[HN Gopher] Spy camera detection using smartphone time-of-flight...
___________________________________________________________________
Spy camera detection using smartphone time-of-flight sensors
Author : Nirali_Feige
Score : 421 points
Date : 2021-11-18 16:21 UTC (6 hours ago)
(HTM) web link (dl.acm.org)
(TXT) w3m dump (dl.acm.org)
| ww520 wrote:
| Does the app take pictures to find the lens? Or videos?
| frizensami wrote:
| It's analyzing the camera feed in real time, so more like a
| video.
| ww520 wrote:
| Good to know. Yes, continuous video feed is easier to spot a
| light source. Can do differential analysis.
| qwertox wrote:
| Here's a demo video [0] of the app. It is embedded in the
| author's website [1]
|
| [0] https://www.youtube.com/watch?v=AFjGQNaqmXA
|
| [1] https://sriramsami.com/research/
| HackOfAllTrades wrote:
| A stand-alone Single-Point LIDAR might be used to remove the
| high-end phone requirement. Should interface to a phone USB port
| with a simple UART/I2C-USB adapter. Search Amazon.com for
| LIDAR finds 'Lidar Range Finder Sensor Module TF-Luna, Single-
| Point Micro Ranging Module 0.2 to 8m Compatible with Pixhawk,
| Arduino and Rasppbarry Pi with UART / I2C Communication
| Interface' $25. And 'MakerFocus TFmini-s Micro Lidar Module
| 0.1-12M Lidar Range Finder Sensor Obstacle Avoidance Sensor Tiny
| Module 1000Hz Single Point UART I2C IO Compatible with Pixhawk Ar
| duino and Raspberry Pi' $39. The 2nd one is waterproof.
| HackOfAllTrades wrote:
| Also on Amazon 'Worldoor CC308+ Multi-Detector Full-Range All-
| Round Detector For Hidden Camera / IP Lens/ GMS BUG / RF Signal
| Detector Finder , CC308 + detector hidden mini camera/IP
| camera/general manager/radio frequency signal detector
| instrument' <$20.
|
| And several similar hidden camera detectors. I have no idea how
| well/badly this sort of device works.
| anthomtb wrote:
| The acronym should be removed from the HN title. LAPD does
| nothing but sow confusion when used as the first word here.
| frizensami wrote:
| Author here, sorry, I didn't post this (but it is the paper's
| title). Hopefully it gets corrected.
| [deleted]
| errcorrectcode wrote:
| Molka is/was a problem in Korea. I wonder how it compares to
| SpyFinder Pro which seems like it's 95%+.
|
| https://www.kickstarter.com/projects/spyassociates/spyfinder...
| max47 wrote:
| that kickstarter campaign is borderline a scam. They have an
| msrp of 400$ for a Chinese gadget you can by for <10$ online.
| And no, their LEDs are not special and you can source better
| ones from digikey for less than 1$.
| djmips wrote:
| Borderline. You are being charitable.
| frizensami wrote:
| Good question. We evaluated the "K18" hidden camera detector,
| and not the SpyFinder, but they use an identical principle.
| schleck8 wrote:
| While it's especially bad of a situation in South Korea, it has
| become a serious issue globally.
|
| > The same poll found that one in 10 guests (11%) had found
| hidden cameras in an Airbnb rental.
|
| https://www.forbes.com/sites/suzannerowankelleher/2020/01/27...
| cf100clunk wrote:
| "Tiny hidden spy cameras concealed in sensitive locations
| including hotels and bathrooms are becoming a significant threat
| worldwide." I think motel room tenting and indoor foil-wearing
| might seem to be more justifiable, less paranoiac. Who knew?
| woeirua wrote:
| I wonder how hard it would be to engineer a material that you can
| put on top of the hidden camera lens that would greatly diffuse
| the specific frequency range of light that these ToF sensors use
| while permitting mostly visible light through? If so, it might be
| possible to defeat this approach relatively easily.
|
| Looking at what the DL filter is doing, I wonder how well this
| really generalizes. It seems that many of those examples are
| virtually indistinguishable to a human (hence the high false
| positive rate for the naked eye experiments).
