Special Focus: Status Report on Thermal Cameras
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Very often advances in security technology come in small steps or can be described as marginal gains improving existing products. Those small improvements should not be underestimated as they may change a system from underperforming to the status of exceeding the requirements. When I had the chance to experience the performance of one of the first thermal camera systems live years ago, it was clear that this new technology would not be a small improvement but a game-changer.
When we gathered for a life demo in the room of a local integrator, we could see two cameras pointing into the twilight of a November late afternoon. As we had heavy snow on that day, with the best video camera available, we could hardly see anything outside on the street that was farer away than 50 meters. With the thermal camera we could clearly see a man walking his dog in about 250 m distance. Already this demo almost ten years ago perfectly showed the capabilities of thermal cameras. No matter how poor the visibility is because of darkness, fog, rain or snow, with a thermal camera you may spot an object moving towards a perimeter or restricted area, as thermal cameras capture images based on heat radiating and not via visible light.
„Under normal daylight conditions, we can recognize possible hazards most easily using CCTV cameras. But they show weaknesses at night and in adverse weather conditions“, explained a security officer from a major European airport, when asked about thermal cameras and added: „Thermal imaging cameras work very well day and night and even in cases of light fog or smoke, but they also reach their limits during tropical rainstorms. In this case the water acts as a wall which is impermeable to thermal radiation.“
Lower Costs Allow More Options
Already in the early days of thermal cameras they were a very valuable tool for high end security solutions whenever normal camera technology was not enough. In a lot of projects thermal cameras were chosen when there was simply not enough light in remote areas or when there was a need to cover large areas like at borders or large perimeters 24/7. But due to very high prices for thermal cameras, one could easily spend more than 5,000 Euros for a single unit, their prevalence was very limited.
This has radically changed when more and more vendors developed thermal cameras and their price was lowered. At the same time higher resolution cameras with a better performance became available. These days thermal cameras are an option for more security projects and it is worth to look at other advantages they offer. For David Montague, Senior Director Security EMEA at Flir Systems, one of the pioneers in thermal imaging, the level of performance of modern thermal cameras clearly provides advantages over many other technologies, reducing the need for civil works as there are less cameras as opposed to standard CCTV cameras. Further, no additional lighting is needed, reducing cost and having less of a negative impact on the environment. He adds: “In recent years the price for thermal cameras has reduced to a level which has allowed for additional markets to be created. Thereby, offering the best technology solution at an affordable price with significant environmental advantages. When compared to other detection technologies, thermal provides earlier warning with consequent savings on lives and assets. Also in areas with smoke from a fire situation, thermal cameras will be able to equally perform as smoke does not affect the thermal image. This allows the user to stay in better control of the situation, enabling guidance for public address systems, and rescue and evacuation tasks.”
Unlike standard video surveillance cameras equipped with first generation video analytics, thermal cameras are sensitive in their detection abilities and do not raise too many false alarms. The task of thermal cameras used as sensors consists first and foremost of reliably detecting potential intruders. Priority number one is that if someone or something violates the perimeter, then the system has to reliably detect it. Priority number two are low numbers of false alarms. They should always be kept to an absolute minimum to ensure efficiency and with the integration of thermal cameras this is an achievable task. According to Martin Jensen, Global Product Manager Thermal Cameras at Axis Communications, thermal cameras can be used for various applications where accurate detection is crucial. He points out, that from perimeter protection and patient monitoring to ensuring equipment is operating safely, thermal cameras are in use in many different applications. He adds: “Thermal cameras are continuing to grow in popularity due to their ability to detect the nature of a threat and reduce false alarms, saving both time and money for, which cuts the total cost of ownership (TCO). Due to the wider detection range, thermal cameras reduce the need of numerous cameras as even a few of them can cover a whole property.”
For accurate detection, cameras need to be integrated into the operation chain. When a thermal camera detects motion or somebody is crossing a virtual trip wire, an alarm can be triggered via video analytics software. Modern motion detection system can distinguish between movements in different directions. Often only movement in a certain direction is defined as unusual. The software then sends such an event to the video management system and the VMS forwards the event to the security control center. Some thermal cameras do the analytics already on the edge with built-in analytics. The Avigilon H4 thermal camera for example is embedded with self-learning video analytics to provide long-range perimeter protection and leverages thermal technology to operate under challenging conditions while minimizing false alarms. It is designed to detect the presence and movement of people and vehicles in areas with poor visibility, including partly camouflaged scenes, low lighting and even absolute darkness, without the need for additional light sources. The camera easily integrates with Avigilon Control Center video management software, for seamless analytics configuration and alarm notification, helping users to focus on critical events and take decisive action when it‘s needed most. The self-learning video analytics recognizes threats with greater accuracy to help to detect, verify and act faster.
A thermal cameras is no tool to identify individuals but thermal imaging cameras have a big advantage that often is overlooked with regard to data protection. They don‘t show individual features, but only depict „temperature signatures“. Therefore, they can be used in all cases requiring special data protection, as they are not problematic in this regard as compared to CCTV cameras. One example are hospitals where thermal imaging can detect patient incidents – such as falls – that need attention, without invading their privacy by recording their image 24/7.
Calibration and Training
In former times proper calibration of thermal cameras was a complex task, as it actually requires a full cycle of the seasons. The conditions in winter are completely different than in a hot summer and a wet autumn is different from spring. When it comes to calibrating thermal imaging cameras, the most important factors are not, as one might think, the extremely high or low temperatures. The medium temperature range is actually much trickier because there is not such a big difference in temperature between the environment and objects.
Safety and Fire Detection Applications
Increasing safety is another task, thermal cameras can help with. There are applications in harbors for example, where thermal cameras can detect man-overboard situations and can help to find a victim in the shortest possible time so that we can get him out of the water before hypothermia sets in.
Fire detection is the application Hikvision has in mind with the launch of a new thermal bi-spectrum turret camera, which brings enhanced capabilities of indoor fire detection, including an advanced temperature anomaly alarm and visual warning. This new camera supports fire detection using high-quality internal hardware components to capture images using both visible light and infrared light, also called “bi-spectrum” image technology. The bi-spectrum image technology creates a picture-in-picture preview and image fusion, which can capture what caused the alarm and help personnel to check the situation quickly. It monitors through only one channel, reducing bandwidth and simplifying the live preview procedure of switching channels between thermal and optical channels. The camera features a reliable temperature anomaly alarm, which will trigger an alarm once the temperature goes higher than a user-set limit.
Another vendor, Mobotix, works with two directly adjacent lenses, too. Their M16 Thermal aims to complement perimeter protection and fire prevention solutions with this technology. The cameras detect and register objects and people using a thermal signature, even in total darkness at a distance of over 100 meters, safeguard privacy and are also extremely effective in detecting life-threatening heat sources early on. There is a thermal overlay function with image overlay (thermal and optical) to pinpoint the exact location of hotspots like smoldering fires in a visible image.
f.l.t.r. Martin Jensen, Axis Communications, Stefan Li, Hikvision, David Montague, Flir Systems
Flir Commercial Vision Systems B.V.
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