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Everything you NEED to know about thermal drones

Drones equipped with thermal cameras have saved countless lives during search and rescue efforts by covering large areas quicker than grounds teams and detecting a heat source of a missing person.

Last updated on

November 8, 2022


    Drones equipped with thermal cameras have saved countless lives during search and rescue efforts by covering large areas quicker than grounds teams and detecting a heat source of a missing person.

    They have also enabled police forces to locate offenders and uncover important evidence that would have gone undetected without an aerial view, as well as pinpointing the source of a developing ammonia cloud during a dangerous chemical leak.

    With the release of the DJI Mavic 3T back in September, we take a dive deep into thermal imaging and how thermal imaging drones are changing the face of critical missions.

    Thermal drones in action


    On March 20, 2022, firefighters battling a grassland wildfire in Cleburn, Texas, deployed a DJI Matrice 30T to provide extensive situational awareness of the spreading fire. Thermal drones could see through the thick smoke and safely direct ground crews to the hotspots. They were able to contain the blaze within four hours and keep it away from nearby homes.

    Massive wildfires engulfed Ukraine’s Chornobyl Exclusion Zone in 2020. Despite the dense plumes of smoke that significantly hampered their visibility, 2 DJI Mavic 2 Enterprise Duals were dispatched and enabled firefighters to navigate to hot areas.

    Drones were critical in the search for missing people in Vietnam during monsoon-related floods and landslides. The UAVs (DJI Matrice 300 RTK and DJI Mavic 2 Enterprise Dual) performed three primary functions: they shot high-quality aerial imagery, used thermal sensors to search for heat signatures, and captured telemetry data for 3D models of the area.

    Argentina’s oil refineries use thermographic imaging drones to detect the relative energy generated in various segments of their plant architecture. Using thermal drones such as the DJI Matrice 300 allows inspectors to gain a clear picture of the condition of the equipment without forcing staff to approach potentially hazardous sections.

    During a chemical leak in Sarasota, Florida, thermal drones collected aerial recon footage. The UAVs enabled personnel to pinpoint the source of the problem amid a developing ammonia cloud.

    Thermal UAVs assisted firefighters in Bentonville, Arkansas, in monitoring the temperature of a hazardous difluoroethane tank while a nearby industrial facility burned. Deploying drones like the DJI Mavic 3T allowed personnel to carefully cool the tank and keep it from exploding.

    Thermal drones such as the DJI M3EA assist farmers in scanning fields for baby deer that would otherwise be camouflaged among the long grass. The baby deer can return to safety, and the farmers can plough their fields without jeopardising the fawns’ lives.

    These are only a few examples of how thermal drone technology has positively impacted traditionally tricky situations. They highlight how critical it is to have the correct payload for the job. UAVs outfitted with thermal imaging systems are already making an impact, and the technology is constantly advancing.


    How does thermal imaging work?

    When examining the present and future of thermal imaging drone technology, it is worthwhile to delve into the technical concepts that enable thermal cameras to function. Understanding how thermal imaging equipment works can lead to more efficient use of the technology and innovative deployment strategies for thermal drones.

    Heat, commonly known as infrared radiation (IR), is just atoms vibrating. Objects emit a heat signature based on how fast their atoms move – the more rapidly the particles move, the hotter the object. Thermography is the study of these heat signatures and the application of thermal imagery knowledge. 

    Humans can feel heat but cannot see infrared radiation. Why is this the case? Because this radiation has an electromagnetic wavelength that the human eye cannot perceive. Thermal cameras turn infrared signatures into something we can see.

    How do thermal cameras work?

    Thermal cameras combine specialised lenses that detect infrared frequencies and thermal sensors and image processors to present the results on a visual display. When an infrared camera is mounted on a drone, it is usually mounted on a gimbal, stabilising the image and allowing the lens to rotate 360 degrees.

    Thermal sensors within these advanced cameras, known technically as microbolometers, have significantly improved in recent years. Today’s solutions do not require the specialised cooling materials employed in the past, making them far more accessible.

    Drone thermal cameras can detect many objects, but there are a few exceptions, e.g. highly polished, shiny, and reflective items do not absorb much heat as they have low emissivity. These are difficult to detect using thermal cameras. High emissivity objects, such as wood, concrete, and even people, are simple to scan.


    How to read and process thermal images

    Once drones’ IR cameras capture thermal data, it is displayed on a screen as a conventional image for operators to review.

    Users of thermal imaging software can modify the colour palette to display the area’s heat. Each view helps extract details from the image and includes the following: 

    White Hot: Hotter objects appear lighter, while colder ones appear darker. 

