Dear all, I have tried to transform coordinates from UTM Zone-31 ED-50 Spain Portugal (EUR-D code in this web http://earth-info.nga.mil/GandG/coordsys/onlinedatum/CountryEuropeTable.html # EURD) to coordinates WSG84 ( google maps coordinates) with the "ptransform" of the proj4 library and I can not do it right (first syntax). I have tried also using the "spTransform" of the rgdal library (second syntax) and I have not been successful. I attach the syntax used, I got 4 points with coordinates ED ESP-50 ( "utm" in the syntax) and their respective coordinates WSG84 (wgs.gold "in the syntax). Can anyone tell me where is the error? Thank you very much, Marc
#First sintax library(proj4) x.utm <- c(428727134,431587743,434639340,426268557) y.utm <- c(4584118048,4581465377,4584855001,4584607449) x.wgs <- c(41.4036923115558,41.38010926480547,41.41148169051035,41.409534433320914) y.wgs <- c(2.145810127258301,2.1807003021240234,2.2183799743652344,2.1170568466186523) utm <- cbind(x.utm, y.utm) wgs.new <- ptransform(utm, "+proj=utm +ellps=intl +zone=31 +towgs84=-84,-107,-120,0,0,0,0,0 +no_defs",
+ "+proj=latlong +datum=WGS84")
wgs.new
[,1] [,2] [,3] [1,] -2.236353 1.570775 39.63333 [2,] -2.236353 1.570775 39.63333 [3,] -2.236353 1.570775 39.63333 [4,] -2.236353 1.570775 39.63333
(wgs.gold <- cbind(x.wgs, y.wgs))
x.wgs y.wgs [1,] 41.40369 2.145810 [2,] 41.38011 2.180700 [3,] 41.41148 2.218380 [4,] 41.40953 2.117057
#Second sintax library(rgdal) (data.utm <- data.frame(x.utm,y.utm,x.wgs,y.wgs))
x.utm y.utm x.wgs y.wgs 1 428727134 4584118048 41.40369 2.145810 2 431587743 4581465377 41.38011 2.180700 3 434639340 4584855001 41.41148 2.218380 4 426268557 4584607449 41.40953 2.117057
coordinates(data.utm) <- c("x.utm", "y.utm")
proj4string(data.utm) <- CRS("+proj=utm +ellps=intl +zone=31 +towgs84=-84,-107,-120,0,0,0,0,0 +no_defs")
(wgs.new2 <- spTransform(data.utm, CRS("+proj=latlong +datum=WGS84")))
coordinates x.wgs y.wgs 1 (-128.134, 89.9988) 41.40369 2.145810 2 (-128.134, 89.9988) 41.38011 2.180700 3 (-128.134, 89.9988) 41.41148 2.218380 4 (-128.134, 89.9988) 41.40953 2.117057 2009/3/23 Paul Hiemstra <p.hiemstra at geo.uu.nl>
Hi, To transform coordinates you can use the spTransform function from the rgdal pacakge. It uses proj4 to do the transformations. Proj uses a string to describe a certain projection, the so called proj4string. If you can determine the proj4string for both your projections you can transform between them. The first string (WGS84) looks like this: "+proj=longlat +datum=WGS84" The second (UTM) something like: "+proj=utm +zone=yourzone +datum=yourdatum" See the documentation of spTransform for more information on how to use the function. cheers and hth, Paul Marc Mar? Dell'Olmo wrote:
Dear R-users, Can anyone tell me how to convert point coordinates from WSG84 (google maps coordinates) format to UTM HUSO-31 ED-50. And if I have a map (shp format) with UTM HUSO-31 ED-50 coordinates, how can I convert to WSG84 (google maps coordinates) coordinates. Should I install some external software? Can anyone tell me the instructions? Thank you, Marc
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