7 ms·

How taking pictures through windows can inadvertently reveal your location

161 points by sebkomianos 12y ago

SomeoneWeird 12y ago
This is pretty neat, I wonder how hard it would be to automate using gmaps for an approx location.
chatman 12y ago
If it comes to stalking someone, why just a hotel picture? Any picture, and previous context (e.g., "Miami, I am here"), can be tracked down to the exact location.
- nardi 12y ago
  I was going to say the same thing. This has little to do with hotels or reflections. Any picture at all with a skyline in it, given a good enough 3D map and some software (maybe the NSA has some already?), should be enough to pinpoint you pretty closely, depending on the nearness of the skyline and the quality of the picture.
awjr 12y ago
I'll be taking this material and creating a tutorial "101: How to stalk a celebrity and make them feel slightly uncomfortable" However, in all seriousness, nice levels of deduction going on here and only slightly creepy tweets :)
pearjuice 12y ago
Reminds me of the ridiculous enhancement processes in Hollywood. Except this time... it's real. https://www.youtube.com/watch?v=LhF_56SxrGk https://www.youtube.com/watch?v=LhF_56SxrGk
- JetSpiegel 12y ago
  What do you mean, Hollywood? Red Dwarf was made in the UK. https://www.youtube.com/watch?v=6i3NWKbBaaU https://www.youtube.com/watch?v=6i3NWKbBaaU
_mulder_ 12y ago
Isn't revealing your location the whole point of taking a picture from your hotel window and sharing it with the world on Twitter? I wouldn't be too surprised if I posted "I'm in Miami, and here's a view from my Hotel window" and someone was able to tell me the Hotel name and which side I was staying on. Infact, I'd be more surprised if someone couldn't! The techniques used are not particularly ingenious here, especially as most of the photo's seem to depict some obvious landmarks to provide an easy point of reference, especially when given the extra information to focus on a specific location.
- enscr 12y ago
  Granted that posting a pic from your hotel room, with emphasis on outside view doesn't leave a lot to be guessed but the author has done some reasonable sleuthing to be accurate, let's give him credit for that.
- hoggle 12y ago
  TL;DR Be mindful of reflections when taking a picture. "Conclusion Clear and simple: the reflected images in pictures might disclose information that you wouldn’t be willing to share, such as your location or other personal details."
  - _mulder_ 12y ago
    Whilst this could be the case in some photographs, like reading reflected documents or personal information, the ability to see a reflected light and a photo frame which therefore narrows your location down to one of 30-40 identical hotel rooms doesn't seem like personal information to be wary off. You're far more likely to inadvertently reveal personal information in the background of a photo of your actual hotel room that you are from looking out the window.
  - lamontcg 12y ago
    reflected images in pictures might also disclose that you just got out of the shower and didn't bother to put on any clothes yet....
- 12y ago
hoggle 12y ago
"Finally, do not forget that a reflection could be your enemy." On a tangent - I didn't realize that the google maps 3D rendering has gotten so good over the last couple of years. I wonder how hard it would be to scrape the point data and satellite textures to source a GTA map, I'd love to cruise through actual Vice City with the GTA V engine. If you haven't checked it out yourselves - breath-taking WebGL view of Miami (Chrome, OSX): https://www.google.com/maps/place/Miami,+FL/@25.7747883,-80.1751686,528a,35y,261.17h,71.49t/data=!3m1!1e3!4m2!3m1!1s0x88d9b0a20ec8c111:0xff96f271ddad4f65 https://www.google.com/maps/place/Miami,+FL/@25.7747883,-80....
- lookingsideways 12y ago
  If you're on OSX, try it out in Apple Maps, I find their 3D views superior to Google's and it's been available in more locations that I've looked at. On the iPad you also get more control over viewing angles, I was surprised that you lose that on the desktop.
  - lelandbatey 12y ago
    Hold the 'Ctrl' key and you can use the mouse to rotate to any angle you like.
- josephcooney 12y ago
  Not the first time this has caught people out. (slightly NSFW) http://www.messandnoise.com/discussions/4112452 http://www.messandnoise.com/discussions/4112452 I refuse to believe some of these are "accidental".
pjc50 12y ago
This reminds me, can't find it right now, but there is a picture circulating on Twitter of a safari park warning sign: "Please make sure you turn off location and be careful about sharing photos of our rhino on social media, you may give away its location to poachers"
- user24 12y ago
  https://twitter.com/robinsloan/status/463343201865048064 https://twitter.com/robinsloan/status/463343201865048064
  - nnq 12y ago
    Thanks dude. That bush to the right is a rare plant that only grows in a 600 sq miles radius in a known part of Africa. The recon guys are already there and they said they've found the only manufacturer of plastic signs around that area that uses that font as the default one. Now they are "talking" to him about his customers. Once we have certain coordinates, we'll send them to our team of guys with guns on the ground and to the extraction and cargo transport teams. I can already feel the sweet smell of freshly powdered rhino horn :) In the olden days we would have had to track the guy who took the picture and have a lengthy private talk with him, risking to expose ourselves in a "lawful" country, but this makes it so much easier...
