[OSRS-PROJ] Prime Meridian Support in PROJ.4

Frank Warmerdam warmerdam at pobox.com
Thu Oct 3 16:04:54 EDT 2002

Gerald Evenden wrote:
> Just as an aside from the original author of proj.4:  prime meridian has no place
> in proj.4.  Any offsets in longitude due to variations in coordinate system "prime
> meridian" should be taken care of externally with adjustments to "lon_0"
> parameter.


Certainly this is how people have dealt with this issue in the past, and it
works fine when PROJ.4 is just used for projections.

> My probem is that I view the projections and their math as pristene entities  and
> not disturbed with regtional egos and their arbitrary orientations of coordinate
> systems.
> I know my advice will be ignored but I could not resist expressing my displeasure
> with the inclusion of PM code within the proj.4 library.  PMS, if you will.

Well, the corruption started when I introduced support for converting
between different datums. At that point I was trying to make PROJ.4 into
a coordinate system conversion library rather than just a projections
library.  I can see why you feel that is a perversion of the original vision
of PROJ.4, and the focus of it's role, but that is the danger of open source.
Your work can be adopted an taken in directions you never intended.

That said, I think PROJ.4 is serving an important function for lots of other
projects by taking on the larger role of coordinate systems conversion and
that integrating that task in one library rather than two layered libraries
has some benefits.

Your advice isn't exactly disregarded ... your vision messages cause me lots of
angst!  It just that user demand (and my own needs) has led me to take PROJ.4
in a different direction than originally intended.  Obviously we all owe you
alot as you did all the hard work ... the stuff that I am far from competent
to do.  But in the end, I will still pursue the features I think are useful
and needed.

Best regards,
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

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