Thermal imaging is an expensive business. It isn't just the camera technology but the brains that go behind it. It has little current purpose for hobby UAV flyers, unless you're a wealthy wildlife enthusiast.
The current crop of UAV based platforms is, however, starting to bear fruit. DJI, the market leader has recently launched the XT range of thermal camera for its high end Inspire, Matrice 100 and Matrice 600 multi-rotors.
Using a thermal camers brings alive the many aspects of aerial photography that daylight sensors don't capture. Take a look at the image below. It was shot from an altitude of around 150 feet. You can see the collection of disused outbuildings showing up as white in the image. This is due to the amount of thermal energy being reflected from the mid afternoon sun.
The image appears to resemble a classic greyscale image. It was shot in 'white hot mode' using a FLIR TAU2 336 camera. Although useful, it doesn't provide a great deal of detail. Now look at a similar image taken with the camera in 'rainbow mode':
You can see that the ground temperature variations come alive with the cooler portions of the image showing up as blue and the warmer areas showing as red to yellow. You can also see better definition for the areas affected by shadow. This is the key capability of a TAU2 camera. It can present images in 13 different colour palettes. It can also use a function known as isotherm and delta t, which enables fine tuning of the sensor to highlight specific temperature ranges.
This kind of capability comes at a steep price but is likely to challenge manned thermal imaging platforms in the coming years.