How can I convert local time with long & lat into universal time?

#1

How can I convert local time (with long & lat) into universal time, is there maybe a library for this? The problem seems be be very difficult to solve. I am searching the interwebs now for two days already but to no avail.

Thx in advance and sorry for in the case if its a stupid question …

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#2

I don’t know the answer off the top of my head, but if you google “convert latitude and longitude to timezone” you’ll find a ton of results. Maybe that would be a good place to start?

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#3

What do you need it for, and how accurate do you need it to be?

You could use the geonames API: http://www.geonames.org/export/web-services.html

Or, if some errors are acceptable, you could use a Java library like llttz

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#4

I have been googling this for two full days, I could not find a decent answer.

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#5

Thx, that was the answer I was looking for!
In the mean time I have made my own solution, I made a png map based
on this; https://www.cia.gov/LIBRARY/publications/the-world-factbook/graphics/ref_maps/physical/pdf/standard_time_zones_of_the_world.pdf

when I read the lat/long, I get the timezones.
The map is 5400 by 2761 pixels.

edit; I thought there was an error in my map, but its the data I compared with that was wrong …
Works fine!

Later I can put the code online, but first I want to be sure it works properly (still needs more testing).

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#6

Thanks so much for planning to share you solution with the forum! It sounds interesting and extremely helpful to share.

If you want a polygon-based solution (rather than a web api, or a pixel-based solution), you could also use something like this set of geometry built from OpenStreetMap:

which is wrapped by this Java library:

However this might be an industrial-strength solution that is overkill for your needs – I believe that it has a relatively big footprint and long load time.

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