Werner Wernersen
2008-Aug-19 19:28 UTC
[R] converting coordinates from utm to longitude / latitude
Hi, is there a function in R to convert data read with read.shape and which is originally in UTM coordinates into longitude / latitude coordinates? I found the convUL() function from the PBSmapping package but I have no idea how I could apply that to the read.shape object. Many thanks, Werner __________________________________________________ Do sragenden Schutz gegen Massenmails. http://mail.yahoo.com
Werner Wernersen
2008-Aug-19 22:08 UTC
[R] converting coordinates from utm to longitude / latitude
It would be nicer to convert directly the entire shapefile object to long/lat
coordinates but if that is not possible, I will convert the other points to UTM.
Hence, I am playing around with rgdal.
library(rgdal)
SP <- SpatialPoints(cbind(32.29252, -0.3228500),
proj4string=CRS("+proj=longlat"))
spTransform(SP, CRS("+proj=utm +zone=36"))
> spTransform(SP, CRS("+proj=utm +zone=36"))
SpatialPoints:
coords.x1 coords.x2
[1,] 421274.4 -35687.37
Coordinate Reference System (CRS) arguments: +proj=utm +zone=36 +ellps=WGS84
This result corresponds with what I get when using convUL() but my map of that
area in UTM coordinates does not extend to the negative.
An external program converts the point to x=420994 y=9964407 which also seems
correct with respect to the map. Fore sure, I am using the function wrongly
somehow. Can anyone give me a hint?
That's very much appreciated!
Thanks,
Werner
----- Urspr?ngliche Mail ----
Von: Werner Wernersen <pensterfuzzer at yahoo.de>
An: r-help at stat.math.ethz.ch
Gesendet: Dienstag, den 19. August 2008, 20:28:29 Uhr
Betreff: converting coordinates from utm to longitude / latitude
Hi,
is there a function in R to convert data read with read.shape and which is
originally in UTM coordinates into longitude / latitude coordinates?
I found the convUL() function from the PBSmapping package but I have no idea how
I could apply that to the read.shape object.
Many thanks,
Werner
______________________________
f?gt ?ber einen herausragenden Schutz gegen Massenmails.
http://mail.yahoo.com
__________________________________________________
Do
ragenden Schutz gegen Massenmails.
http://mail.yahoo.com
Werner Wernersen
2008-Aug-20 10:04 UTC
[R] converting coordinates from utm to longitude / latitude
You were absolutely right. If I use south everything is fine. That once again proves the danger of intuition. I simply assumed since almost all of the map is on the northern half that the projection should use north as well. But that is apparently wrong. I couldn't find any description of these definition string parameters which could have been informative. Since I am not a geographer either, I probably used the wrong terms for searching. Anyway, now it works. Thanks so much for the help, Jim! Best regards, Werner ----- Urspr?ngliche Mail ---- Von: Jim Regetz <regetz at nceas.ucsb.edu> An: Werner Wernersen <pensterfuzzer at yahoo.de> CC: r-help at stat.math.ethz.ch Gesendet: Mittwoch, den 20. August 2008, 03:08:48 Uhr Betreff: Re: converting coordinates from utm to longitude / latitude Werner Wernersen wrote:> It would be nicer to convert directly the entire shapefile object to long/lat coordinates but if that is not possible, I will convert the other points to UTM. > Hence, I am playing around with rgdal. > > library(rgdal) > SP <- SpatialPoints(cbind(32.29252, -0.3228500), > proj4string=CRS("+proj=longlat")) > spTransform(SP, CRS("+proj=utm +zone=36")) > > >> spTransform(SP, CRS("+proj=utm +zone=36")) > SpatialPoints: > coords.x1 coords.x2 > [1,] 421274.4 -35687.37 > Coordinate Reference System (CRS) arguments: +proj=utm +zone=36 +ellps=WGS84 > > This result corresponds with what I get when using convUL() but my map of that area in UTM coordinates does not extend to the negative. > An external program converts the point to x=420994 y=9964407 which also seems correct with respect to the map. Fore sure, I am using the function