| jcun4128 wrote:
| Bring a 360 degree projector, up the ante
| frizensami wrote:
| w.r.t the material, it seems to be possible, since ToF sensors
| operate in a narrow 850 nm band. However, I don't know if a
| coating can be made that also doesn't overlap with the visible
| light range since 850 nm is somewhat close to red light, or
| whether that would be cheap if so (given that the hidden
| cameras themselves are only $1 at the moment).
|
| I also have similar reservations about the DL approach in
| general. What makes me more confident is that we trained on a
| relatively small number of objects (~10) and tested on a
| totally different set of 30 objects. We're also using very
| small regions-of-interest as inputs (5x5), so there's little to
| no overfitting on the environment or objects themselves.
| hyperstar wrote:
| What are the best ways of doing this without a smartphone?
| frizensami wrote:
| The free option: use your smartphone's flashlight and try to
| spot unnaturally bright / colored reflection.
|
| If you want to spend some money and don't mind carrying an
| extra device: probably any of the "hidden camera detectors" on
| the market will be at least somewhat useful. K18, CC308+, etc.
|
| We're trying with our work to get better or at least equivalent
| results without having to use external devices.
| [deleted]
| benbojangles wrote:
| similar technology exists on ebay for under $5, you plug it into
| the phone's usb port and it emits ir led lighting and back into a
| lens
| chris_wot wrote:
| Can you supply a link to one of these devices?
| aaronax wrote:
| This reminds me in a way of the yacht with a system that detects
| cameras taking a picture of the yacht and sends a beam towards
| the camera to wash out the image.
|
| https://petapixel.com/2012/10/28/worlds-largest-private-yach...
| frizensami wrote:
| Pretty interesting idea. In fact, there are a number of
| military-related systems to spot sniper scopes (generally
| optics) with lasers, which I expect is similar to what they
| used here.
| iseanstevens wrote:
| Clever! Thanks :)
| victoraaa wrote:
| fdsd
| coretx wrote:
| Did the Rubidium price go up already ? ;-)
| jeffbee wrote:
| I'm having a hard time seeing how the obsolete and not exactly
| tiny OV2640 was crammed into that electrical plug. The integrated
| module is a 10mm cube with a 1/4" lens and to be useful it needs
| a power supply and either a storage controller or wireless
| network interface.
| frizensami wrote:
| We just used the OV2640 module itself
| (https://www.aliexpress.com/i/4000036275403.html) which is
| pretty small. While we didn't actually include a little battery
| and perhaps something like an ESP-32 to control it, I'm pretty
| sure those could fit inside the plug if hollowed out.
| SubiculumCode wrote:
| LAPD is not the Los Angeles Police Department, despite what we
| all were thinking.
| [deleted]
| micahcc wrote:
| Ok I'm not crazy
| abfan1127 wrote:
| what is it?
| throw_away wrote:
| > To answer this question, we propose LAPD (Laser- Assisted
| Photography Detection)
| simonebrunozzi wrote:
| I would be curious to know what would be the best method/tool to
| detect hidden cameras in places you visit (e.g. hotels, AirBnBs).
| I looked for devices on Amazon.com and found nothing that seems
| to be really good at detection.
| [deleted]
| elric wrote:
| So, could this be used to find better hiding spots for hidden
| cameras?
| [deleted]
| frizensami wrote:
| Yeah, that's fair. If someone really wanted to do this though,
| they could also just use existing products like this one:
| https://www.amazon.com/Worldoor-Multi-Detector-Full-Range-
| Al....
| DennisAleynikov wrote:
| absolutely, at least against this method of detection
| dclowd9901 wrote:
| Maybe, but realistically, since the sensor uses the properties
| of a camera lens to detect the camera itself, I would have to
| bet there is little that could actually be done to obscure the
| hidden camera and also still get a usable image from it. This
| is a pretty brilliant detection method.
| nybble41 wrote:
| It might be easier to design the room to create false
| positives and undermine trust in the detectors. Assuming you
| have that kind of influence, anyway. That's not an option if
| you're just trying to plant a camera in an existing room.
