# How do I convert from NAD 83 State Plane Coordinates to Latitude and Longitude?

I am trying to convert NAD 83 State Plane New York Long Island coordinates to Latitude/longitude. Below is my code - what am I doing wrong?

LatitudeLongitude[GeoPosition[{172248, 1002321, 0}, "SPCS83NY04"]]

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Use GeodesyData["Datum"] for a list of available named datums. – Dr. belisarius Nov 25 '13 at 3:18
Cross posted here community.wolfram.com/groups/-/m/t/… – Dr. belisarius Nov 25 '13 at 3:49

## 1 Answer

This seems to work:

LatitudeLongitude @ GeoGridPosition[{172248, 1002321, 0}, "SPCS83NY04"]
(* {49.145, -75.732} *)

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Good one. I delete my answer. +1 – halirutan Nov 25 '13 at 6:00
That does work! What's weird is I used ArcGIS to calculate Lat/Long from the same set of coordinates, and I got 40.639439, -73.9349 instead. Do you have any idea why that might be the case? – jackie Nov 25 '13 at 17:24
This is the projection info for the same datapoint in ArcGIS: Projected Coordinate System: NAD_1983_StatePlane_New_York_Long_Island_FIPS_3104_Feet Projection: Lambert_Conformal_Conic False_Easting: 984250.00000000 False_Northing: 0.00000000 Central_Meridian: -74.00000000 Standard_Parallel_1: 40.66666667 Standard_Parallel_2: 41.03333333 Latitude_Of_Origin: 40.16666667 Linear Unit: Foot_US Geographic Coordinate System: GCS_North_American_1983 Datum: D_North_American_1983 Prime Meridian: Greenwich Angular Unit: Degree – jackie Nov 25 '13 at 17:24
@jackie Could be the units, feet instead of meters? It's a big difference. – Michael E2 Nov 25 '13 at 19:07
Thanks Michael! That turned out to be the issue, and I got the same answer as the GIS application. Do you understand why GeoGridPosition has to be used insted of GeoPosition - is it because State Plane is a projected coordinate system rather than a geographic one? THANKS AGAIN! – jackie Nov 25 '13 at 21:33