> Thermal imaging likewise just does not work the way that people think it does. It doesn't work in cold environments like the Sierra in winter (western or east

> Thermal imaging likewise just does not work the way that people think it does. It doesn't work in cold environments like the Sierra in winter (western or eastern), because people are typically wearing insulated clothing and the entire area around them is a gigantic heat sink. It also doesn't work in very warm environments or in heavily vegetated environments or rocky environments with sunlight -- rocks absorb and re-radiate heat and so do plants. I wonder if there's a specific subset of this problem domain where thermal imaging could be very useful: detecting campfires at night. I think this would address the limitations you mention, primarily due to the extreme temperature difference between the fire and surroundings. Since the night sky has a high absorptance to emittance ratio and thus acts as a thermal sink, the surrounding tree canopy would be cool and increase the contrast more. Of course, fire would have a high contrast with its surroundings even in the visible light range, so perhaps I am overthinking this. One possible advantage of thermal imaging though would be if the convective heat transfer as the hot air moves up could act as a sort of long-range beacon? Possibly not because I know any particles in the air, or water vapor will reflect/obstruct thermal radiation over long distances and prevent it from being seen clearly.