How it works
The technology thermal cameras use to measure temperature is important in understanding their advantages and limitations. Thermal cameras are exactly that, cameras. They detect electromagnetic radiation just the same as regular cameras do, the difference is that the spectrum sensed is in the infrared region as opposed to the visual region. This means IR light can reflect, refract, radiate and undergo all the same optical illusions that we experience with visual light.
All surfaces with the exception ‘idea black bodies’ emit thermal radiation as if ‘glowing’ in a colour we can’t see. This glowing can be experienced with hot metals that glow at high temperatures, these materials are emitting EM radiation in such a broad spectrum that it reaches into the visual.
If humans had eyes that could see clearly in the infrared region, it would not be a stretch to believe that humans would be able to see and quantify temperatures remotely. Imagine a world of glowing surfaces, from dull cold rocks to blaring road pavement on a hot day, that light up your surroundings even at night. This, however, is not a reality, so we use falsely coloured representations of the infrared spectrum using thermal cameras.
Applications of infrared thermal photography
The commercial applications of infrared thermal photography come into play when the characteristics of emissivity, thermal radiation and drones are taken advantage of.
Remotely sensing thermal radiation allows you to quantify temperatures very accurately and measure their change both spatially and over time. This advantage is augmented through infra-red aerial drone photography where thermal cameras are mounted on drones. This means that large areas can sense, mapped and even modelled in 3D, removing the perspective limitations of ground-based methods.
Infrared drone aerial photography sometimes utilises differential emissivity of surfaces to identify features. Contrast is employed by Uaviation during applications such as search and rescue, feral animal surveys and fauna population monitoring. In all these applications, the low emissivity of forest structures is in high contrast to the body heat of mammals. Uaviation uses this to count and locate points of interest. The same can be done but in reverse for pipelines leakage detection. The specific heat capacity of water is high, meaning it takes a large about of energy to raise its temperature. Uaviation inspects pipeline corridors to detect differential heating of moist and dry soils.
Visible light has difficulty penetrating suspended elements in the atmosphere such as fog, dust and smoke. The long wavelength of Infrared light allows thermal cameras to penetrate these kinds of obstructions better than visible cameras, revealing objects that are normally obscured. Uaviation’s aerial inspection services track the progress of fire fronts through thick smoke during planned burns, ensuring key operation information gets to firefighters in real time.
Satellite technology has extremely powerful thermal cameras and is used extensively in research to study thermal loading of urban structures. A limitation of satellite technology is the temporal resolution at which these observations can be made. Infrared aerial photography using drones can fly beneath a cloud, take multiple readings a day at any desired resolution.