Using Wi-Fi to “see” behind closed doors is easier than anyone thought

The Thought Emporium did something very similar with his Building a Camera That Can See Wifi project. He wasn't able to achieve nearly the same resolution that these researchers at the University of Utah did and so could only use it to identify router locations through walls and at a distance in the surrounding buildings, but he wasn't really trying to either since the project was primarily intended to be a DIY Radio Telescope not a snooping device. The ability to snoop was just a fun side effect. :P

I'm honestly surprised it took this long. I bet drone makers would love this. Among many other "applications".

But despite the widespread transparency, this world would be hard to make sense of. That’s because walls, doors, furniture, and so on all reflect and bend this light as well as transmitting it. So any image would be impossibly smeared with confusing reflections.

But this needn’t be an issue if all you are interested in is the movement of people. Humans also reflect and distort this Wi-Fi light. >The distortion, and the way it moves, would be clearly visible through Wi-Fi eyes, even though the other details would be smeared. This crazy Wi-Fi vision would clearly reveal whether anybody was behind a wall and, if so, whether the person was moving.