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Canot convert coordinates for lack of known coordinate system

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  • Canot convert coordinates for lack of known coordinate system

    Hi. I have coordinates that someone else collected for me. I need to convert it to a meaningful value that I can map (it's one of about 25 similar coordinates). For other coordinates I have used Lat/Long (degrees, minutes, seconds). One of the values the colleague gave me is (exactly as given to me): 340210 E 2105771 N. The collector of this datum knows nothing about the standard used!!!

    I know the coordinate corresponds to a location within a few hundred meters of the peak of Loma Casabito in the Dominican Republic. Therefore, I would expect a Latitude/Longitude close to 19 2'N 7031'W (though more detailed), which is an approximation of a known location near to the same peak (for simplification, part minutes and seconds have been removed).

    For a different mountain (Loma Barbacoa), I have been told that 358516 E 2041180 N is equivalent to or within a few meters of 1827'21.97" but even knowing this has not helped me find out the original coordinate standard used or the means of converting it to Lat/Long.

    I have tried converting the original coordinates with Google Earth and several online conversion sites. However, some simply don't make a conversion while others do but to Lat/Long values that make no sense at all (completely in the wrong part of the world).

    If there's anyone who recognises the standard being used and can tell me it or who can advise on how to go about getting a conversion, thanks in advance for any info or suggestions.
    Last edited by paulindr; 10-04-2018, 08:37 PM.

  • #2
    I posted the original request for help in good faith. However, someone has quite unexpectedly provided the solution via a different channel. The standard of the coords is ED50 (UTM) and I also got told I needed a region code, that I googled and it turned out to be 19N (Dominican republic). I then tried a conversion site that for some reason failed before finding www.engineeringtoolbox.com. This site proved to be very simple and gave an instant perfect conversion. So, problem solved! Hope this explanation might prove helpful to someone.

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    • #3
      Glad you already found the answer. However, a few more facts to help anyone else with a similar problem.

      The coordinates given are Universal Transverse Mercator (UTM) coordinates in meters. UTM computes rectilinear coordinates over a portion of the earth, This can only have reasonable accuracy over a narrow band (3) over a central meridian. The zone edges are multiples of 6 of longitude. You have to know what zone you are in to properly interpret the easting. A false origin is used so that 500 000 m of easting is the zone center, but the coordinate repeats every 6 of longitude as zone number changes. The northing in meters north of the equator in the northern hemisphere. In the southern hemisphere, a false origin will be used so the equator is 10 000 000 m.

      Unfortunately, the latitude and longitude of the place can also vary slightly with the earth model (datum) used for the map. The USGS offers an excellent converter for lat/long to and from UTM, but only for the two main North American datums NAD27 and NAD83. However, in general, you need to know the map datum, and find a converter that has the proper equation parameters for that datum.

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