[GRASS5] Problem converting NAD27 to NAD83 - missing ntv1_can.dat

Craig Funk funkmeister at lynxseismicdata.com
Thu Apr 7 14:40:13 EDT 2005

> The most common cause for that error is that the points you are trying 
> to re-project fall outside the area covered by the datum shift grid 
> file (ntv1_can.dat). Are you sure it is the correct file for your area 
> (Canada).
> If you are having trouble with the grid shift files you could try 
> doing a less precise datum transformation using a 3 or 7-parameter 
> transformation. Re-run g.setproj in the NAD27 location to set up your 
> datum parameters.
> Paul
Thanks Paul,

It ends up that the ntv1_can.dat file did not appear to be installed 
properly. Where should the file live? I placed it in etc/nad directory 
of the GRASS installation and then the r.proj and v.proj commands 
worked fine.

I built my GRASS install from source on a Mac G5. Is this maybe a 
problem with the makefiles?


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