  - pbhjpbhj 12y ago
    Trying to find the source of that image - Google lists it on a few tumblrs going back to 2010 (tumblr apparently started in 2007, who knew) - except when you go to the oldest of them it's only just been posted, today, not 2010. Google never seem to have been able to do dates reliably.
enscr 12y ago
Wait till the author can tell what you ate based on spectroscopic analysis of the reflection from the building across the shore. A la CSI syle.
- laumars 12y ago
  "Zoom in and enhance"
  - grkvlt 12y ago
    Techniques like superresolution make this quite possible from a grainy video image: en.wikipedia.org/wiki/Superresolution
quasque 12y ago
This reminds me of the child pornography case a few years back, where detectives were able to identify the hotels where the abuse took place via imagery of the rooms. Interestingly, rather than figuring it out themselves (as the search space was too huge), they crowdsourced it by releasing images with the child photoshopped out.
bitL 12y ago
A case for always using polarizing filter ;-)
berrypicker 12y ago
This is hardly "inadvertently" revealing your location: (1) they've told you where they are (extra from the actual Tweets, not the photos) and (2) these places are all near well-known landscapes. I mean good job on taking the time to actually do it but I doubt this could be done for the vast majority of photos like this.
beejiu 12y ago
Well, unless I know there is somebody out to kill me, why would I care about giving away my location?
- user24 12y ago
  e.g. "Finally safe from abusive ex, locked my door, staring out the hotel room window [pic]", or myriad other imaginable scenarios.
  - laumars 12y ago
    When you're put into protection (including from abusive spouses), the first thing the agencies involved do is tell you not to contact friends nor relatives. Posting a picture of their accommodation on social media would be the stupidest thing they could do - reflection or not. So if they proceed to do this even after being advised not to; then I have to question if subconsciously they really do want to be caught (it's saddening just how emotionally dependant victims of abuse are on their abusers). But this is now taking a tangent onto a whole other topic.
    - user24 12y ago
      What if they just ran away on their own? Anyway the point is there are plenty of situations where you'd want to hide your location but might erroneously think a photo from your window doesn't reveal too much info.
      - laumars 12y ago
        "> What if they just ran away on their own?" Happens less often than you'd hope. Usually such victims require support from others. "> Anyway the point is there are plenty of situations where you'd want to hide your location but might erroneously think a photo from your window doesn't reveal too much info." I'm sure there might be some fringe examples, but "plenty"? Nobody has yet suggested even one plausible example so far. And even the examples in the article were from people who didn't care about revealing their location to begin with (eg in the first example, the subject announced he was in Miami as well as taking that picture). But I'm sure there are some examples of people stupid enough to share a picture of their location and not realise it might reveal their location to other people; I'm rarely surprised by the stupidity of the worst case scenarios. But I also doubt those sorts of people who lack even that level intelligence would be the kind to people who read articles like these. So whichever way I look at it, I can't see anyone's life saved (metaphorically nor literally) by the research conducted by this author (as interesting as it might be to many of us).
Yardlink 12y ago
I was halfway through the article before I realized it wasn't going to be about a security vulnerability in MS Windows!
alkonaut 12y ago
Point is: when you post a view or a location name that's when you want to tell the world where you are. I'm not inadvertently revealing my location I'm very much advertently revealing it. I assume there are much more creepy techniques to tell where I am when I don't explicitly reveal it.
arrrg 12y ago
Using the reflections as additional information is very interesting. However, I’m not that surprised that views from windows can be relatively easily located. Andrew Sullivan has been running his View From Your Window contest for four years now and people have been guessing the locations of the photos with scary accuracy (as good as in the linked post). Here is the archive: http://dish.andrewsullivan.com/vfyw-contest/ http://dish.andrewsullivan.com/vfyw-contest/ Still, it’s probably more than 15 minutes work even in the best case scenario (and much, much longer in the worst case), can probably not be automated in any meaningful way (but that would be an interesting project, huh!) and is consequently only of interest to dedicated attackers, not general surveillance.
- abruzzi 12y ago
