[Gdal-dev] projection, geodesy and csv files

[Frank Warmerdam]

mathieu_gdal wrote:
> Dear all,
> 
> I use GDAL to display and geo-reference GeoTiff files.
> 
> I have noticed that the geo-referencement procedures I use fail if the 
> .csv files (ellipsoid.csv, gpc.csv, …) are not installed with the app.
> 
>  
> 
> -          Where could I get a definition of each .csv files?

Mathieu,

The files required by GDAL should be available from the gdal/data directory
in the CVS source tree.  Are you asking what each file is used for?  That
is somewhat complicated to answer.  In short most of them are derived from
specific tables in the EPSG database so reviewing information from the EPSG
site might be helpful.

   http://www.epsg.org/

> -          Are those .csv files specific to GDAL, or LiGeoTiff?

The .csv files were created by me based on a simple dump of EPSG .mdb
tables to .csv format primarily for the use of GDAL and libgeotiff.  Other
packages also use either my .csv files, or other dumps of the same tables,
in order to implement EPSG support.

> -          Where in the GDAL could could I find sample for accessing 
> those tables? cpl_csv.h is for parsing csv files, is there a layer on 
> top of this to access a list of projections and datums?

Specific places where they are used are:

   gdal/frmts/gtiff/libgeotiff/geo_normalize.c - GeoTIFF support
   gdal/ogr/ogr_fromepsg.cpp - Translate EPSG coordsys to WKT format.

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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