[Gdal-dev] EPSG 6.5 and extended Dictionary lookups

[Frank Warmerdam]

Ed McNierney wrote:
> Frank -
> 
> Thanks for this change; although it hasn't been a HUGE problem, I really
> don't like polluting my epsg files with various other coordinate
> systems.  This will certainly help in the maintenance department!

Ed,

I should clarify that this doesn't affect PROJ.4.  Proj.4 has similar concepts
of dictionary lookup (with the include concept) but what I am talking about
really is at the OGRSpatialReference object level in GDAL.  OGR has pretty
much its own coordinate system handling logic built around OGC Well Known
Text format.  It still uses PROJ.4 to do transformations, but just converts
the WKT format to PROJ.4 strings "at the last moment".

Part of the reasoning here is that PROJ.4 coordinate system definitions
strings aren't really as comprehensive as WKT (more so in the past ... some
of the missing information has been creeping into PROJ.4).

Now, the epsg and other lookup dictionaries for PROJ.4 are built by looking
up things on the OGRSpatialReference, so I hope my changes will make it
easier to build and maintain PROJ.4 dictionaries in the future.

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