[R-sig-Geo] Converting State Plane Coordinates

[Roger Bivand]

On Tue, 24 Aug 2010, Alexandre Villers wrote:

> Hey,
>
> There is an ESRI code (ESRI:102318 
> <http://spatialreference.org/ref/esri/102318/>) corresponding to the 
> requested projection... However, I doubt CRS will take an ESRI code (Roger 
> ?).

CRS("+init=esri:102318")

but the ESRI version doesn't give a +datum=, so WGS84 will be assumed. The 
difference is the reversal of the +lat1= and +lat2= values, so probably 
not drastic.

Roger

> Jonathan, have a look at the rgdal and sp packages help pages for the "How 
> To" in CRS()
>
> Best regards
>
> Alex
>
> Le 24/08/2010 17:58, Roger Bivand a écrit :
>> 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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>>>> R-sig-Geo at stat.math.ethz.ch
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>>>> 
>>> 
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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