|
| I assume minimizing the aperture would be a fairly reliable
| way to avoid detection. A pinhole camera would be hard to
| find by any optical technique, though the video quality would
| suffer. Perhaps one could project through a pinhole onto a
| screen and record the projection, so the sensor is angled
| away from the room?
| frizensami wrote:
| That's an interesting idea: trying to create so many false
| positives that the user gives up. We're already removing
| around 100+ false positives per frame at the moment in
| difficult cases, so perhaps it's possible to overwhelm the
| filters with very maliciously designed environments.
|
| I think the easier way would be to hide the cameras in much
| harder-to-reach places so that it's inconvenient for the
| user to get their smartphone near. This might reduce the
| kind of videos that can be taken, but maybe an attacker
| will find that a reasonable tradeoff.
| djmips wrote:
| Probably the very smart spy camera can detect off axis
| TOF artificial light and close a shutter over the lens.
| Assuming your app integrates over the scanning motion,
| the camera won't be detected while it's shutter is
| closed. After the illumination is completed the spy
| camera can re-open it's shutter.
|
| The spy camera could also something like your system to
| detect the phone camera and take defensive measures.
| frizensami wrote:
| Yes, perhaps. At the very least, adding a variable
| shutter and extra logic will drive up the price of the
| camera, which will be some consolation.
| raldi wrote:
| "Specifically, the hidden camera [...] reflects the incoming
| laser pulses at a higher intensity than its surroundings due to
| an effect called lens-sensor retro-reflection. This occurs when
| almost all light energy impacting an object is reflected directly
| back to the source"
| polishdude20 wrote:
| Given this, can you just hold up a flashlight right next to
| your head and look around the room for bright spots?
| frizensami wrote:
| This is actually one of the recommended methods if you have
| no other options. It's not particularly good otherwise
| because of the limited visibility cone of the hidden camera
| reflections. From experience, the flashlight often tends to
| occlude the reflections you want to see, or the user isn't in
| the right place to see the reflections (near the flashlight).
| gpt5 wrote:
| That's exactly how detection tools work today.
|
| Here is a random one:
|
| https://www.lexuma.com/products/lexuma-xscan-portable-
| hidden...
| xipho wrote:
| Likely. Headlamps are well known tools for collecting spiders
| at night, when positioned just right they will reflect off
| the spider's eyes as you move your head around. It's an
| amazing thing to see spiders _everywhere_.
| brokenmachine wrote:
| Thanks for giving me nightmares.
| lapetitejort wrote:
| For peace of mind that sounds like the _worst_ tool to use.
| pasker wrote:
| I remember we were spotting alligators at the Amazon river
| with flashlight and their eyes reflections :-)
| gorgoiler wrote:
| It is _the_ standard way of detecting concealed lenses.
|
| Random google result:
|
| https://www.pimall.com/nais/startfinder.html
| rtkwe wrote:
| The light returns pretty directly to the source which is why
| most devices designed to use that detection method have the
| illuminators around an eyepiece so there's less distance
| between the illuminators and your eye.
| micahcc wrote:
| It took me a full minute to realize this wasn't the Los Angeles
| Police Department's R&D division
| [deleted]
| chris_wot wrote:
| What I would like to know is - how do you detect who is using an
| IR blaster?
| samstave wrote:
| If there was literally ANY metric I would want in a HUD; 'How
| many cameras are viewing me now, and where are they' has got to
| be the top of the list...
| jcun4128 wrote:
| > system that leverages the time-of-flight (ToF) sensor on
| commodity smartphones
|
| I think only the high end iPhones/iPad have these type of cameras
| right now right?
|
| I'd also be curious about the exact angle you have to hit to get
| a reflection
|
| Probably wouldn't work but bright flash in a room?
| frizensami wrote:
| Great question about the angle actually. There's previous work
| by an applied physics group [1] that shows the detectable
| field-of-view from the camera is about 20 degrees. Our
| experiments also confirm that.
|
| We also think using the smartphone flashlight (if that's what
| you mean) is the best way forward. That's already very helpful
| (and recommended) for humans to find hidden cameras, and it
| should be a useful extra modality for our work too.