  And he doesn't even give a starting city or country. His readers have to narrow down the location using street signs, building types, car types, and other subtle hints. So if you don't want people to find you don't post pictures of where you are.
  - saraid216 12y ago
    > So if you don't want people to find you don't post pictures of where you are. This cannot be said enough. It's definitely worth educating people to the kinds of things they're exposing when publishing things like vacation photos, but most people shouldn't have a need for that level of information security.
hellbreakslose 12y ago
If you have to hide don't take a picture of where you are at. Also don't check in on fb from that place ;)
return0 12y ago
There is nothing inadvertent here.
mhb 12y ago
Possibly more interesting: Research shows eye-reflections in photos could be used to identify criminals: http://www.engadget.com/2013/12/29/eye-reflections-catch-criminals/ http://www.engadget.com/2013/12/29/eye-reflections-catch-cri...
- uptown 12y ago
  Dual Photography has always been the optical "trick" that's blown me away. Here's the demo video from Siggraph in 2005: http://www.youtube.com/watch?v=p5_tpq5ejFQ http://www.youtube.com/watch?v=p5_tpq5ejFQ Skip ahead to 4:19 for a succinct demo.
richbradshaw 12y ago
Also, taking photos of meals you are eating can inadvertently reveal your dietary choices. Look at that burger - you can see from the menu that this is a vegetarian restaurant - that means that the 'meat' isn't really meat at all but a bean and nut mixture.
jeroen 12y ago
Views out the window are also very useful for finding the exact location of real estate for sale or rent, when the ad only shows an approximate location.
joewee 12y ago
This only seems useful if it is automated and extremely fast. If you are law enforcement there are faster ways to do this. Like just calling in the city the "bad" guy last checked in at. And if you aren't, there are much easier ways to get info on the room someone is using, like social engineering. Which I'd actually one if the examples the author gave when he simply asked the victim in twitter what floor he/she was on. I haven't seen criminal scenarios where the bad guy takes a photo if his view or checks in on four square, that doesn't get rounded up fairly quickly.
frogpelt 12y ago
My takeaway: if you want to throw creepers like this guy off your trail, harvest a hotel picture from the internet and post it to your Twitter account.
ewindisch 12y ago
As a countermeasure, the article notes turning off lights and so forth. Seems the author hasn't heard of polarized lenses. Others note that it's not a real security concern, no, but using a FLD lens will result in better photos when shooting through glass! Use it!
deleted 12y ago
[deleted]
clarky07 12y ago
So, 99.9% of the information was gathered based on the actual photo, and .1% of it confirmed with reflections. Impressive. Hmm, this picture of a landmark came from the building near the landmark. How did you get that with just reflections?!?
jack-r-abbit 12y ago
I would think a person would be more concerned about other things (not location) being relieved in the reflection. Like the strippers you have in the room. Or the drugs.
jclarkcom 12y ago
From the title of the article I expected this to discuss a computer vision related technique for enhancing the camera location using reflections. Using techniques similar to those in photosythn, you can already determine camera location fairly accurately and easier than the manual work done by the article's author.
malandrew 12y ago
There may come a time when indoor pictures could reveal your location as well. If you were to create a database of lots and lots of architectural plans, you could conceivably use computer vision algorithms for determining dimensions of a room as a few more known bits of entropy for identifying an indoor location.
instaheat 12y ago
Who cares?
JTxt 12y ago
With a set of photos of the same static scene, it's possible to figure out the camera position, angle, and focal length of every camera, sometimes to millimeter accuracy. You just have to correlate the same features in each frame, then solve it. 3d motion trackers do this. (Blender.org has one. You can solve this same problem using it. Bring in public and street view photos of the area. It's a bit of manual work to put all the images in a movie then go frame by frame and tag features... But you could get much more accurate than the article.) The power is in having access to large databases of photos of everywhere, and even better if all the photos were taken the same way, like google's street view... and large amounts of computing resources to index and correlate all of the features from all of the images automatically. I would be surprised if there is not a project in some huge company or lab that can identify features in nearly any public outdoor shot and determine exactly where it was taken. (perhaps for intelligence or forensics) I believe this paper introduced me to the idea in 2006: http://research.microsoft.com/en-us/um/redmond/groups/ivm/phototours/PhotoTourism.pdf http://research.microsoft.com/en-us/um/redmond/groups/ivm/ph...
ilovecookies 12y ago
You might reveal your location but the person spying on you would have to be a stalker and a total creep, who basically have no life and nothing interesting to do. That's more scary than taking pictures with reflections IMO

