications where drones are used in inspecting bridges and large buildings.”
According to Jouna, thermal cameras can also detect and track drones.
“Over the past 10 years the popularity and accessibility of drones have increased considerably,” he says. “This will increase the number of accidents and unauthorised operations. We believe thermal cameras with wide angle field of view combined with accurate and reliable analytics will be a great tool to track drones and control visual cameras with high zoom levels and resolution to provide visual images. There are a number of analytics out in the market that are already using thermal cameras in detecting/tracking drones.”
For Cecil Nie, pre-sales product manager, Hikvision Oceania, the fundamental operational capabilities of thermal cameras include behaviour analysis algorithms basing on deep learning, temperature exception alarms and fire detection alarms.
“Perfect applications for thermal cameras include perimeter protection, fire prevention, hunting, etc, but thanks to the capability to detect
fire and smoke, thermal could work effectively for indoor fire prevention in various scenarios including warehouse, super markets,” Nie says.
“Compared with smoke detectors and heat detectors, thermal cameras could trigger pre-alarm before outbreaks of fire, as well as offering visible images for fire source identification. In applications like warehouse fire prevention, thermal cameras could detect temperature change within a far bigger area compared with traditional fire or smoke detectors.”
When it comes to installing thermal cameras, Nie says there are considerations particular to the technology.
“Because thermal cameras are widely used for long-range detection, both the height and angle need to be strictly calculated before installation. Otherwise, thermal may not reach all the targets as designed,” he says. “When it comes to focal length I’d be thinking 7mm for indoor use to cover wide angles and short distances, while 25mm for external uses would reach targets as far away as 300m. In perimeter detection applications 50mm lens thermal camera can easily detect human intrusion from 500m away.
“Resolution is a consideration, too. The resolution of thermal cameras has been improved, with higher resolution up to 640 x 512 pixels offering more details for target identification, while lower resolutions, like 160 x 120 pixels, bring thermal to an affordable level. Care is also required during commissioning. In perimeter applications it’s recommended to undertake calibration with size filtering and pixel size filtering to reduce false alarms and improve alarm event accuracy.”
Nie says he is looking forward to the ongoing development of analytics and deep learning in concert with thermal camera technology.
“It is believed that once the best combination schemes are discovered, the algorithm can be optimized continuously through massive data samples and training, and may show better application effect,” he argues. “Thus, to optimize the existing schemes, improve the user experience, so that thermal cameras can serve more applications and fields. Integration is no problem either with thermal cameras. For example, Hikvision thermal cameras have been integrated with common VMS, including Milestone, Mirasys, Seetec, ONSSI, Axxonsoft, etc. And all our thermal cameras are fully integration with Hikvision recorders and the HikCentral platform.”
One of a number of companies expanding thermal from the mil-spec end of the market, Hanwha Techwin’s newly introduced Wisenet thermal cameras (TNO-4030T,4040T,4041T,4050T,4051T) support 30fps per second with a resolution of 640 x 480 pixels. These Wisenet thermal cameras provide clear image quality and correct the haze of image edges or objects when seen from a long distance, which are prevalent problems in conventional thermal cameras. Users can choose an optimal lens size (13mm, 19mm, 35mm) according to the monitoring environment.
Hanwha says the thermal cameras’ key operational ability is detecting objects in pitch dark environments by capturing infrared radiation from the objects and creating an electric image.
“Because it is not affected by weather condition, it yields meaningful monitoring of objects or people even in extreme weather such as heavy rain or snow or micro dust,” Hanwha says. “For such reasons, thermal cameras are adopted as optimal solution not only for monitoring military border line and outer zones of urban and city area, but also for monitoring forest fires since it can activate alarms when temperature reaches certain point.
“Indoor installation of thermal cameras is also useful in tunnels since it activates rapid responses in the event of power failures or fires, and in rooms where many machines and devices are connected through wires. Airports can also use thermal cameras to monitor human temperature to detect infection of diseases like MERS and influenza.”