[R-sig-Geo] Proj4 natgrid coordinate transformation error

Jonas Schmedtmann jonasschmedtmann_23 at hotmail.com
Mon Mar 24 12:49:53 CET 2014

Hi everyone,
I’m trying to use the nadgird parameter for coordinate transformation from the portuguese Hayford Gauss IGeoE system to UTM 29 WGS84 used in Landsat images for Portugal. I have the following code, which produces an error, so I wonder if I got everything right in my proj4strings. I’ve tried a lot of things, and an intensive google search did not solve my problem either. I got the file 'ptLX_e89.gsb’ from a professor of mine so I assume there’s nothing wrong with it.

> PROJ4_IGEOE<-CRS("+proj=tmerc +lat_0=39.66666666666666 +lon_0=-8.131906111111112 +k=1 +x_0=200000 +y_0=300000 +ellps=intl +units=m +nadgrids=ptLX_e89.gsb +wktext +no_defs")
> PROJ4_UTM<-CRS("+proj=utm +zone=29 +ellps=WGS84 +datum=WGS84 +units=m")
> area<-readShapePoly("../01 Dados/02 Dados espaciais/AREA_ESTUDO", proj4string=PROJ4_IGEOE)
> area_wgs84<-spTransform(area, PROJ4_UTM)
Error in .spTransform_Polygon(input[[i]], to_args = to_args, from_args = from_args,  : 
  error in pj_transform: failed to load datum shift file

I’d appreciate any help. Thanks in advance!
Jonas Schmedtmann

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