161 points by sebkomianos 12y ago

This is pretty neat, I wonder how hard it would be to automate using gmaps for an approx location.

If it comes to stalking someone, why just a hotel picture? Any picture, and previous context (e.g., "Miami, I am here"), can be tracked down to the exact location.

nardi 12y ago
I was going to say the same thing. This has little to do with hotels or reflections. Any picture at all with a skyline in it, given a good enough 3D map and some software (maybe the NSA has some already?), should be enough to pinpoint you pretty closely, depending on the nearness of the skyline and the quality of the picture.

awjr 12y ago

I'll be taking this material and creating a tutorial "101: How to stalk a celebrity and make them feel slightly uncomfortable" However, in all seriousness, nice levels of deduction going on here and only slightly creepy tweets :)

pearjuice 12y ago

Reminds me of the ridiculous enhancement processes in Hollywood. Except this time... it's real. https://www.youtube.com/watch?v=LhF_56SxrGk https://www.youtube.com/watch?v=LhF_56SxrGk

JetSpiegel 12y ago
What do you mean, Hollywood? Red Dwarf was made in the UK. https://www.youtube.com/watch?v=6i3NWKbBaaU https://www.youtube.com/watch?v=6i3NWKbBaaU

_mulder_ 12y ago

Isn't revealing your location the whole point of taking a picture from your hotel window and sharing it with the world on Twitter? I wouldn't be too surprised if I posted "I'm in Miami, and here's a view from my Hotel window" and someone was able to tell me the Hotel name and which side I was staying on. Infact, I'd be more surprised if someone couldn't! The techniques used are not particularly ingenious here, especially as most of the photo's seem to depict some obvious landmarks to provide an easy point of reference, especially when given the extra information to focus on a specific location.

