How accurate can your position be calculated from a photo of the sun you post online?

Submitted ⁨⁨2⁩ ⁨days⁩ ago⁩ by ⁨nitroemdash@lemmy.wtf⁩ to ⁨[deleted]⁩

Imagine you are a popular content creator on PixelFed, many followers, but many stalkers also. You don’t want people to know where you live. One day you post a picture of the sun out of your window. Exact time is attached in metadata. Assuming GPS metadata is stripped, can someone, using inclination of the sun to the horizon, Nautical Almanac and some math calculate your latitude and/or longitude, and to what precision? Assuming also meteorological data archives on cloudiness, etc.

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dhork@lemmy.world ⁨2⁩ ⁨days⁩ ago
Latitude can theoretically determined by the data in your picture. Longitude is much harder, because you can’t really tell how far east and west you are based on the angle of the sun alone. This was a historic problem, especially when mankind started traveling across oceans.

The problem can be solved by knowing your time relative to some reference point. This is how Greenwich Observatory became so important to timekeeping: to determine longitude, ships had to carry a good clock that showed them what time it was at Greenwich, and the difference in time between when the sun was directly overhead on the ship and noon at Greenwich told them their longitude.

So, the main piece of information that gives away your latitude is actually the time, assuming it is either stored as UTC or as local time with a UTC offset…

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PapaSkwat@lemmy.today ⁨1⁩ ⁨day⁩ ago
Which is why I post pics of places that I’m not really at and that I’ve never personally taken. I have a lemmy stalker who’s pretty persistent, and I love randomly planting fake personal asides in my texts so the incel has no idea where I really am. Like this morning when I took a stroll along the riverfront and posted some pics of my nice peaceful walk.

And he always falls for it and tries to say he knows where I am while dropping hints about me and shit. Dude isn’t even right about he country I’m in or what nationality I am. Winding him up with so many false clues is kinda fun for me. LMAO

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yesman@lemmy.world ⁨2⁩ ⁨days⁩ ago
There was once a Japanese celebrity who’s stalker was able to find out her location by a street sign that was reflected in her eye. You don’t need an astrolabe to be a creep.

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Flax_vert@feddit.uk ⁨2⁩ ⁨days⁩ ago
Buildings would be easier. I triangulated a dude’s position once in istanbul from a photo of his balcony

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- Shellofbiomatter@lemmus.org ⁨2⁩ ⁨days⁩ ago
  I’ll just add that to the list of why i never take pictures and much less upload the rare few i have been forced to take.
  
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slazer2au@lemmy.world ⁨2⁩ ⁨days⁩ ago
They can get a good idea, but more likely they will use other things in the background like trees and buildings.

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Zwuzelmaus@feddit.org ⁨2⁩ ⁨days⁩ ago
It all depends on the land in the picture.

If there were only sky and sun, nobody knows direction or height or place.

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AbouBenAdhem@lemmy.world ⁨2⁩ ⁨days⁩ ago
At any given moment there’s a full circle of points on the surface of the earth at which the sun has the same given zenith angle. So without any other information, the best you could do is narrow it down to someplace on such a circle.

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- Shellofbiomatter@lemmus.org ⁨2⁩ ⁨days⁩ ago
  But then come in the geolocators and based on other clues will figure out the exact location, probably within few minutes.
  
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  - AbouBenAdhem@lemmy.world ⁨2⁩ ⁨days⁩ ago
    A correct guess isn’t usually based on a single clue, but on using multiple clues to narrow the possibilities down in different ways. So every potential clue matters and should be considered, instead of assuming it’s irrelevant because there are other clues present as well.
    
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tyler@programming.dev ⁨2⁩ ⁨days⁩ ago
…research.google.com/…/ShadowFinderColab.ipynb

youtu.be/pQIjDPFgdJA

So pretty accurately, if somebody wants they can find your house.

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gedaliyah@lemmy.world ⁨2⁩ ⁨days⁩ ago
In this example, where only the sun is pictured in relation to an indoor window, and no other information is present, it would be very difficult to make any kind of meaningful calculation. You could probably identify some information about the camera based on the proportion of the disk of the sun, but unless you had some additional information, such as the precise dimensions/compass direction of the window, or the location of the horizon, It would be impossible to make a calculation of this type. There just isn’t enough information.

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