I do not think the issue is a reversal of lat and lon (but using Y for
longitude is very confusing!). In Romina's example there is a difference
of 10000000 meters in northing. I.e. the number she expected uses a
'false
northing'
Romina used:
"+proj=utm +zone=21 ellps=WGS84"
Piero fixed the problem by using (via an epsg code)
"+proj=utm +zone=21 +south +ellps=WGS84 +datum=WGS84"
note the "+south" to get the false northing.
Robert
On Wed, Jun 6, 2012 at 9:23 AM, Piero Campalani
<piero.campa at gmail.com>wrote:
Hi Romina,
looking at { http://spatialreference.org/ref/epsg/32721/ } I can see
the
UTM zone 21H or also 21S for South spans longitudes in the range
(-80,-60)
so I guess you just inverted easting and northing in your code:
So:
$ LatLong <- data.frame(Y=-35.14189, X=-57.39206) # <-- X is the
LONGITUDE.
$ coordinates(LatLong) <- ~ X+Y
$ proj4string(LatLong) <- CRS("+init=epsg:4326")
$ Utm <- spTransform(LatLong, CRS("+init=epsg:32721"))
$ Utm
SpatialPoints:
X Y
[1,] 464285.6 6111151
Cheers,
Piero
In general anyway, it's safer to identify CRS by EPSG code -- which in
your
case is 32721 (http://spatialreference.org/ref/epsg/32721/) --, then
you
can create it like this:
$ Utm <- spTransform(LatLong, CRS("+init=epsg:32721"))
On 6 June 2012 17:57, <rscardamaglia at ege.fcen.uba.ar> wrote:
Hello,
I need some help transforming Latitude Longitude coordinates (in
degrees) to UTM (zone 21 H, since I?m in Buenos Aires, Argentina).
This is the script I used. The transformation for the easting
is correct but not for the Northing.
LatLong <- data.frame(X = coordenadas2[,1], Y = coordenadas2[,2])
LatLong
X Y
1 -35.14189 -57.39206
2 -35.14072 -57.39421
3 -35.14507 -57.38274
4 -35.14390 -57.39083
5 -35.14496 -57.39312
6 -35.14069 -57.39280
7 -35.14241 -57.39119
coordinates(LatLong) <- ~ Y + X
proj4string(LatLong) <- CRS("+proj=longlat +ellps=WGS84
Utm <- spTransform(LatLong, CRS("+proj=utm +zone=21 ellps=WGS84"))
Utm
SpatialPoints:
Y X
[1,] 464285.6 -3888849
[2,] 464089.3 -3888720
[3,] 465136.0 -3889198
[4,] 464398.6 -3889071
[5,] 464190.4 -3889189
[6,] 464217.7 -3888716
[7,] 464365.1 -3888906
Coordinate Reference System (CRS) arguments: +proj=utm +zone=21
+ellps=WGS84
It seems the Easting coordinates are well transformed, but the
should be around 6111151.35 m S (for the first one for example).
I would really appreciate some help.
Best wishes,
Romina.