enscr 12y ago
Granted that posting a pic from your hotel room, with emphasis on outside view doesn't leave a lot to be guessed but the author has done some reasonable sleuthing to be accurate, let's give him credit for that.
hoggle 12y ago
TL;DR Be mindful of reflections when taking a picture. "Conclusion Clear and simple: the reflected images in pictures might disclose information that you wouldn’t be willing to share, such as your location or other personal details."
- _mulder_ 12y ago
  Whilst this could be the case in some photographs, like reading reflected documents or personal information, the ability to see a reflected light and a photo frame which therefore narrows your location down to one of 30-40 identical hotel rooms doesn't seem like personal information to be wary off. You're far more likely to inadvertently reveal personal information in the background of a photo of your actual hotel room that you are from looking out the window.
- lamontcg 12y ago
  reflected images in pictures might also disclose that you just got out of the shower and didn't bother to put on any clothes yet....
12y ago

hoggle 12y ago

"Finally, do not forget that a reflection could be your enemy." On a tangent - I didn't realize that the google maps 3D rendering has gotten so good over the last couple of years. I wonder how hard it would be to scrape the point data and satellite textures to source a GTA map, I'd love to cruise through actual Vice City with the GTA V engine. If you haven't checked it out yourselves - breath-taking WebGL view of Miami (Chrome, OSX): https://www.google.com/maps/place/Miami,+FL/@25.7747883,-80.1751686,528a,35y,261.17h,71.49t/data=!3m1!1e3!4m2!3m1!1s0x88d9b0a20ec8c111:0xff96f271ddad4f65 https://www.google.com/maps/place/Miami,+FL/@25.7747883,-80....

lookingsideways 12y ago
If you're on OSX, try it out in Apple Maps, I find their 3D views superior to Google's and it's been available in more locations that I've looked at. On the iPad you also get more control over viewing angles, I was surprised that you lose that on the desktop.
- lelandbatey 12y ago
  Hold the 'Ctrl' key and you can use the mouse to rotate to any angle you like.
josephcooney 12y ago
Not the first time this has caught people out. (slightly NSFW) http://www.messandnoise.com/discussions/4112452 http://www.messandnoise.com/discussions/4112452 I refuse to believe some of these are "accidental".

pjc50 12y ago

This reminds me, can't find it right now, but there is a picture circulating on Twitter of a safari park warning sign: "Please make sure you turn off location and be careful about sharing photos of our rhino on social media, you may give away its location to poachers"

user24 12y ago
https://twitter.com/robinsloan/status/463343201865048064 https://twitter.com/robinsloan/status/463343201865048064
- nnq 12y ago
  Thanks dude. That bush to the right is a rare plant that only grows in a 600 sq miles radius in a known part of Africa. The recon guys are already there and they said they've found the only manufacturer of plastic signs around that area that uses that font as the default one. Now they are "talking" to him about his customers. Once we have certain coordinates, we'll send them to our team of guys with guns on the ground and to the extraction and cargo transport teams. I can already feel the sweet smell of freshly powdered rhino horn :) In the olden days we would have had to track the guy who took the picture and have a lengthy private talk with him, risking to expose ourselves in a "lawful" country, but this makes it so much easier...
- pbhjpbhj 12y ago
  Trying to find the source of that image - Google lists it on a few tumblrs going back to 2010 (tumblr apparently started in 2007, who knew) - except when you go to the oldest of them it's only just been posted, today, not 2010. Google never seem to have been able to do dates reliably.

enscr 12y ago

Wait till the author can tell what you ate based on spectroscopic analysis of the reflection from the building across the shore. A la CSI syle.

laumars 12y ago
"Zoom in and enhance"
- grkvlt 12y ago
  Techniques like superresolution make this quite possible from a grainy video image: en.wikipedia.org/wiki/Superresolution

quasque 12y ago

This reminds me of the child pornography case a few years back, where detectives were able to identify the hotels where the abuse took place via imagery of the rooms. Interestingly, rather than figuring it out themselves (as the search space was too huge), they crowdsourced it by releasing images with the child photoshopped out.

