The truth is plainly obvious from all those televised high-speed chases in Los Angeles where the chase takes place at night so the Forward Looking Infrared camera on the police helicopter gets to show the Cool High Tech imagery. Steam is not good for IR either, but any light fog (which is usually cool) could be penetrable to an extent. Anyone looking at a sheet of glass with a thermal imager is more likely to see their own reflection. In fact an infrared camera meant for thermal imaging (as opposed to near-infrared), the kind most often seen on TV and movies, cannot even see through a sheet of regular glass that's perfectly clear to anyone using the Mark One Eyeball (this is the effect greenhouses are based on). Walls are generally supposed to stop heat from getting through them, which is why they are insulated. Heat simply doesn't go through walls in such a way to form a picture. Sadly, real thermal imaging infrared cameras don't work like that at all. It's incredibly convenient for the good guys being able to make out what's happening inside the building. Whenever someone calls for the infrared camera on TV shows and film these days, either the handheld version or one mounted on Spy Satellites, the device will have amazing qualities, chief among them being able to see through walls.

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