Thermal imaging: revolutionizing public safety with DJI drones.

Thermal imaging has become an essential technology, radically transforming approaches to public safety. Faced with the intrinsic limitations of human vision and traditional cameras operating in the visible spectrum, particularly in darkness, through smoke or against camouflaged elements, a new generation of tools offers unprecedented capabilities. Drones equipped with thermal imaging cameras are emerging as a versatile and powerful solution, capable of “seeing” heat and providing crucial information where the human eye is powerless. Major technology players, such as DJI, are playing a leading role in the development and democratization of these advanced systems, providing professionals with ever more effective tools for their critical interventions. This article explores how thermal imaging, embedded in drones, is redefining intervention strategies and significantly improving the efficiency of public safety missions.

Understanding thermal imaging: Seeing the invisible

At the heart of thermal imaging lies a principle that is fundamentally different from that of conventional photography. Rather than capturing the visible light reflected by objects, a thermal camera detects infrared radiation, a form of energy invisible to the naked eye that all bodies emit according to their temperature. The hotter an object, the more infrared radiation it emits. This ability to “see heat” enables thermal imaging cameras to create images even in total darkness, through light smoke, fog or camouflage that would fool a standard camera.

There are two main types of thermal sensor: cooled and uncooled. Cooled sensors, maintained at cryogenic temperatures, offer extreme sensitivity and accuracy, but are costly, bulky, energy-hungry and have a limited lifespan.

In contrast, uncooled thermal sensors operate at room temperature. Although slightly less accurate, they are significantly more compact, lightweight, affordable, consume less power and have a longer service life. These characteristics make them the technology of choice for integration on mobile platforms such as drones, where weight, size and autonomy are major constraints.

Understanding the principle of infrared radiation detection is essential to grasping the power and potential applications of this technology in the security field.

The keys to effective thermal imaging

Obtaining a usable thermal image and accurate temperature measurement does not depend solely on the intrinsic quality of the sensor. Several external factors and technical parameters play a crucial role in the reliability of the information gathered. Thermal accuracy can be affected by the ability of the camera itself to dissipate its own heat, as internal thermal noise can interfere with measurements. Atmospheric conditions are also decisive: humidity, rain, snow, smoke or dust can attenuate infrared radiation and distort readings. Emissivity, which describes a surface’s capacity to emit thermal energy, and reflectivity, its capacity to reflect ambient thermal radiation, are intrinsic properties of the materials observed that greatly influence temperature measurement. A highly reflective object, for example, may reflect heat from a nearby source, making its own temperature difficult to assess. The angle of view and distance from the target are also important parameters; too great a distance dilutes the thermal signal and reduces accuracy.

Beyond temperature measurement, the ability to distinguish details in the thermal image, or spatial resolution, is essential for target identification. Two key concepts come into play: IFOV (Instantaneous Field of View), which represents the smallest detail a single pixel can “see” at a given distance, and GSD (Ground Sample Distance), which translates this resolution into a real dimension on the ground (for example, centimetres per pixel). A smaller IFOV or GSD means better resolution and therefore a more detailed image, enabling shapes to be better distinguished.

To standardize the evaluation of detection performance, the DRI (Detection, Recognition, Identification) concept is widely used.

Detection is the maximum distance at which an object becomes visible as a distinct heat source.

Recognition is the distance at which the object (human, vehicle, animal) can be classified.

Identification is the distance at which finer details can be discerned (type of vehicle, armed or unarmed person).

Understanding these DRI concepts, coupled with IFOV and GSD, enables us to estimate the optimum operational distance for a given mission, ensuring effective thermal detection, target recognition and thermal identification.

DJI thermal drones: High-performance tools for professionals

DJI has established itself as an undisputed leader in the professional drone landscape dedicated to public safety, thanks in particular to its range of solutions incorporating advanced thermal imaging capabilities. These platforms combine the mobility and flexibility of drones with the power of infrared detection, offering responders tools adapted to a multitude of critical scenarios. Among the flagship models, the DJI Mavic 3T (M3T) stands out for its compactness and ease of deployment, incorporating a thermal camera with 640×512 pixel resolution, ideal for rapid reconnaissance. For missions requiring greater versatility and robustness, the DJI Matrice 30T (M30T) offers similar thermal performance but in a more durable, weather-resistant platform, also featuring a powerful zoom on its visible camera.

For operations requiring greater range and capabilities, the Matrice 350 RTK series can be equipped with Zenmuse H20T or H20N pods. The H20T combines a 640×512 thermal camera with a powerful optical zoom and laser rangefinder, while the H20N takes night-time capabilities a step further by combining two thermal sensors (one wide-angle and one telephoto with up to 32x thermal zoom) with visible sensors optimized for low light. These different DJI thermal cameras share cutting-edge technical specifications, such as a pixel size of 12 μm and IFOV (Instantaneous Field of View) values optimized for detection at different distances (for example, 1.319 mrad for the M3T/M30T, and up to 0.270 mrad for the H20N’s thermal zoom), enabling precise target identification.

Beyond the hardware, DJI offers the DJI Thermal Analysis Tool software ecosystem, a powerful tool for a posteriori analysis of collected thermal images and data, extracting precise temperature measurements and generating detailed reports, thus completing the operational chain from capture in the field to analysis in the office.

Revolutionary applications in public safety

The true value of drones equipped with thermal imaging is revealed in the diversity and impact of their applications in the field. These technologies offer new capabilities and significantly improve operational efficiency in several critical areas of public safety.