|
| [1] https://ieeexplore.ieee.org/document/8790792
| jcun4128 wrote:
| You don't have to answer but, I'm assuming by the phone's API
| you can steer the beam/have an exact precision known of the
| minimum angle you can sample? That's pretty cool tech to work
| with.
| frizensami wrote:
| Unfortunately we can't steer the ToF beam, so the user has
| to move the phone around to multiple positions (a 2D grid
| of positions, basically). The app provides pretty clear
| guidance on where to move the phone to cover all possible
| spots, though.
| semi-extrinsic wrote:
| My Huawei P30 Pro from 2019 has a ToF sensor, so I don't think
| it's very uncommon?
| jcun4128 wrote:
| Yeah I guess my phone is not in that tier... it looks to be
| marked up 2x from GSMArena's prices... but $150 vs. $350
| pricing. Also the Moto G Stylus (my phone) is from 2020
| frizensami wrote:
| Yep, there are a pretty decent number of smartphones with it,
| and I think the trend is moving in the right direction
| (iPhone 12 Pro had it and Apple included it in the iPhone 13
| Pro too).
| z3t4 wrote:
| If the spy camera has infrared leds then you can detect those by
| removing the infrared filter from a camera, can be done on some
| smartphone cameras programmatically I think.
| Scoundreller wrote:
| In a dark room, you can point an old-style remote control at an
| iPhone camera and see button presses light up the IR
| transmitter.
|
| I do this to test their batteries :)
|
| But older Cell-phones (flip phones) with CMOS sensors used to
| be really good at this as they wouldn't filter much IR in order
| to work better in low-light conditions.
| SubiculumCode wrote:
| I was really hoping that they had an app I could install, as they
| implemented LAPD on Android.
| frizensami wrote:
| Hey! Author of the work here. We just finished presenting this
| at a conference yesterday, so we're working on open-sourcing
| the code now with some feedback from the community. It's got
| some warts because of API limitations (no way to automatically
| align color and ToF cameras, so we're manually doing that).
| SubiculumCode wrote:
| Cool work. It would be great for scanning hotel rooms.
| frizensami wrote:
| Thank you!
| rbanffy wrote:
| You'll still need the laser emitter. Here I would hope the
| emitter can be operated in a high-power small-target mode to
| also obliterate the detected cameras. Extra points if it can do
| so autonomously - I leave it over the bed, go out for dinner,
| and come back to a room without any cameras.
| [deleted]
| jaywalk wrote:
| You have to go to the second page of the full PDF to even see
| what LAPD stands for, which is Laser-Assisted Photography
| Detection. They need to be more mindful of this, especially when
| they made up the acronym themselves.
| intrasight wrote:
| Cool tech. Too bad about the paper title. One should never use
| a novel acronym in an academic title IMHO.
| w0mbat wrote:
| LAPD is worse than novel, it is already used in another
| context where it is very well known.
|
| Most people will already know this, but LAPD = Los Angeles
| Police Department, often featured in TV shows, films and the
| news.
| ska wrote:
| > Most people will already know this, but LAPD
|
| s/most people/most americans/
|
| plus some non americans of course, but it's not a global
| association by any means.
| elzbardico wrote:
| The authors are from Singapore. The association is not that
| direct for non-americans. Actually, I only noticed it after
| several people mentioned it here.
| PeterHolzwarth wrote:
| 95.75 percent of the planet is not American, if you are
| partially referring to the acronym of the police department.
| haswell wrote:
| Regardless of this, it's generally good form to define an
| acronym the first time it's used, even if there was no
| duplication/overlap.
|
| With that said, while you're correct:
|
| - A significant portion of tech advancement is US-centric, so
| I understand the instinct to ask for clarification
|
| - I'd argue that the LAPD is relatively well-known world-
| wide, much like the RCMP, or RAF, or other very famous
| organizations
| Jolter wrote:
| Well, you just got me to Google "rcmp". That's just one
| data point of course, and I was indeed aware of their
| informal name from popular culture.
| [deleted]
| [deleted]
| fortran77 wrote:
| I was working on a project like this and we relied on the fact
| that the IR filter on most cameras was a retro reflector. Remove
| the IR filter and the camera will be harder to find. I think the
| technique here also depends on the IR filter's characteristics.
