[R-sig-Geo] Converting State Plane Coordinates

Jonathan Marc Bearak jonathan.bearak at nyu.edu
Tue Aug 24 16:51:57 CEST 2010


I'm new to GIS and have been trying to convert latitude and longitude to/from state plane coordinates.

I've tried using the project() program from the proj4 library to convert lat/lng to FIPS 3104 (New York State Long Island).

No matter how I go about this, however, the coordinates come out wrong.  E.g., 
		  	"+proj=lcc +lat_1=40.66666666666666 +lat_2=41.03333333333333 +lat_0=40.16666666666666 +lon_0=-74 +x_0=300000 +y_0=0 +units=ft +no_defs +datum=NAD83",
		  	"+proj=lcc +a=6378137 +es=.0066943800229 +lon_0=-74 +lat_1=41d2 +lat_2=40d40 +lat_0=40d10 +x_0=300000 +y_0=0 +units=ft +no_defs +datum=NAD83", 

E.g., if I try the inverse, to convert 1062791, 209606.6 to lat/lng, project() prints:  43.04762 -76.89626.  The correct coordinates, however, are: 40.7416495 -073.7165681.

I've been reading the mailing lists and searching Google and R project PDFs and manual pages without any luck for an embarrassingly long number of hours without any luck.

Thanks for any help.


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