Hiding from infrared cameras

I saw one of those sick videos of US soldiers shooting at “terrorists” from far away, and following a some single person for a while and following him dropping bombs and eventually killing him… Anyway, the camera they used seemed to be just using the IR spectrum, though I may be wrong. I’m wondering how much cover, and of what type someone would need to hide from such IR cameras. Would covering one’s self with mud like in Alien vs Predator actually work? I wonder what the range of sensitivity is for IR cameras.

No, because the mud would quickly heat up and start radiating heat just like the skin does. If you prevent the person from shedding heat, they quickly die or become incapacitated from overheating/exhaustion.

It has to go somewhere. I guess some kind suit with cooled external surfaces is possible, but it would still be necessary to dump the heat somewhere - so it would need an umbilical or some such.

is there any reason for putting especially much thought into hiding from IR cameras? Is nighttime IR tracking by snipers much scarier than daytime optical tracking by these same snipers? Or is hiding from optical tracking during the day using camouflage inherently easier than hiding at night from IR scopes?

Mythbusters tried this. The only thing that worked was a pane of glass.

More specifically, they tried to outwit a security system with infrared sensor, and first tested various camouflage in front of an IR camera. Mud didn’t work well, neither did a goofy costume, but a bed-sheet worked (held loosley in front, not wrapped tightly).

Makes running away difficult, though.

The other question is how the camera or security sensor are calibrated: the former might show a narrower band than the latter uses.

The bed-sheet was used against an ultrasonic detector, not an infra-red detector.

Was the Mythbusters attempt against a true IR imager or a PIR security device? A PIR simply looks for alternating signal from a sensor that is evidence of something moving across its field of view. It has a comb of baffles that mean that when you walk past you alternately are detected and not, hence the alternating output. Very very simple. No image.

For a deep IR imager that sees essentially heat, you are going to have to keep whatever it sees as cool as the surrounds to avoid detection. Or radiating the same amount of energy as the surrounds. Which is a little bit different. The emissivity of a highly polished surface can be very low. Aluminised mylar could cut your radiation down very significantly, even if the mylar is at body heat. You now stand out like a sore thumb in visible light and near IR, especially if the sniper has an IR illuminator. So you don’t necessarily win.

As observed above, you can’t simply make an insulating suit, the heat has to go somewhere, but a cape made of layers that kept the outer surface of the cape cold would probably help a great deal. Camouflage patterns that work in the IR (patterns of different emissivity material) would help break it up more, but it has to be much the same temperature as the background.

Both, but the bit I’m thinking of was a FLIR camera. Can’t find a clip.

They are not mutually exclusive.

The snipers could use IR cameras during the day if they want to.