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

[Gerald Evenden]

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

The reason for this is twofold: 1) projections have uses that do not 
involve
datums and their is no reason to burden these uses with elements that 
are
not involved and 2) developers often only have expertise in only one of 
the
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 
datum
manipulation software by including the 'nad2nad' program with the 
initial
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 
projections
(~135 total)  than the Remotesensing version including some newly 
supported
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 
versions.

_____________________________________
Jerry and the low riders: Daisy Mae and Joshua