    Black Hot: The reverse of hot white, with hotter objects becoming darker.

    Temperature corresponds to hues, with warm colours representing heat. 

    Of course, those three alternatives are only the beginning. Modern thermal cameras provide a more comprehensive range of views; the Zenmuse H20T has 12 distinct colour palettes.

    The format in which imagery is recorded and stored is also determined by the type of thermal camera employed. While lower-cost systems record images as simple image files, more advanced solutions include thermographic data and temperature readings, as well as GPS tags. The DJI Thermal Analysis Tool can examine the thermographic data in more detail.


    How to look after and maintain a thermal camera

    Before you begin using your thermal drone, it’s crucial to understand how thermal sensors are frequently damaged and how to avoid this. While DJI products are famed for their high build quality and longevity, temperature sensors, by definition, are exact, finely-tuned instruments that must be used with caution and consideration. Improper use can permanently harm the thermal sensors, resulting in abnormalities in the data you capture. 

    Here are some examples of thermal images captured by DJI M30Ts where thermal sensors have been damaged by direct sunshine exposure:

    Remember: DO NOT expose the thermal camera lenses to powerful energy sources such as the sun, lava, or a laser beam to avoid this happening to your thermal drone’s sensor. Otherwise, the camera sensor could be damaged permanently.

    How to take accurate thermal measurements

    Even highly effective thermal cameras must contend with several environmental conditions that might make taking an accurate surface temperature reading tricky. These include meteorological conditions such as excessive heat, humidity, clouds, rain, or snowfall, which might compromise the thermal camera’s accuracy. Thermal cameras also struggle with glass because the reflective glass might absorb heat from the sun, the ground, or another object. 

    The surface coating of an object could impact a thermal drone’s capacity to take temperature readings. Corrosion or a fresh coat of paint can alter an object’s relative temperature reading. The sun’s close location can also affect items made of the same material to appear differently in a thermal camera.

    To use a thermal camera effectively, keep the following points in mind:

    • Atmospheric conditions
    • The presence of smoke, dust, and debris
    • Emissivity
    • Transparency
    • Reflectivity
    • Time of day
    • Viewing angle
    • Paint on an object
    • Distance from target
    • Amount of thermal energy
    • Surface roughness or smoothness

    Keeping these characteristics in mind makes it possible to represent an object’s or landscape’s thermal properties accurately.

    Advanced camera considerations

    High resolution and more colour display options are only two of the benefits of high-tech thermal imaging camera systems. The most innovative capabilities will surpass these gradual changes in today’s fast-paced technological development. 

    These powerful new capabilities to consider include:

    • Dual camera drone payload options: Drones with advanced thermal imaging equipment can take multiple photographs simultaneously. Hybrid thermal payloads combine a traditional imaging system with an infrared camera.
    • User-customised isothermal settings: Using a thermal drone control panel, users can set isotherms and custom temperature settings. For example, users looking for potential fires can ask the camera to display images that contain high-temperature zones automatically.
    • Next-generation thermal imaging software: The software used to interpret IR images is evolving, delivering new abilities such as temperature tracking for specific objects, real-time heat updates, an overlay of visible-light and IR images and more.

    Backed with ever-evolving thermal drone technology, organisations can expand how they use these UAVs. Mission specifications that might have been unthinkable just a few years ago are worth revisiting as thermal imaging becomes more precise, versatile, and affordable.


    What payloads to use for thermal imaging

    Choosing a thermal imaging payload for a drone is a matter of matching the equipment’s capabilities with the organisation’s use case. Various variables affect how well a camera system performs in the field and how much you can expect to pay. These include:

    • Field of view (FOV): This measures how much a camera can take in a visual image.
    • Weather resistance: This measures an electrical enclosure’s resilience to the elements, including moisture from rain and fog, and is measured in ingress protection (IP).
    • Spectral band: The spectral band is the electromagnetic range detectable by the camera’s IR sensor.
    • Thermal sensitivity: This metric denotes the degree to which a sensor can measure differences in relative temperature and is also called noise equivalent differential temperature (NEDT).
    • Image resolution: Rather than how big an area the camera captures, this reflects how many pixels go into the digital image generated, which determines the level of detail. 

    You can choose a thermal camera payload to suit your needs based on the type of job you need a drone for and the conditions in which you intend to operate the thermal UAV. For example, models from the Zenmuse H20 series are among the most capable payloads on the market.

