Thermal cameras are used in a variety of situtations. In a search and rescue or surveillance roles, detecting body heat or the heat from a vehicle is the most common use, with the heat source displayed relative to the background using various colour pallettes to accentuate the temperature differences.
Thermal imaging from drones.
When used to inspect building or machinery, a similar technique can be used to see hot spots on a working machine, or thermal leakage from a building, but it is also possible to take the analysis further and record full thermographic data. This allows the operator to review the images after the flight, and get exact absolute temerature readings pixel by pixel, from all frames recorded during the flight.
Industrial drones @ Professional-Multirotors.com:
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