[OSRS-PROJ] PROJ 4.4.3 - about epsg...

Frank Warmerdam warmerdam at pobox.com
Fri Apr 20 14:44:43 EDT 2001

Bart Adriaanse wrote:
> Thanks for the 4.4.3 update Frank !
> I have not compiled it yet but already have a question about the epsg file
> you created so couragously...
> I do understand the conversion was far from trivial and surely you can not
> be 100% sure about the accuracy of all of the parameters in there.
> I checked the epsg file and for the Netherlands coordinate system i find
> that the datum shift is missing there.
> Now how can we contribut to the quality of the epsg parameters if a user
> like me finds one that can be improved ?
> Should we manually update it in the file or should we file a bug report so
> you can improve the batch procedure used to generate the file ?
> I can easily fix it here in my own copy but i wonder how i can share the fix
> with other proj users.
> Otherwise the update looks very promising, i'll be compiling it to a DLL and
> testing the 7 paramer shift for amersfoort in a few weeks...


I believe the current logic in my code for generating the EPSG mapping is
to only generate a datum definition for coordinates systems where EPSG offers
one, and only one route from that datum directly to WGS84.  This means that
alot of interesting datums end up not being if for instance multiple 
approximations exist.  

For now I would encourage you to file a bug report in Bugzilla, and I will
try to come up with a mechanism to automatically patch selected coordinate
systems based on an override file when doing the automated EPSG to PROJ.4

It must be stressed that the epsg definition file isn't well tested, and
I would encourage anyone running into problems with it to report them.  

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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