[Proj] datum matters

Noel Zinn ndzinn at comcast.net
Sun Mar 29 15:45:42 EST 2009

Fictitious datum?  That's offensive, daan.  When the datum is ignored,
cartography is an entertainment merely purporting to represent the real
world.  That's fine, but (the) datum is hardly fictitious.  -Noel



From: proj-bounces at lists.maptools.org
[mailto:proj-bounces at lists.maptools.org] On Behalf Of strebe
Sent: Sunday, March 29, 2009 2:15 PM
To: PROJ.4 and general Projections Discussions
Subject: Re: [Proj] datum matters


On Mar 29, 2009, at 9:10:46 AM, "Richard Greenwood"
<richard.greenwood at gmail.com> wrote:

The "computational burden" of comparing the input and output datum is
no more intensive than converting from radians to degrees.


But this is quite my point about misplaced conceptual burdens. Many people
do not even have datums attached to their cartographic data because the
datum is irrelevant at the scale they are working.. What is the use of
forcing them  to declare a fictitious datum in order to satisfy an
ideological conflation of datum and projection?


you will not argue that we limit ourselves to radians. The "conceptual
burden" is more subjective, but closer to my point: That to a growing
number of users, datum does matter.

The number may be growing, but they will never be even close to everyone. I
do not agree everyone should be forced into artificial procedures in order
to save some fraction of them from their own ignorance. That is arrogance,
if nothing else. No one knows what is best for everyone. Datum and
projection are distinct. Let those who need to treat them distinctly, treat
them distinctly. Let those who may or must ignore datums, ignore datums.



- daan Strebe


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