bitL 12y ago

A case for always using polarizing filter ;-)

berrypicker 12y ago

This is hardly "inadvertently" revealing your location: (1) they've told you where they are (extra from the actual Tweets, not the photos) and (2) these places are all near well-known landscapes. I mean good job on taking the time to actually do it but I doubt this could be done for the vast majority of photos like this.

beejiu 12y ago

Well, unless I know there is somebody out to kill me, why would I care about giving away my location?

user24 12y ago
e.g. "Finally safe from abusive ex, locked my door, staring out the hotel room window [pic]", or myriad other imaginable scenarios.
- laumars 12y ago
  When you're put into protection (including from abusive spouses), the first thing the agencies involved do is tell you not to contact friends nor relatives. Posting a picture of their accommodation on social media would be the stupidest thing they could do - reflection or not. So if they proceed to do this even after being advised not to; then I have to question if subconsciously they really do want to be caught (it's saddening just how emotionally dependant victims of abuse are on their abusers). But this is now taking a tangent onto a whole other topic.
  - user24 12y ago
    What if they just ran away on their own? Anyway the point is there are plenty of situations where you'd want to hide your location but might erroneously think a photo from your window doesn't reveal too much info.
    - laumars 12y ago
      "> What if they just ran away on their own?" Happens less often than you'd hope. Usually such victims require support from others. "> Anyway the point is there are plenty of situations where you'd want to hide your location but might erroneously think a photo from your window doesn't reveal too much info." I'm sure there might be some fringe examples, but "plenty"? Nobody has yet suggested even one plausible example so far. And even the examples in the article were from people who didn't care about revealing their location to begin with (eg in the first example, the subject announced he was in Miami as well as taking that picture). But I'm sure there are some examples of people stupid enough to share a picture of their location and not realise it might reveal their location to other people; I'm rarely surprised by the stupidity of the worst case scenarios. But I also doubt those sorts of people who lack even that level intelligence would be the kind to people who read articles like these. So whichever way I look at it, I can't see anyone's life saved (metaphorically nor literally) by the research conducted by this author (as interesting as it might be to many of us).

Yardlink 12y ago

I was halfway through the article before I realized it wasn't going to be about a security vulnerability in MS Windows!

alkonaut 12y ago

Point is: when you post a view or a location name that's when you want to tell the world where you are. I'm not inadvertently revealing my location I'm very much advertently revealing it. I assume there are much more creepy techniques to tell where I am when I don't explicitly reveal it.

arrrg 12y ago

Using the reflections as additional information is very interesting. However, I’m not that surprised that views from windows can be relatively easily located. Andrew Sullivan has been running his View From Your Window contest for four years now and people have been guessing the locations of the photos with scary accuracy (as good as in the linked post). Here is the archive: http://dish.andrewsullivan.com/vfyw-contest/ http://dish.andrewsullivan.com/vfyw-contest/ Still, it’s probably more than 15 minutes work even in the best case scenario (and much, much longer in the worst case), can probably not be automated in any meaningful way (but that would be an interesting project, huh!) and is consequently only of interest to dedicated attackers, not general surveillance.

abruzzi 12y ago
And he doesn't even give a starting city or country. His readers have to narrow down the location using street signs, building types, car types, and other subtle hints. So if you don't want people to find you don't post pictures of where you are.
- saraid216 12y ago
  > So if you don't want people to find you don't post pictures of where you are. This cannot be said enough. It's definitely worth educating people to the kinds of things they're exposing when publishing things like vacation photos, but most people shouldn't have a need for that level of information security.

hellbreakslose 12y ago

If you have to hide don't take a picture of where you are at. Also don't check in on fb from that place ;)

return0 12y ago

There is nothing inadvertent here.

