[gdal-dev] datum projection info in ecw

[Armin Burger]

Nicholas

I was interested about similar things a few weeks ago and got quick help 
in this forum. As jean-Claude already mentioned there's a header editor 
for Windows that allows you to see/edit the datum and projection info. 
Jean-Claude also created a tool "ecwhed" that allows you to get and set 
these parameters via the command line, at least under Linux it compiles 
easily, it requires the ECW SDK.

If you create ECW's via GDAL you should use the options -co "PROJ=..." 
and -co "DATUM=..." to be sure what GDAL writes to the ECW header. For 
reading ECW files GDAL uses the definitions in the file "ecw_cs.wkt" (on 
Unix under /usr/local/share/gdal/). There you can add your own 
projections and datums or modify existing ones, eg. adding datum shift 
parameters. Programs that use GDAL for raster rendering like QGIS or 
ArcGis 10 can also work with these new projection definitions if you add 
them to their own "ecw_cs.wkt" file, Mapserver takes the file of the 
GDAL installation.

Regards
Armin



On 28/06/2011 03:09, nicholas.g.lawrence at tmr.qld.gov.au wrote:
> Hello all,
>
> Does anyone know where the datum and projection information is stored
> inside an ecw?
>
> Kind regards,
>
> *
> Nicholas Lawrence*
> Senior Spatial Science Officer | Darling Downs Region / Toowoomba Office *
> Assets & Operations* Division | Department of Transport and Main Roads
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