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.

One consideration is that you need to know, in advance, where the sensor is for this approach to work.