mhb 12y ago

Possibly more interesting: Research shows eye-reflections in photos could be used to identify criminals: http://www.engadget.com/2013/12/29/eye-reflections-catch-criminals/ http://www.engadget.com/2013/12/29/eye-reflections-catch-cri...

uptown 12y ago
Dual Photography has always been the optical "trick" that's blown me away. Here's the demo video from Siggraph in 2005: http://www.youtube.com/watch?v=p5_tpq5ejFQ http://www.youtube.com/watch?v=p5_tpq5ejFQ Skip ahead to 4:19 for a succinct demo.

richbradshaw 12y ago

Also, taking photos of meals you are eating can inadvertently reveal your dietary choices. Look at that burger - you can see from the menu that this is a vegetarian restaurant - that means that the 'meat' isn't really meat at all but a bean and nut mixture.

jeroen 12y ago

Views out the window are also very useful for finding the exact location of real estate for sale or rent, when the ad only shows an approximate location.

joewee 12y ago

This only seems useful if it is automated and extremely fast. If you are law enforcement there are faster ways to do this. Like just calling in the city the "bad" guy last checked in at. And if you aren't, there are much easier ways to get info on the room someone is using, like social engineering. Which I'd actually one if the examples the author gave when he simply asked the victim in twitter what floor he/she was on. I haven't seen criminal scenarios where the bad guy takes a photo if his view or checks in on four square, that doesn't get rounded up fairly quickly.

frogpelt 12y ago

My takeaway: if you want to throw creepers like this guy off your trail, harvest a hotel picture from the internet and post it to your Twitter account.

ewindisch 12y ago

As a countermeasure, the article notes turning off lights and so forth. Seems the author hasn't heard of polarized lenses. Others note that it's not a real security concern, no, but using a FLD lens will result in better photos when shooting through glass! Use it!

deleted 12y ago

[deleted]

clarky07 12y ago

So, 99.9% of the information was gathered based on the actual photo, and .1% of it confirmed with reflections. Impressive. Hmm, this picture of a landmark came from the building near the landmark. How did you get that with just reflections?!?

jack-r-abbit 12y ago

I would think a person would be more concerned about other things (not location) being relieved in the reflection. Like the strippers you have in the room. Or the drugs.

jclarkcom 12y ago

From the title of the article I expected this to discuss a computer vision related technique for enhancing the camera location using reflections. Using techniques similar to those in photosythn, you can already determine camera location fairly accurately and easier than the manual work done by the article's author.

malandrew 12y ago

There may come a time when indoor pictures could reveal your location as well. If you were to create a database of lots and lots of architectural plans, you could conceivably use computer vision algorithms for determining dimensions of a room as a few more known bits of entropy for identifying an indoor location.

instaheat 12y ago

Who cares?

JTxt 12y ago

With a set of photos of the same static scene, it's possible to figure out the camera position, angle, and focal length of every camera, sometimes to millimeter accuracy. You just have to correlate the same features in each frame, then solve it. 3d motion trackers do this. (Blender.org has one. You can solve this same problem using it. Bring in public and street view photos of the area. It's a bit of manual work to put all the images in a movie then go frame by frame and tag features... But you could get much more accurate than the article.) The power is in having access to large databases of photos of everywhere, and even better if all the photos were taken the same way, like google's street view... and large amounts of computing resources to index and correlate all of the features from all of the images automatically. I would be surprised if there is not a project in some huge company or lab that can identify features in nearly any public outdoor shot and determine exactly where it was taken. (perhaps for intelligence or forensics) I believe this paper introduced me to the idea in 2006: http://research.microsoft.com/en-us/um/redmond/groups/ivm/phototours/PhotoTourism.pdf http://research.microsoft.com/en-us/um/redmond/groups/ivm/ph...

ilovecookies 12y ago

You might reveal your location but the person spying on you would have to be a stalker and a total creep, who basically have no life and nothing interesting to do. That's more scary than taking pictures with reflections IMO