| frizensami wrote:
| That's a good point. I'm not sure how the removal of the IR
| filter will affect this work. I mentioned some prior work from
| the physics side [1] in another comment that explores the
| reflection characteristics in more detail. I don't think they
| explored the IR filter contribution as well, so this could be
| an interesting direction.
|
| [1] https://ieeexplore.ieee.org/document/8790792
| sturgl wrote:
| IR cut filters used in smartphone-style cameras are typically
| reflective.
|
| Installing an absorptive IR cut filter on top of the lens
| would decrease the amount of reflected light, and might
| hinder your approach. Those are pretty cheap to buy, so you
| could try it out pretty easily.
| injidup wrote:
| I know a woman who discovered a hidden camera in the female
| toilet at work disguised as some kind of utility hook on the
| door. Cheap to buy on amazon!! The SD card inside had pictures of
| the company owner's desk but not an actual picture of him. The
| police declined to prosecute because of lack of evidence.
| xanaxagoras wrote:
| Gross.
| stronglikedan wrote:
| > The police declined to prosecute because of lack of evidence.
|
| Thank goodness! Imagine being convicted of a crime because some
| perv took some pictures of your personal stuff in an attempt to
| frame you.
| spoonjim wrote:
| Prosecute and convict are different. You should at least pull
| his credit card transactions and see if he recently bought
| it.
| jjcon wrote:
| That would still be circumstantial wouldn't it?
| mywittyname wrote:
| Lots of evidence is circumstantial.
|
| Contrary to popular believe, circumstantial evidence is
| not bad evidence. In isolation, it might not be enough to
| convict, but when used in conjunction with other
| evidence, it can create a damning case.
|
| 1. The camera contained pictures of owners desk.
|
| 2. That model camera was purchased on amazon by the
| owner.
|
| 3. The serial number of the camera indicates that it was
| sold on amazon and produced around the time of purchase
| by the owner.
|
| 4. The camera was found in a place the person had
| reasonable, unrestricted access to.
|
| 5. owner was found in possession of pictures that look to
| have been taken by the device, in the position where the
| device was originally discovered.
|
| * I'm not asserting these facts are true, just stating
| them for the sake of example.
|
| In isolation, each of these pieces of evidence don't
| prove much, but in totality, it is highly unlikely that
| all of those things would happen to an innocent person.
| Jury's don't need to be 100% certain to convict, they
| need a preponderance of evidence.
|
| I can see why a prosecutor wouldn't pursue this case
| against a rich person though. The police are unlikely to
| do a good job at collecting evidence, a good lawyer will
| get enough of it thrown out, victims probably won't want
| to testify anyway, and being a business owner, this
| person might have clout with local politicians who will
| make trouble.
| GekkePrutser wrote:
| Sounds like that scene from Austin powers :) where he
| keeps saying the pump isn't his.
|
| But you're right that's pretty damning.
| HWR_14 wrote:
| I mean, if you showed him buying the same model from
| Amazon and it had pictures from him testing it in his
| office, that's probably enough to convict.
| rtkwe wrote:
| Individual pieces of evidence are often circumstantial,
| taken together they're enough to prove something.
| moron4hire wrote:
| Most evidence is. "Circumstantial" doesn't automatically
| make the evidence useless.
| IIAOPSW wrote:
| Yes, which is insufficient for a conviction but
| reasonable suspicion to get a warrant.
| dzhiurgis wrote:
| Add fingerprints and DNA from SD card, logs on PC...
| [deleted]
| mike-cardwell wrote:
| To be fair to the owner, that would be a good way of setting up
| somebody else to take the fall if the camera was discovered.
| frizensami wrote:
| Hey! Sriram here, author of this work. I'd be glad to answer any
| questions. There's also a short talk I gave about this here
| (https://www.youtube.com/watch?v=t4Txdhlji4k) if that's helpful!
| djmips wrote:
| Would your system work against flat cams?
| https://youtu.be/BdgwO_i5p54
| megablast wrote:
| Does it work against something that doesn't exist yet??
| frizensami wrote:
| Thats very interesting, first time hearing of it. Not sure,
| really depends on what kind of reflection it generates when
| light hits it, and because of the unique design I'm not sure
| what that will be.