wrongly somehow. Can anyone give me a hint?It looks like you are specifying 36S in your external program, and (implicitly) 36N in R. Using your SP from above, note the following:> spTransform(SP, CRS("+proj=utm +zone=36 +north"))SpatialPoints: coords.x1 coords.x2 [1,] 421274.4 -35687.37 Coordinate Reference System (CRS) arguments: +proj=utm +zone=36 +ellps=WGS84> spTransform(SP, CRS("+proj=utm +zone=36 +south"))SpatialPoints: coords.x1 coords.x2 [1,] 421274.4 9964313 Coordinate Reference System (CRS) arguments: +proj=utm +zone=36 +south +ellps=WGS84 The latter gets in the ballpark of output from your external program. I'd speculate that the remaining differences owe to different assumptions about e.g. the datum (WGS84 for the R statements given above), but I must admit I'm not a geographer. Hope that helps, Jim> That's very much appreciated! > > Thanks, > Werner > > > > ----- Urspr?ngliche Mail ---- > Von: Werner Wernersen <pensterfuzzer at yahoo.de> > An: r-help at stat.math.ethz.ch > Gesendet: Dienstag, den 19. August 2008, 20:28:29 Uhr > Betreff: converting coordinates from utm to longitude / latitude > > Hi, > > is there a function in R to convert data read with read.shape and which is originally in UTM coordinates into longitude / latitude coordinates? > I found the convUL() function from the PBSmapping package but I have no idea how I could apply that to the read.shape object. > > Many thanks, > Werner > > > ______________________________ > f?gt ?ber einen herausragenden Schutz gegen Massenmails. > http://mail.yahoo.com > > > __________________________________________________ > Do > ragenden Schutz gegen Massenmails. > http://mail.yahoo.com > > ______________________________________________ > R-help at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. >________________________________________ ber einen herausragenden Schutz gegen Massenmails. http://mail.yahoo.com
Werner Wernersen
2008-Aug-20 10:10 UTC
[R] converting coordinates from utm to longitude / latitude
After having figured out that I had to download the proj.dll file additionally (it would be nice if they actually added a note to their readme) and setting the "+south" parameter, the conversion of the shapfile from UTM to long/lat with the ogr2ogr utility from gdal worked perfectly. Thanks so much Dylan! Werner ----- Urspr?ngliche Mail ---- Von: Dylan Beaudette <dylan.beaudette at gmail.com> An: r-help at r-project.org CC: Werner Wernersen <pensterfuzzer at yahoo.de> Gesendet: Dienstag, den 19. August 2008, 23:29:34 Uhr Betreff: Re: [R] converting coordinates from utm to longitude / latitude If you would like to convert the entire shapfile check out GDAL: http://www.gdal.org/ http://casoilresource.lawr.ucdavis.edu/drupal/node/98 Cheers, Dylan On Tuesday 19 August 2008, Werner Wernersen wrote:> It would be nicer to convert directly the entire shapefile object to > long/lat coordinates but if that is not possible, I will convert the other > points to UTM. Hence, I am playing around with rgdal. > > library(rgdal) > SP <- SpatialPoints(cbind(32.29252, -0.3228500), > proj4string=CRS("+proj=longlat")) > spTransform(SP, CRS("+proj=utm +zone=36")) > > > spTransform(SP, CRS("+proj=utm +zone=36")) > > SpatialPoints: > coords.x1 coords.x2 > [1,] 421274.4 -35687.37 > Coordinate Reference System (CRS) arguments: +proj=utm +zone=36 > +ellps=WGS84 > > This result corresponds with what I get when using convUL() but my map of > that area in UTM coordinates does not extend to the negative. An external > program converts the point to x=420994 y=9964407 which also seems correct > with respect to the map. Fore sure, I am using the function wrongly > somehow. Can anyone give me a hint? > > That's very much appreciated! > > Thanks, > Werner > > > > ----- Urspr?ngliche Mail ---- > Von: Werner Wernersen <pensterfuzzer at yahoo.de> > An: r-help at stat.math.ethz.ch > Gesendet: Dienstag, den 19. August 2008, 20:28:29 Uhr > Betreff: converting coordinates from utm to longitude / latitude > > Hi, > > is there a function in R to convert data read with read.shape and which is > originally in UTM coordinates into longitude / latitude coordinates? I > found the convUL() function from the PBSmapping package but I have no idea > how I could apply that to the read.shape object. > > Many thanks, > Werner > > > ______________________________ > f?gt ?ber einen herausragenden Schutz gegen Massenmails. > http://mail.yahoo.com > > > __________________________________________________ > Do > ragenden Schutz gegen Massenmails. > http://mail.yahoo.com > > ______________________________________________ > R-help at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html and provide commented, minimal, > self-contained, reproducible code.-- Dylan Beaudette Soil Resource Laboratory http://casoilresource.lawr.ucdavis.edu/ University of California at Davis 530.754.7341 __________________________________________________ Do You Yahoo!? Sie sind Massenmails. http://mail.yahoo.com
Werner Wernersen
2008-Aug-20 10:59 UTC
[R] converting coordinates from utm to longitude / latitude
I forgot one more potentially time-saving hint if someone else wants to use org2org for such a conversion: I found that only GDAL for Windows 1.4.4 works together with the proj.dll file which is downloadable from proj.4 but version 1.5 does not. ----- Urspr?ngliche Mail ---- Von: Dylan Beaudette <dylan.beaudette at gmail.com> An: r-help at r-project.org CC: Werner Wernersen <pensterfuzzer at yahoo.de> Gesendet: Dienstag, den 19. August 2008, 23:29:34 Uhr Betreff: Re: [R] converting coordinates from utm to longitude / latitude If you would like to convert the entire shapfile check out GDAL: http://www.gdal.org/ http://casoilresource.lawr.ucdavis.edu/drupal/node/98 Cheers, Dylan On Tuesday 19 August 2008, Werner Wernersen wrote:> It would be nicer to convert directly the entire shapefile object to > long/lat coordinates but if that is not possible, I will convert the other > points to UTM. Hence, I am playing around with rgdal. > > library(rgdal) > SP <- SpatialPoints(cbind(32.29252, -0.3228500), > proj4string=CRS("+proj=longlat")) > spTransform(SP, CRS("+proj=utm +zone=36")) > > > spTransform(SP, CRS("+proj=utm +zone=36")) > > SpatialPoints: > coords.x1 coords.x2 > [1,] 421274.4 -35687.37 > Coordinate Reference System (CRS) arguments: +proj=utm +zone=36 > +ellps=WGS84 > > This result corresponds with what I get when using convUL() but my map of > that area in UTM coordinates does not extend to the negative. An external > program converts the point to x=420994 y=9964407 which also seems correct > with respect to the map. Fore sure, I am using the function wrongly > somehow. Can anyone give me a hint? > > That's very much appreciated! > > Thanks, > Werner > > > > ----- Urspr?ngliche Mail ---- > Von: Werner Wernersen <pensterfuzzer at yahoo.de> > An: r-help at stat.math.ethz.ch > Gesendet: Dienstag, den 19. August 2008, 20:28:29 Uhr > Betreff: converting coordinates from utm to longitude / latitude > > Hi, > > is there a function in R to convert data read with read.shape and which is > originally in UTM coordinates into longitude / latitude coordinates? I > found the convUL() function from the PBSmapping package but I have no idea > how I could apply that to the read.shape object. > > Many thanks, > Werner > > > ______________________________ > f?gt ?ber einen herausragenden Schutz gegen Massenmails. > http://mail.yahoo.com > > > __________________________________________________ > Do > ragenden Schutz gegen Massenmails. > http://mail.yahoo.com > > ______________________________________________ > R-help at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html and provide commented, minimal, > self-contained, reproducible code.-- Dylan Beaudette Soil Resource Laboratory http://casoilresource.lawr.ucdavis.edu/ University of California at Davis 530.754.7341 __________________________________________________ Do You Yahoo!? Sie sind Massenmails. http://mail.yahoo.com