[Gdal-dev] EPSG 6.5 and extended Dictionary lookups

[Ed McNierney]

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

Ed McNierney
President and Chief Mapmaker
TopoZone.com / Maps a la carte, Inc.
73 Princeton Street, Suite 305
North Chelmsford, MA  01863
ed at topozone.com
(978) 251-4242  

-----Original Message-----
From: Frank Warmerdam [mailto:warmerdam at pobox.com] 
Sent: Friday, March 05, 2004 1:24 PM
To: gdal-dev
Subject: [Gdal-dev] EPSG 6.5 and extended Dictionary lookups

Folks,

As part of the GDAL 1.2.0 release I updated to EPSG 6.5 coordinate
systems.
That should be in the beta snapshot.

I have also (in CVS) added support for reading coordinate system
dicionaries.
This mechanism basically allows coordinate system codes to be looked up
in a text file (from the GDAL data directory), where the code is
corresponded to a WKT representation of the coordinate system.

I am currently using these dictionary files to hold a bunch of
"non-standard"
EPSG coordinate systems. Basically a bunch of special codes uses in the
WMS world (and harvested from a CubeWerx dictionary in a similar format)
and from all the non-EPSG ESRI coordinate systems normally found in
their "epsg"
directory.

The dictionary files are just simple text files, following the following
rules:
  o Empty lines, or lines starting with "#" are ignored (comments).
  o Lines starting with "include " can name an additional file that will
    be searched.
  o data lines should be a code seperated from the WKT representation by
a
    comma.

eg.

include cubewerx_extra.wkt
#
#  OGC-defined "AUTO" codes
#  http://www.digitalearth.gov/wmt/auto.html
#
42001,PROJCS["WGS 84 / Auto UTM%s",GEOGCS[...]] 42002,PROJCS["WGS 84 /
Auto Tr. Mercator",...]

A new method, OGRSpatialReference::importFromDict() has been added
supporting the dictionaries.  As well the SetFromUserInput() now
supports the funky format "DICT:filename,code" as a way of requesting an
arbitrary dictionary entry.
Also, the importFromEPSG() method will now search the epsg.wkt
dictionary (which includes the cubewerx and esri definitions) *if* the
coordinate system isn't found in the pcs.csv or gcs.csv files.

Other than providing a heads up, I am writing to see if there is anyone
interested in coordinate system use through GDAL that would like a crack
at testing this *before* the 1.2.0 release.  If so, please grab a
nightly snapshot and give it a spin.

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

_______________________________________________
Gdal-dev mailing list
Gdal-dev at remotesensing.org
http://remotesensing.org/mailman/listinfo/gdal-dev