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Locating Stealth Fighters with Cheap Cameras Without Using AI or Radar [video]
- maxglute 1y agoIf you spam a dense enough network of connected sensors you can detect anything.
- djoldman 1y ago* Locating moving objects that could be anything that can move at a speed, with Cheap Cameras Without Using AI or Radar
- mapt 1y agoAerodynamics & engineering dictates that not many things can move at the speed/agility of a stealth fighter. If you've got a radar system already in place, "Stealth" is just the ones that don't also pop up on the radar.
- robocat 1y agoPresumably scattered radar receivers can detect faint reflections using similar correlation. Is there a background microwave radiation at shorter wavelengths that could be made into a camera that could see through clouds too? microwave is too long wavelength to make a small camera.
- dingaling 1y ago> Presumably scattered radar receivers can detect faint reflections using similar correlation. Yes, multistatic radars are already in service. An advance on the concept is that the active transmitter can be placed outside anticipated weapons range and those within range are merely passive receivers. There have been proposals to build such systems that use 'oblivious' transmitter sources such as commercial radio broadcasts.
- mikewarot 1y agoThere was a project to extend/enhance the Kraken multi-SDR system that got yanked from GitHub, etc, because it tripped over ITAR in that it enabled passive radar. ITAR assumes the US leads the world in technology, and actively prevents us from catching up if we don't.
- ajross 1y agoLocating civilian, friendly and radar-visible aircraft is a solved problem though. So the distinction is only a matter of subtraction. No, in fact this kind of technique absolutely puts a hard limit on the value of "stealth" devices, which are purpose-designed to evade a very specific technology that was a warfare-changing innovation in the 1940's but is now pretty cheaply replaceable by consumer junk. The days of large manned aircraft are very much numbered, and armies that fail to see that are armies that are destined to lose.
- throwaway81523 1y agoIf it's a clear day and the bottom of the airplane is painted blue, it could blend in with the sky. For that matter, didn't Wonder Woman have a transparent airplane? Aha, better yet, it was invisible! https://dc.fandom.com/wiki/Wonder_Woman%27s_Invisible_Plane https://dc.fandom.com/wiki/Wonder_Woman%27s_Invisible_Plane
- ajross 1y agoYes, because if there's one thing computer vision solutions have historically had trouble with, it's being fooled by paint. The ludditism in this thread is shockingly strong.
- itishappy 1y agoCV systems absolutely do struggle with this... https://www.youtube.com/watch?v=U1MigIJXJx8 https://www.youtube.com/watch?v=U1MigIJXJx8
- ajross 1y agoYes, and that's considered a bug to fix, and can be. CV systems are widely applied to find camouflaged and obscured objects! Literally every automated wildlife camera is proof that this is a silly point.
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- echoangle 1y agoI guess you’re pointing out that there’s no identification. But it’s still locating stealth fighters.
- nradov 1y agoIt's really not. It's a toy demo of visually locating aircraft at relatively short range under ideal weather conditions. So what.
- sigmoid10 1y ago* as long as it's a bright sunny day Good look doing that at night or when it's cloudy.
- Sanzig 1y agoI'd also be curious about the detection range, even on a sunny day. Stealth doesn't mean the aircraft is invisible to radar, it just means it has a very low radar cross section, so you can't detect it from very far away. Fly close enough to an air defense radar, it will reflect enough energy to show up, it's not a black hole. The point of stealth is to make it impractical and uneconomical to build an air defense system with a high enough density of expensive high performance radars to reliably detect the aircraft.
- throwaway48476 1y agoMost stealth aircraft are only stealthy against the higher frequency radars.
- nradov 1y agoAnd only the higher frequency radars are really useful for interception or weapons targeting. The lower frequency radars are good at long-range detection but they're far less precise. Early stealth aircraft designs like the F-117 and B-2 were optimized for signature reduction in the frequency bands most typically used by air defense and fighter radar sets. Newer designs like the B-21 and F-47 supposedly have "broadband stealth" which reduces radar cross section across a broader range of radar bands but details are classified.
- smallmancontrov 1y agoThe "stealth aircraft hate this one weird trick" conversation also has to contend with jamming, because many of the techniques that work great at spotting stealth aircraft in peacetime are especially vulnerable to jamming. This makes them far less useful in an actual conflict.
- netsharc 1y ago> This technique can also be used to detect drones from many kilometers away Sudden spike of git pulls from Ukraine for the repo...
- ashoeafoot 1y agoAI + radar shadow aka passiv radar?
- cess11 1y agoThe ukrainians are very good at this already. Since drone swarms typically arrive at night they tend to prefer sound sensors.
- freefaler 1y agoAt night in Ukraine they use microphone arrays to track the drones: https://www.twz.com/land/thousands-of-networked-microphones-are-tracking-drones-in-ukraine https://www.twz.com/land/thousands-of-networked-microphones-...
- pj_mukh 1y agoSuper cool! Though cloud cover disabling your detection technique may make this infeasible for anything but low-altitude drones. One small nit: Calling Ray-tracing "Not AI" is like calling Matrix Math "Not AI". It's definitely a core component of a lot Machine Perception (i.e. AI) tasks. I'm guessing OP meant "Without using any costly CNN or Transformer inferencing", which is actually a clever achievement.
- eloisius 1y agoHe didn’t go into detail on how the cameras are calibrated by I wonder if he’s using stars to do that or what. Standard SfM would struggle with such featureless images and wide baseline.
- bagels 1y agoI thought: airplanes, the sun, the moon could all work
- eloisius 1y agoYou need a lot more than one reference though. At minimum I think you need 8 correspondences to solve for the camera’s pose. Things like airplanes could work if you had enough of them, but then the imagery in all your cameras would have to be shutter synced, which is impractical with a bunch of web cams
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- iamleppert 1y agoHe doesn't mention how he calibrates the camera extrinsics or intrinsics. This isn't new, it's basic structure from motion. He is going to be amazed when he "discovers" photogrammetry and bundle adjustment next. I checked out the code and there is no consideration for camera parameters it seems. It's a neat demo but impractical given the need for precise camera calibration over distance. Long baseline stereo has problems unless you can figure out how to keep the cameras aligned within fractions of a mm over great distances.
- robocat 1y agoAt 2:39 he talks about camera orientation and says that he has a solution. What he is doing isn't long-baseline stereo imagery? And clearly is not aligning the cameras: I'm guessing he is ensuring they don't wobble and he is solving the camera orientation outside of the code you can see (maybe using reference objects - sun or daytime moon?). I enjoyed his ponderings on bird-strike avoidance - maybe commercialisable. The asteroid detection seemed way more farfetched (light gathering is hard).
- eloisius 1y agoIn order to project the rays into the voxel grid and have them intersect when they are projecting the same object, the cameras do need to be calibrated. This is very much multi-view stereo CV. I’d guess that he’s taking nighttime photos and comparing with a ground-truth star map and choosing correspondences to compute a rotation/translation matrix for each camera.
- stefantalpalaru 1y ago[dead]
- mikewarot 1y agoIs anyone else here interested in actually trying this? I live near a fairly active small airport in Lansing, Illinois, and in the flight paths of everything going to/from Midway and Ohare, so combining this with ADSB might make for some interesting sources of calibration data, and a way to debug this algorithm. I think a neighborhood of Raspberry Pi based cameras networked together could prove quite effective. I wonder if all the installed Ring door cameras could do this in a national security emergency. I further wonder if it's being done to the US (with the current installed camera base) by China or others.