[R] Easting and northing cf. Latitude and longitude

[White.Denis@epamail.epa.gov]

As Ted Harding suggested in an earlier reply, the conversions can be
complicated.  Most GPS units provide both geodetic coordinates (latitude,
longitude) and coordinates in the Universal Transverse Mercator projection
(northings and eastings in meters).  See the r-help thread on "map
projections" between 20 April and 23 April 2001.  Also see public domain
software available at http://mapping.usgs.gov/www/html/cartsoft.html.  For
background on map projections try a web search, e.g.
http://www.colorado.edu/geography/gcraft/notes/mapproj/mapproj_f.html.

Denis White
   US EPA, 200 SW 35th St, Corvallis, Oregon, 97333 USA
   voice: 541.754.4476, email: white.denis at epa.gov
   web: www.epa.gov/wed/pages/staff/white/



                                                                                          
                    Patrick Connolly                                                      
                    <P.Connolly at hortresea        To:     r-help at stat.math.ethz.ch         
                    rch.co.nz>                   (R-help)                                 
                    Sent by:                     cc:                                      
                    owner-r-help at stat.mat        Subject:     [R] Easting and northing    
                    h.ethz.ch                    cf. Latitude and longitude               
                                                                                          
                                                                                          
                    06/21/2001 21:47                                                      
                    Please respond to                                                     
                    Patrick Connolly                                                      
                                                                                          
                                                                                          




I think I've seen this discussed here before but it doesn't seem to
appear in the archive.

I am using the map package which so far has been fine for my purposes.
Some people I work with have GPS type data that defines positions as
number of metres not degrees.  I don't know how much the system
varies, but in New Zealand, they are referred to as Eastings and
Northings.

What I would like to know is how complicated it is to convert between
such data and the normal latitude and longitude that the map package
uses.  I assume various datum points are used for different parts of
the world, and knowing the appropriate one and the definition of a
"northing" and an "easting", the conversion would be relatively
straight forward.

TIA




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Patrick Connolly
HortResearch                        Great minds discuss ideas;
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Auckland                            Small minds discuss people.
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