| deegles wrote:
| What are the properties of the cameras that don't get detected?
| Wouldn't bad actors just use the same app to check if their
| cameras are detectable at installation time?
| frizensami wrote:
| So far the biggest issue is if the camera is angled oddly
| away from the user (basically, outside the 20 degree
| observable FoV). Another issue would be if they manage to
| install a larger camera that returns larger reflections
| (which we filter out).
|
| Regarding using the app to check, I guess that applies for
| the existing handheld detectors as well. It's definitely
| something that intelligent attackers can try to plan for, but
| we havent tested the adversarial robustness of the system
| right now. That would be a very interesting direction for us
| as well.
| frizensami wrote:
| But at least for the larger camera case, we can just
| increase one of the filtering thresholds for reflection
| size, which is already doable on the UI
| starwind wrote:
| Do you have any plans release this as an app I could install on
| my phone?
| frizensami wrote:
| Yes, we do! There are a couple of user-facing annoyances at
| the moment, one of which I mentioned in another comment
| (hacks to align the color and ToF images). Hopefully these
| API limitations are removed soon, or we find better
| workarounds.
| david_allison wrote:
| Would you consider open sourcing the app as-is?
|
| You've got a community of people who're willing to spend
| time polishing.
| frizensami wrote:
| It's definitely something I'm considering. The only hard
| blocker now is a hashmap that checks for our test phones'
| unique ID and applies a fixed transform to align both
| cameras. Right now, any other phones will cause an
| immediate crash. Minimally I think we need to disable
| this and maybe include a small UI to let users put in the
| alignment parameters (just a scale + offset).
| frizensami wrote:
| Also I appreciate the interest, thank you. I'm heading
| back from the conference over the next few days, so I
| should be more free to take a look at it soon.
| david_allison wrote:
| Feel free to shoot me an email (in profile) if you'd like
| this UI done. No need for anything else other than the
| source code.
|
| It'd be a massive benefit to society to make this widely
| available.
| jmnicolas wrote:
| If you do release it, is it possible to not depend on
| Google services please? I am almost a year in my degoogled
| life!
| frizensami wrote:
| I would love to, but I'm not sure how yet without a major
| re-write. The augmented reality code we completely rely
| on is part of Google Play Services for AR. I definitely
| do understand the benefit of degoogling, so maybe it can
| be a community effort once I opensource it.
| seaman1921 wrote:
| Please don't make the functionality worse just to please
| the de-googled hacker=news crowd.
| Iolaum wrote:
| Awesome, if there's a waiting list or a website that we can
| join or follow to be notified of a release please share.
| frizensami wrote:
| Sadly no project-specific page yet, but I'll definitely
| update on my page at https://sriramsami.com/research/ (I
| think there's an RSS feed?) when it's active.
| specto wrote:
| https://sriramsami.com/feed.xml
| iamwil wrote:
| Where do we sign up to be notified when this is released?
| Mikejames wrote:
| +1
| datameta wrote:
| same here
| 123pie123 wrote:
| I do like this
|
| what technology advancement would be needed to increase the
| detection rate and reduce the false positives?
| frizensami wrote:
| Right, a few things would be very useful:
|
| - Increasing the resolution of ToF cameras (right now images
| are around 320 x 240) --> reflections from hidden cameras can
| then be more detailed, whereas now it's only 1 or 2 pixels
| each.
|
| - Increasing the bit-depth of ToF images - right now every
| pixel is only 3 bits (8 colors). It's very hard to
| differentiate bright hidden camera reflections from
| everything else, so we had to do a lot of work for that.
|
| - API improvements in conjunction with augmented reality
| libraries, e.g., a) allowing Android devs to enable the
| flashlight when AR apps are running b) more raw access to the
| ToF sensor if possible
| debt wrote:
| 320 x 240, is this the resolution of the depth data
| provided by the LiDAR sensor?
| frizensami wrote:
| Yep, exactly.
| pnw wrote:
| Samsung started marketing their ISOCELL Vizion 33D camera
| in 2020 with 640 x 480 resolution. So it's likely we'll
| see better ToF resolution announced in some phones in the
| next year or two.
