Summary for those one the run: “umbrella”.
Long story: if you are walking somewhere at night and expect a drone operator with thermal vision to try finding you, have the biggest umbrella that you can get.
Since it’s not in contact with your body, it will be at the temperature of the environment. It will catch the heat radiated by your body and re-emit only a tiny fraction, shedding most heat to air via convection.
Be aware. Metallic umbrellas may (or may not) make you looke like a black hole walking around. This may not be desirable.
If your umbrella is wet, that’s even better.
Note: thermal vision and NIR (near infrared, requires a NIR light source, used by some security cameras) are not the same thing - for NIR, principles of visual camouflage apply. Also, not all night vision is thermal, some night vision devices use light amplification.
Good point. If it’s a drone, the observer is in the upper hemisphere. Covering the entire upper hemisphere is unpractical, but covering a good portion of it can be done.
Then comes a dilemma: people emit considerably both with their head and face, and with their feet.
Covering the head will expose the feet, so maybe ghillie trousers to complement the umbrella? :D
Depending on time of day, the difference in radiance/ emittance is pretty substantial. If air/ environment substantially cooler/ warmer than the individual, this could make something like a suit irrelevant. This might depend more on the sensor (integrating vesus non-integrating, cooled array versus non-cooled).
And then of course the fact that these sensing systems are also regularly paired with other wavebands (b, g, r, nir, ir, mir, etc). It mean its dirt cheap to couple a rgb/ ir sensing system to a thermal system, considering the thermal system will always be 10-100x as expensive as the rgb/ ir system.
I’m all for finding ways to beat these things, but its not clear to me this is the path towards that. Something I’ve wondered about is maybe using these MIR LED’s that have come out to see if you can get the wratten filter to pop, then use a laser system to saturate the detector. Its not clear to me that you can effectively camouflage when its a multiband sensing system. But maybe you can find the detectors and blast them with enough light they can’t see shit.
All good points. And I haven’t played with a multitude of sensors. The only cooled sensor I will have anytime soon is my uncooled sensor + liquid gas evaporating.
Coincidentally, as another experiment, I tried a fast flavour of thermite to get solar protection triggered on my camera (if solar protection is triggered, this particular product goes into shutdown). Sadly, I could not trigger it. With more than a matchbox full of thermite, maybe I would, but at an impractically close distance. I did however achieve my solar charging controller turning on, and starting to charge batteries off the light produced from thermite. Not for very long, about 5 seconds. :)
Lasers of an appropriate wavelength, generally speaking, should work. A laser within the transmittance curve of germanium would get into a thermal camera with fairly good certainty. But lasers cost so much that an interceptor drone with a net gun is likely cheaper. :)
In a military context, if one wants soft defense, one might point a microwave beam at the drone to mess with its onboard electronics, but this also requires ridiculous amounts of power (at least several kilowatts) and has limited range, and in a civilian context, there may not be adequate warning of a drone being present, unless one also carries a thermal camera (then it shines like star).