On Thu, 6 Sep 2007, Monica Pisica wrote:
Hi,
Doing more search i've discovered package RGDAL that can write a geotiff
file with projection. I saved a geotiff file in UTM projection and if i
read the file back in R and check the projection seems that everything
is OK. But if i load the file in ArcGIS (ESRI product) i get the warning
that the file is missing spatial reference so it cannot be projected,
but it is displayed correctly. I guess somewhere i am doing a mistake
when i define the projection in R. My code follows:
data.grid - read.csv(x, header=TRUE)
gridded(data.grid) = ~East.m.+North.m.
proj4string(data.grid) = CRS(+proj=tmerc +lat_0=0.000
+lon_0=-81.000 +k=0.9996 +x_0=50.00 +y_0=0.000
+ellps=GRS80 +units=m)
tr - e:\\JELA_veg\\test_gtiff\\test.tif
writeGDAL(data.grid[class.pca], tr)
mg3 - readGDAL(tr)
proj4string(mg3)
[1] +proj=utm +zone=17 +ellps=GRS80 +units=m +no_defs
I will really appreciate if anybody can point me in the right dirrection.
In my previous reply, I suggested that you visit:
http://www.gdal.org/frmt_gtiff.html
There you will find that for ESRI products, you may need to set
options=TFW=YES at least, because ESRI products do not honour the
projection information already encoded inside the GTiff file. The
information is there, it is just that ESRI products only look for it in
places they have thought of, not in the proper places. If necessary,
showWKT() can make a *.prj file. Otherwise just override ESRI.
Roger
Thanks,
Monica
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