On 01/09/2011 14:23, Even Rouault wrote:
As I did not use DATUM and PROJ creation option GDAL don't add it!
Yes, the mapping between WKT representation and ECW DATUM/PROJ is not perfect,
especially in the WKT -> DATUM/PROJ direction (the other direction is simpler).
You could perhaps try the updated ecw_cs.wkt file attached to ticket
http://trac.osgeo.org/gdal/ticket/4127
Finally I saw that gdal create only an aux.xml file to store his own proj
information and don't use the projection information from the header file. If
I
create this aux.xml file for all of my raster data it could work.
Yes, .aux.xml is a solution that works for most GDAL drivers. But of course, it
will only work in the GDAL-based software world.
I made the experience that ECW files do not work too well with the
*.aux.xml file and less common projections. Often gdalinfo cannot
convert the projected coordinates into lat/lon in it's output. And
especially in combination with Mapserver reprojection does often not
work correctly with ECW files that should read the projection info from
the *.aux.xml file.
But as soon as you apply the ECW specific DATUM and PROJ definitions and
add the corresponding projections/datums to the ecw_cs.wkt file (if
missing there) everything works like a charm. Also desktop clients like
ArcGIS 10 and QGIS work well with those ECW's if you add the missing
projections and datums to their own copy of the ecw_cs.wkt file.
Armin
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