[Symmetry]

Using radars with only distance and relative speeds data, no direction at all, to identify equipment has a long history in the military.

https://en.wikipedia.org/wiki/Radar_MASINT#Non-Cooperative_T...

Humans come in greater variety than airplanes but recognition, especially with things like gait analysis, should be quite possible. Now, I'm skeptical that a photo of a person contains enough information to allow for mmWave recognition though, but I'd assume video does.

[dathinab]

Interesting, though it's enough that two independent mmWave radars can re-recognize a person to count as identifiable. No need to involve visual data. Especially if mmWave radars become common place.