Fire fighting: Seeing through smoke

For fire-fighters, drone-borne thermal imaging is a revolution. During urban or industrial fires, it can pierce through thick smoke to pinpoint the location of main fires or “hot spots”, assess the structural integrity of buildings by detecting areas of thermal weakness, and guide intervention teams on the ground by providing them with an invaluable tactical overview. In the context of forest fires, thermal drones are essential for monitoring edges, detecting latent reignitions invisible to the naked eye, mapping the true extent of the disaster and optimizing resource allocation.

Specific functionalities such as different color palettes (suitable for penetrating smoke or identifying specific thermal signatures), isotherms (which specifically color a temperature range, useful for locating human bodies for example) and precise remote temperature measurement are major assets for civil security and fire-fighting teams.

Policing: Surveillance and discreet intervention

Police and gendarmerie forces also benefit greatly from thermal drones for their surveillance and intervention missions. The ability to operate day and night, with complete discretion, enables effective surveillance of large areas, sensitive sites or major events. Thermal imagery excels at locating suspects attempting to hide in darkness, vegetation or even under certain types of light camouflage. It also facilitates the tracking of fleeing vehicles, thanks to the thermal signature left by the engine and tires.

The powerful thermal zoom, available on certain nacelles such as the H20N, enables details to be observed at great distance without being detected, while isotherms can be configured to automatically alert operators to the presence of a heat signature corresponding to a person. These tools enhance the effectiveness of unobtrusive surveillance and improve the safety of operatives during interventions.

Search and Rescue (SAR): Saving lives

In search and rescue (SAR) operations, every minute counts. Thermal drones have become indispensable allies in speeding up victim location. Whether it’s finding a person missing in the forest at night, a hiker lost in the mountains, or survivors after a natural disaster (earthquake, flood, avalanche), the thermal camera can detect body heat even in conditions of zero visibility or through dense vegetation.

This enables civil protection teams and rescuers to concentrate their efforts on the most likely areas, considerably reducing search time and increasing the chances of survival. The SAR drone equipped with a thermal camera offers rapid coverage of vast areas, often difficult to access by land.

Industrial safety: Preventing risks

Beyond emergency missions, drone thermal imaging has valuable applications in industrial safety and predictive maintenance. It can be used to quickly and safely inspect extensive or hard-to-reach infrastructures, such as high-voltage power lines, solar panel farms, pipelines, or the facades of large buildings.

The thermal camera can detect anomalies invisible to the naked eye, such as overheated electrical components, insulation faults, fluid or gas leaks, or moisture ingress. This early thermal inspection capability helps to identify potential risks before they lead to costly breakdowns, accidents or service interruptions, thus introducing true predictive maintenance and improving the overall monitoring of industrial sites.

Good practices and precautions

To get the most out of thermal drones, and ensure reliable data and long equipment life, it’s essential to adopt certain good practices and take specific precautions. The choice of equipment should first and foremost be guided by mission requirements: a compact, portable model like the Mavic 3T will be preferred for rapid deployments and smaller areas, while a more robust platform like the Matrice 350 RTK with an H20N gondola will be needed for long-term missions, requiring maximum range and thermal sensitivity.

Understanding the inherent limitations of the technology and the environmental factors that can influence measurements, such as distance, humidity or surface reflectivity, is crucial to correctly interpreting thermal images.

Maintenance of the thermal sensor itself requires particular attention. It is essential to avoid exposing the thermal camera lens to intense energy sources such as direct sunlight, lava or laser beams.

Such exposure can cause irreversible damage to the sensor, manifesting itself in permanent artifacts on images (“sun burn” phenomenon). Most DJI drones incorporate a software protection function that automatically closes the infrared shutter if intense sunlight is detected, but vigilance is still called for.

Finally, mastering the various software functions is essential for optimizing the use of the thermal camera: knowing how to choose the color palette best suited to the scenario (for example, “White Hot” or “Black Hot” for searching for people, “Iron Red” for detecting hot spots in fires), adjusting the gain mode (High Gain for precision, Low Gain for a wider temperature range), regularly performing a calibration (FFC – Flat-Field Correction) to optimize image quality, and making judicious use of the digital zoom or Link Zoom, which synchronizes the zoom of the visible and thermal cameras.

Adhering to these best practices in the use and maintenance of the thermal sensor guarantees safer operations and more reliable results.

Conclusion: Thermal imaging, an indispensable asset for tomorrow’s security

Ultimately, the integration of thermal imaging on drones represents much more than just a technological evolution; it’s a paradigm shift for public safety players. The ability to see beyond the limits of human vision, day or night, through smoke or camouflage, gives responders a decisive advantage in the field. Whether it’s to control a fire, search for a missing person, monitor a sensitive area or prevent an industrial hazard, the benefits are tangible: precious time saved, better allocation of resources, reduced risks for the teams involved and, ultimately, greater operational efficiency to protect people and property.

The constant advances offered by manufacturers like DJI, with more sensitive sensors, more autonomous platforms and more powerful analysis software, only serve to reinforce the key role of this technology. The future of public safety will undoubtedly be written with the ever-greater integration of thermal imaging, which is asserting itself day after day as an indispensable asset in facing the complex challenges of our time and guaranteeing a safer future. Innovation in this field continues to push back the boundaries, promising even more effective tools for those who watch over our safety.