    The Zenmuse H20T is a triple-sensor drone camera with a 20MP zoom camera, a 12MP wide camera, and a 1200m laser rangefinder. The Zenmuse H20T also includes a radiometric thermal camera with a resolution of 640 x 512px. The camera creates R-JPEG files with integrated temperature data, allowing for additional analysis. 

    The thermal camera records at 30fps and has a high level of thermal sensitivity. The payload, which features a wide range of colour palettes, customised isotherms, and temperature alerts, allows operators to choose between high-gain and low-gain modes, depending on whether they require a more comprehensive temperature range or increased sensitivity.

    The Zenmuse H20N payload is similar to the H20T but has more sophisticated functions related to its mission profile as a night vision camera. The payload’s starlight night vision camera can zoom in in time with the thermal camera, displaying the results in a split screen format. 

    With two thermal cameras capable of x2 and x8 zoom, the device has an x32 zoom capability. Users can zoom in on a thermal image to analyse hotspots or other temperature abnormalities.

    Drones can intervene in various situations using sophisticated camera payloads, such as searching for missing people at night, scanning for suspected fires, performing electrical inspections, or any other possible application.


    Thermal drone applications: now and in the future

    Thermal drones can now perform more functions than in the past, thanks to more precise sensors and better price points that offer new options. This process of discovery and expansion is ongoing, with new use cases constantly emerging.

    If your organisation engages in any of the following activities, a thermal drone may be the perfect piece of technology for your needs:

    • Firefighting: One of the most common uses of thermal drones is as firefighting tools. Heat mapping from the air allows firefighters to get ahead of risk factors. When working inside structures, it’s possible to map out potential points of failure, while in wildfire scenarios, drones can help crews intercept fires’ progress in the open.
    • Search and rescue: Thermal drones can help rescuers in various disasters, not just fires. Thermal drones can help teams discover missing victims in the aftermath of disasters like floods, landslides, earthquakes, tornadoes, and hurricanes, even at night. These thermal UAVs can also locate people who have become lost in the wilderness.
    • Aerial utility and mine drone inspections: Drones make it easier to inspect utility infrastructure, from plants and solar panel installations to long-distance power cables. No matter how vast a plant or mine is, drones can fly over it and take readings. Using thermal cameras in conjunction with conventional imaging allows crews to keep an eye out for potential failure risks in novel ways, as well as monitor the status of thermal panels.
    • Advanced agriculture: Monitoring crops and grazing herds from the air is an underutilised application for drones. Thermal imaging allows farmers to evaluate field heat exposure and track animals at night. Ongoing attempts to improve farming efficiency through technology perfectly match drone deployment.

    Thermal drone use has expanded rapidly beyond public safety functions and into efficiency-enhancing applications in utilities and agriculture. This demonstrates that users, both professionals and hobbyists, are continuously thinking of new applications for thermal drones. 

    The sky is the limit as thermal camera payloads become increasingly advanced while remaining inexpensive. Suppose your company has to conduct rigorous airborne inspections of difficult-to-reach infrastructure or keep an eye on workers or assets at night or in adverse weather. In that case, a thermal drone could be beneficial.


    What are the best thermal drones?

    While the camera payload you choose is vital for thermal drone performance, so is the commercial drone chassis you select. The appropriate drone body will provide the speed, manoeuvrability, service range, battery life, and other characteristics that will define your new thermal drone’s duties. 

    Here are a few market-leading commercial drones to consider for your thermal deployment.

    DJI Mavic 3 Enterprise Advanced

    The M3EA is an extraordinarily compact and lightweight drone with a plethora of powerful capabilities. It has an inbuilt 640 x 512 thermal heat sensor with x28 digital zoom and a frame rate of 30hz. Integrated with a range of accessories to boost operations, including RTK Module for centimetre-level positioning, and high volume loud-speaker – especially suited to public safety and search and rescue missions.

    DJI Matrice 30T

    The M30T is a rugged drone built to stand up to the elements and designed to be highly portable despite its impressive sensor payload. The M30 T’s system is extremely sophisticated, with a 7-inch widescreen display on the dual-stick control system optimised for enterprise drone pilot use.


    DJI Matrice 300 RTK

    The M300 RTK is capable of carrying up to three payloads at the same time. The M300 RKT can be outfitted with one upward and two downward gimbals. To assist a drone operator in navigating potential obstructions, the M300 RTK has a revolutionary display system that incorporates additional information onto the primary screen. Users can gather new quantities of high-resolution thermal data by fitting the M300 RTK with a Zenmuse H20T or H20N as one of its payloads.


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