[Proj] "Double Ellipsoid" error, reproduction

Gerald I. Evenden geraldi.evenden at gmail.com
Wed Dec 10 11:00:43 EST 2008

On Tuesday 09 December 2008 10:53:10 pm you wrote:
> On Tue, Dec 9, 2008 at 7:51 PM, Gerald I. Evenden
> <geraldi.evenden at gmail.com> wrote:
> > On Monday 08 December 2008 4:35:50 pm Richard Greenwood wrote:
> Gerald,
> I have been using Proj.4 and following this list for long enough to
> know your interest in, and contributions to, this project. I have
> enough gray hair to remember the USSR and to be able to use with UNIX
> pipes. I can relate to your frustration, but I can not sympathize with
> it.
> We have moved beyond paper maps and can no longer segregate
> cartography from geodesy - projections from datums. The addition of
> datum support was necessary and well intentioned. The implementation
> was probably imperfect.

You have, for the most part, missed my point entirely.  First, part of the 
effect of treating the problem as a combination is poor software practice and 
leads to unnecessary complexity in software development and maintenance.

Secondly, just because overview of dealing with the existing state of 
coordinate systems necessitates dealing with both datums *and* projections 
does not mean that datums and projections are in and of themselvese 
connected; they obviously are not.  Their only connection is being one of the 
many individual elements of the issue.  Is the math library to be hacked into 
pieces to facilitate tangent's use in this problem?  Do we change tangent 
software in the same manner as pj_init because tangent is used in doing grid 
system problems?

Also, this seemingly devinely designated datum-projection combination attitude 
may stiffle improvement of grids where use of alternate projections may be 
more desirable; not that anyone here has control over this decision. ;-)

> Perfecting the implementation of Proj.4 as a comprehensive _coordinate
> system_ library (not just a projection library) without a major
> rewrite is not likely. Restricting it to just a projection library
> would diminish its value to such an extent that it would lose its
> relevance.

The basic concept underlying 'Proj.4' is not wrong; just the implementation.  
Also it would have been a good idea to not use the name 'Proj.4' because it 
is much more than a "projection" package.

> Respectively yours,
> Rich

The whole religious complexion of the modern world is due
to the absence from Jerusalem of a lunatic asylum.
-- Havelock Ellis (1859-1939) British psychologist

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