I'm working in C# and I have this JSON:

{"id":429,"name":null,"address":"10 Wooleys La.",
"city":"Great Neck", "decadeBlt":0,"totalUnits":12,"propertyType":null,
"wkt":"POIN‌​T (-8207941 4982429)"}

I need to get the WGS84 latitude and longitude of this point (it's in Long Island, NY).

  • 1
    It might help if you tell where on the earth this place is. – user30184 Jan 19 '18 at 17:33
  • Could be DDMMSS.S or DDMM.MMM if they are lat/long... But could be another kind of reference system. Knowing the app. place would help a lot – aldo_tapia Jan 19 '18 at 18:06
  • 1
    Let me see if I understood your question - you have a coordinate pair in an unknown projection, for which you want the lat/lon values? – Roberto Ribeiro Jan 19 '18 at 18:56
  • The coordinates are in EPSG::3857, AKA "Web Mercator". – mkennedy Jan 22 '18 at 17:55

By checking the reported coordinates and location using ArcGIS (ArcMap specifically), I was able to identify these coordinates:

POIN‌​T (-8207941 4982429)

as being in EPSG::3857. Colloquially called Web Mercator, its EPSG name is "WGS 84 / Pseudo-Mercator". The EPSG geodetic parameter registry is a large repository of coordinate reference systems and transformations.

It uses a spherical Mercator algorithm with a radius of 6378137.0 m. If you unproject the coordinates to latitude-longitude, they'll automatically be on WGS 84 (EPSG::4326).

The coordinates are in easting (X), northing (Y) order.

Disclosure: I'm a member of the subcommittee that maintains the EPSG registry.

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