[Proj] Re: [kergis_bugs] Re: What proj library version is best?

Gerald Evenden gerald.evenden at verizon.net
Mon Jul 5 20:00:11 EDT 2004

This discussion reminds me of the email interaction Frank Warmerdam and 
had about what should be included in a projection library.  My position 
and still is, that *only* the projection (conversion between geographic 
cartesian space) is the domain of the library.  All non-projection 
elements like
datum shifts and  x-y-z transformations are separate and unrelated 
and belong in their own library systems.

The reason for this is twofold: 1) projections have uses that do not 
datums and their is no reason to burden these uses with elements that 
not involved and 2) developers often only have expertise in only one of 
areas and should not have to burden themselves with library maintenance
involving unfamiliar elements.

I may be partly to blame for the tendency to combine projection and 
manipulation software by including the 'nad2nad' program with the 
PROJ.4 distributions.  But this was included as an example of how to use
the projection library and used by our local shop for datum operations.

I believe Frank and I did reach a consensus but he has not had time to
redo Remotesensing software to conform to the more recent libproj4
that I support.  The last I checked, libproj4 has several more 
(~135 total)  than the Remotesensing version including some newly 
grid systems.

I believe a great deal of the apparent current chaos could have been
avoided by maintaining pristine PROJ.4 libraries and not indulging in
parochial additions that diminish the ease of the importing of later 

Jerry and the low riders: Daisy Mae and Joshua

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