[GRASS5] datum transforms...

[Frank Warmerdam]

Paul Kelly wrote:
> An alternative idea I had came from some hints in a note by Frank
> Warmerdam (http://remotesensing.org/lists/proj_archive/msg00162.html) on
> use of the proj library: modify pj_open_lib.c to tell it where to
> search for the files. I feel this would be acceptable as GRASS is already
> using a modified version of the proj library anyway.
> 
> Looking at that file I see as well as getting the location from an
> environment variable PROJ_LIB, another option is to have PROJ_LIB
> #define'd somewhere in the source code. But as it varies depending on the
> installation I don't think that would be possible (or is it?). I propose a
> small change something like the following:

Paul / Eric,

I would prefer to see GRASS use the pj_set_finder() function to install a
function to find PROJ support files.  This finder function would form the
path to the PROJ files within the GRASS tree using methods similar to what
you use to set the PROJ_LIB now.

This is the preferred manner for applications to control the searching for
PROJ.4 support files.  Let me know if you would like details on how to
accomplish this.

I would prefer to keep GRASS changes to PROJ.4 to a minimum so that upgrades
are easy.  As always, I am willing to consider upstream changes to reduce the
need for GRASS to directly modify the PROJ.4 source.

Best regards,

-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent