3 ms·

Yeah, it can and will be refined, but the major limiting factor is resolution. Wi-Fi radio waves are just too big to get a very clear image.

mvanbaak 9mo ago
for now ...
- XorNot 9mo ago
  No this is fixed by physics. 5ghz waves are about 60mm wavelength. Your resolution limit is about 30mm as a result.
  - NetMageSCW 9mo ago
    There are techniques that can reduce that limit when you have multiple signals, though whether they can be combined with this technique isn’t clear.
  - deleted 9mo ago
    [deleted]
  - jazzyjackson 9mo ago
    Wifi 7 includes 6Ghz band but fair enough
  - anu7df 9mo ago
    Add a nice prior from a photograph, combine multiple measurements and presto you can pick out a person from a crowd with reasonable accuracy. No?
    - accidentallfact 9mo ago
      It applies to the sensor size as well. Such as you need a 3m sensor to get 100px per radian, under ideal circumstances, unless I'm mistaken. (I think I'm not)
notepad0x90 9mo ago
like i mentioned in another comment, do you really need good resolution for gait analysis? You also have people carrying their phones inside the house all the time, so you know what bssid is associated with that coarse movement. and if you have access to their ap/router combo, you can tell what IP that device has and what domains it's been visiting. Let's say you visit a friend in a different city, the same ISP controlling their router, can use your mac, but even if you turn off your wifi or leave your phone in your car, your volume profile and gait can betray you. how you sit, how you lean, how you turn. I'd wager, if 6-10 distinct "points" can be made out and associated with a person, that's all that's needed to uniquely identify that person after enough analysis of their motion, regardless of where they go in the world. Imagine if they're not using one AP, but using your neighbors AP as well, two neighbor APs and your own can triangulate and refine much better.
- kangaroozach 9mo ago
  [flagged]
  - iso1631 9mo ago
    The authorities know their IDs and fully support them
  - chmod775 9mo ago
    > In China cameras use your gait to automatically ticket you for J-walking and automatically deduct funds from your bank account. I’ve read that before at least. China is a huge place with a population larger than the entire western world combined, so I don't doubt something like that could be happening somewhere. Maybe it was a tech demo? However in general that is not a thing. If you pick any of China's megacities and walk down a street it will take you all of 5 seconds to realize how absolutely not a thing that is. Jaywalking is rampant, so obviously there's efforts to crack down on it, but I've yet to see anyone be shy about it around cameras*. * And cameras really are everywhere. Though I suspect a lot are closer to a decorative prop for deterrence than a surveillance tool.
  - pdntspa 9mo ago
Noaidi 9mo ago
6 cm is too big? It’s big enough to get an idea of people moving around. And what about the 5 cm wave of 6G Wi-Fi? But then we can talk about all the millimeterwave signals that are bouncing around everywhere.
- BobbyTables2 9mo ago
  What about 5G cellular? It already supports millimeterwave bands!

mvanbaak 9mo ago

for now ...

XorNot 9mo ago
No this is fixed by physics. 5ghz waves are about 60mm wavelength. Your resolution limit is about 30mm as a result.
- NetMageSCW 9mo ago
  There are techniques that can reduce that limit when you have multiple signals, though whether they can be combined with this technique isn’t clear.
- deleted 9mo ago
  [deleted]
- jazzyjackson 9mo ago
  Wifi 7 includes 6Ghz band but fair enough
- anu7df 9mo ago
  Add a nice prior from a photograph, combine multiple measurements and presto you can pick out a person from a crowd with reasonable accuracy. No?
  - accidentallfact 9mo ago
    It applies to the sensor size as well. Such as you need a 3m sensor to get 100px per radian, under ideal circumstances, unless I'm mistaken. (I think I'm not)

notepad0x90 9mo ago

like i mentioned in another comment, do you really need good resolution for gait analysis? You also have people carrying their phones inside the house all the time, so you know what bssid is associated with that coarse movement. and if you have access to their ap/router combo, you can tell what IP that device has and what domains it's been visiting. Let's say you visit a friend in a different city, the same ISP controlling their router, can use your mac, but even if you turn off your wifi or leave your phone in your car, your volume profile and gait can betray you. how you sit, how you lean, how you turn. I'd wager, if 6-10 distinct "points" can be made out and associated with a person, that's all that's needed to uniquely identify that person after enough analysis of their motion, regardless of where they go in the world. Imagine if they're not using one AP, but using your neighbors AP as well, two neighbor APs and your own can triangulate and refine much better.

kangaroozach 9mo ago
[flagged]
- iso1631 9mo ago
  The authorities know their IDs and fully support them
- chmod775 9mo ago
  > In China cameras use your gait to automatically ticket you for J-walking and automatically deduct funds from your bank account. I’ve read that before at least. China is a huge place with a population larger than the entire western world combined, so I don't doubt something like that could be happening somewhere. Maybe it was a tech demo? However in general that is not a thing. If you pick any of China's megacities and walk down a street it will take you all of 5 seconds to realize how absolutely not a thing that is. Jaywalking is rampant, so obviously there's efforts to crack down on it, but I've yet to see anyone be shy about it around cameras*. * And cameras really are everywhere. Though I suspect a lot are closer to a decorative prop for deterrence than a surveillance tool.
- pdntspa 9mo ago

Noaidi 9mo ago

6 cm is too big? It’s big enough to get an idea of people moving around. And what about the 5 cm wave of 6G Wi-Fi? But then we can talk about all the millimeterwave signals that are bouncing around everywhere.

BobbyTables2 9mo ago
What about 5G cellular? It already supports millimeterwave bands!