I remember seeing a (dead tree) newspaper article a few years ago about the police using sat images to detect potential cannabis plantages by the heat radiating from the building.
Sorry, can't seem to find it on the net after a quick DDG
Yes, that would make sense because lots of grow lights can cause significant heat. I don't think heat technology could see individual people through a roof though.
Sorry, can't seem to find it on the net after a quick DDG