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Comment by _mulder_ | Hacker News Reader

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.

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Yep, pretty much. The article's neat, but isn't the point of the kind of pictures shown in this article to show where you are? I don't think you can call this "inadvertently".

This is a bit like checking in with Foursquare. If there's a security concern with showing it real-time and net-wide, then you just shouldn't.

Reminded me of this: https://pbs.twimg.com/media/Bm1gMRUCIAA8Y4E.jpg

I think they point is that people would be surprised that you can relatively easily narrow down a vague picture to almost a floor / room number level.

I'm guessing some people may not be comfortable with that.

You're not going to figure out the room number based on what lamp is in the room.

Not from the lamp, from the geometry.

he narrowed it down to like a 4 floor level. who cares? and pretty much none of that information came from the reflections, just the picture itself.

Actually an interesting solution to the Foursquare check-in privacy issue that I've seen is people check in when they are leaving instead of arriving.

This may be a dumb question, what is the value in checking in when leaving? I might not understand the point of foursquare, I thought the check-ins were used so people could meet up with friends who were in the area.

Are there rewards or incentives for checking in or is it for social prestige by being in the right places at the right time? Something else I'm not thinking of?

When you check-in on arrival, that can cause two problems; one, people (whom you don't want to meet) can come to the location to find/meet/stalk/harass you; and two, people know that you're there and not somewhere else (so they know your car/house/office/dog is potentially unguarded).

You can use checkins (especially those of Instagram or Foursquare addicts) to determine someone's pattern; if they always go to Starbucks in the morning for a snack, then go for a run for 30 minutes, then hit the grocery store on the way back, you can figure you probably have 45 minutes to loot their house, search their stuff, etc. before they get back. If you've seen the inside of their house before, you might know that there are spare keys, or a rarely-used door that you can unlock, etc. which gives you more access to the house later, even if your timeframe is limited.

Etc. etc.

Anyway, checking in as you leave throws off that timetable. People can't come meet you (because you're already gone), and you won't tell people you're out of the house until later, cutting down on their window of opportunity.

I understand the problems with checking-in as you go places. What I don't understand is the value in checking in as you leave. Why publish a check-in at all? What do users gain by checking-in?

Assuming that someone is familiar with the location, of course. Also, many times people want to post the view, how many times are they tweeting their hotel and room addresses?

One could use these (and other) techniques to pinpoint your location from anywhere in the globe, without even setting foot in that location, perhaps not even the country.

Keep in mind that the poster "eyeballed" the floor height. With more work, it is possible that he could have figured out not only the floor, but which window the picture was taken from.

Also, nice call on reflections of safes and notebooks.

But none of the information gained from the reflections were not obtainable in another way. In the first example with this image http://4.bp.blogspot.com/-G-MF-A05uSs/U2CA_n8IKfI/AAAAAAAAAZ... He claims it could be three possible hotels from that area. Yet it can actually only be one because there is only one hotel on that side of the road (you can see the road below). I went from that picture I just posted to the actual location without reading the rest of the blog. I have never stepped foot or even seen a photo of Miami. Those buildings are extremely unique. Once I found those buildings, I moved the view around in Google Maps to get me the EXACT point of reference which could have been two different hotels. but Like I said, only one on the correct side of the street.

On the second example, I was able to locate the picture simply by Google Maps. There aren't many buildings with domes on the top of it that is basically right next to water. It took me 3 minutes. Once I found it, I lined up the shot and found the building. There was only one it could have been. With a quick google search. To find which floor the picture was taken on, all I had to do was find which floor was completely straight in the photo (which means he was leveled with that floor) and then translate that height to the other building (by guessing). I guessed floor 17 which was one off and was the exact same guess as the blogger.

Basically, the blog post makes it seem he uses reflections to find where buildings were. In reality the reflections were not useful to locate the building, only to find interior shots after the location is discovered.

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."

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.

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....

Think beyond the work-safe examples and imagine forensic uses. Children being traffiked and abused in hotel rooms would be one example.

Situations where criminal activity took place would usually include police (with child trafficking, more likely even the FBI). To think these ideas or photo analysis techniques are new to LE is naive.

I suspect child abusers generally move out of their landmark hotel room before sharing compromising pictures on the internet (and generally hang around in much less high-profile locations, for obvious reasons). Admittedly it would be a lot more forensically useful if the image had accurate metadata showing date taken.

I was hoping for something clever involving algorithms picking up subtle reflections that weren't visible to the naked eye and or algorithms automagically matching photos with other photos taken from similar angles, but this is Google-fu 101. If you tell people which city you're in and post a photo of the centre, people will probably be able to figure out where it was taken from. That applied long before the age of the internet and digital photography.

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.

I stopped reading when I saw the Vancouver photo. I mean, you probably know exactly where that is even if all you've done is fly over Vancouver, let alone been downtown a couple times.

if they post on Twitter, probably they want you to know they are in some fancy hotel. And if you know the skyline very well, you can deduce which one.

What is really good here is that he went through all the steps in the deduction. Most people will not take the time or patience to pick the landmarks and do the perspective.

As for the article, I didn't know Google Earth was so extensive and I learned some interesting geologic features of Miami!

I thought it was cool detective work and proved a good point, despite not being "particularly ingenious".

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