|
| Great project btw!
| frizensami wrote:
| Thank you! Actually, my understanding when I started this
| project was that I would get a 640 x 480 image (IMX516
| sensor). However, I could only get a 320 x 240 image from
| the sensor through the Android API, so that was a bit of
| an oddity.
| datameta wrote:
| The results are even more impressive with that
| considered!
| frizensami wrote:
| Thank you! Hoping for higher resolutions soon.
| 5faulker wrote:
| The next project would be creating another device to detect
| these spy camera detectors
| stinos wrote:
| A hidden camera which detects ToF sensors
| 14 wrote:
| I was wondering if cameras started using anti-reflective glass
| would this prevent detection? Some of the glass I've looked up
| say they reflect less than 1% of light. How sensitive is your
| app could it detect 1% reflections? Thanks
| nomel wrote:
| It's lens + sensor stackup reflection. Camera sensors are
| much more reflective than a lens.
| 14 wrote:
| So would something like anti reflective glass for light
| coming into the camera then another layer of like tint that
| will stop light from reflecting back out if the camera? Ya
| I know that doesn't exist but That is because they were not
| trying to do undetected as hard before. Just thinking of
| counter surveillance techniques.
| PaulDavisThe1st wrote:
| > Just thinking of counter surveillance techniques.
|
| Counter-counter surveillance techniques, IIUC.
| frizensami wrote:
| Yep, the combination is highly reflective. I cited another
| work (by a physics research group) in a comment that
| modelled and tested this effect comprehensively.
| 14 wrote:
| Would you speculate if anti reflective glass on the
| outside of the camera and a layer of one way tint on the
| inside that would allow light through but prevent it from
| reflective back out? I'm just thinking what we will
| expect in the future to sell the "undetectable spy
| camera".
| frizensami wrote:
| That's a great question. I'm not totally sure if this is
| possible. If it was, I think one-way mirrors would use
| this technology. For now, it seems like they only work
| because they only let 50% of the light through + there's
| a brightness differential between both sides. Perhaps
| someone more informed about this could chime in.
| ticklemyelmo wrote:
| Could this be applied to longer-range applications? Concert /
| theater cameras, camera / binocular observers, counter-sniper
| detection?
| frizensami wrote:
| While the broader technique should work for those
| applications, the platform (smartphone ToF sensors) probably
| won't. Smartphone ToF sensors have a pretty limited range. We
| were only able to detect cameras within 1 metre of the
| smartphone because we're really using the hardware for
| something it's not intended for.
|
| For the applications you suggest, there are some existing
| military-looking devices out there that use multiple lasers
| to find sniper scopes, for example. My basic searching shows
| at least https://www.ldsystems.us/product/sniper-optics-
| detector/#, though I'm sure there's more.
| mensetmanusman wrote:
| Great work!
|
| Do you have a link to where you can buy these types of time of
| flight lasers/sensors? Curious about the additional hardware
| cost versus sensitivity.
| frizensami wrote:
| Thank you!
|
| While this work operates on ToF sensors that are already
| present in smartphones (e.g., Samsung S20+/Ultra), a
| Microsoft/Azure Kinect should also be a valid option because
| it has a depth camera as well. It has a higher resolution and
| bit-depth as well.
|
| We initially intended to compare against the Kinect, but it
| doesn't fit the use case (something that you can have on you
| at all times). However, it could be a cheap choice for a
| different kind of deployment (automated hidden camera
| detection with robots, perhaps?)
| tootie wrote:
| So I had no idea phones have ToF sensors these days. Do
| most phones have them or only the high-priced flagships?
| What are the actual intended uses for them?
| frizensami wrote:
| High priced flagships have them but there are also a few
| midrange phones like the Huawei P30 Pro that have them
| too. The trend seems pretty positive towards more ToF
| sensors in phones, especially because Apple has had them
| for two iPhone Pros in a row now.
|
| They're basically for augmented reality applications
| because they sense depth. Placing objects at the right
| size and scale in the augmented view is much easier and
| more accurate with the ToF sensors, for instance.
___________________________________________________________________
(page generated 2021-11-18 23:00 UTC)