Converting coordinates

Question

I'm dealing with a certain problem. I have locations from ArcGIS. For example here are coordinates:

X-Point: 461946,50 Y-Point: 546587,81

Now this should specify a place in Iceland. I understand latitude/longitude but this is a format I'm not familiar with.

Can you see which format this is and how can I convert it to lat/long? Bear in mind that I don't have access to ArcGIS directly, so being able to convert by using a formula or a conversion tool online would be ideal. However I haven't found anything.

I've tried looking at examples of the following formats:

• Decimal degrees (DD)
• Degrees decimal minutes (DDM)
• Degrees-minutes-seconds (DMS)
• Global Area Reference System (GARS)
• GEOREF (World Geographic Reference System)
• Universal Transverse Mercator (UTM)
• United States National Grid (USNG)
• Military Grid Reference System (MGRS)

But none strike me as the correct one.

Answer 1

If you don't know a coordinate system go to http://projfinder.com and put in some coordinates and zoom/pan the map to where you think the point should be (ie Iceland). The system will then scan over the hundreds (thousands?) of possible coordinate systems and show the ones that result in locations nearest your point.

In this case, the nearest system, and the only one in Iceland appears to be "EPSG:3057". This code stands for a specific way of mapping lat-long to those numbers, as a regular grid, valid only around Iceland (because the Earth is not flat, remember). If you have a GIS or programming language that can convert coordinate systems and you want lat-long from these points, you need to do a transform from EPSG:3057 to EPSG:4326, which is the conventional "GPS" lat-long coordinate system (aka "WGS 84").

https://epsg.io/3057 more info about coordinate system EPSG:3057

Answer 2

The format you've shown appears to be a simple Cartesian coordinate system with X and Y values, where the X value represents the east-west position and the Y value represents the north-south position. For Iceland, a common projected coordinate system is the Icelandic Grid (ISN93), which uses meters as the unit of measurement. You can use proj4 or other projection libraries/tools to convert these coordinates to latitude and longitude.