[R-sig-Geo] Converting State Plane Coordinates

[Roger Bivand]

On Tue, 24 Aug 2010, Alexandre Villers wrote:

> Hello,
>
> Have a look at spTransform (in rgdal package) and the EPSG code of the 
> desired projection (this is to me the easiest way not to mess with digits and 
> various copy errors that can be made while writing the projection properties) 
> at www.spatialreference.org
>
> then, you just have to do something like this
>
> library(rgdal)
>
> data<-read.table ("mydata.txt", h=T, sep=",") #your original dataset
> coordinates(data)<-~ X + Y # where X and Y stand for the name of your lat/lon 
> columns
> proj4string(data)<-CRS("+init=epsg:4326")  #if your coordinates are in WGS84
> data.proj<-spTransfrom(data, 
> CRS("+init=epsg:the.correct.epsg.number.of.your.projection")

Looks like:

http://spatialreference.org/ref/epsg/32118/

but has some different parameters. Search on "New York" in this site for 
alternatives.

Roger

>
> HTH
>
> Alex
>
>
> Le 24/08/2010 16:51, Jonathan Marc Bearak a écrit :
>> Hi,
>> 
>> 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.
>> 
>> Best,
>> Jonathan
>> _______________________________________________
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>> 
>
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-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand at nhh.no