[gdal-dev] Re: Units to Feet in ECW Metadata

[Jukka Rahkonen]

Mullins, Steven <Steven.Mullins <at> dmme.virginia.gov> writes:

> 
> Hello all.  I've ran into a bit of trouble doing a geotiff to ECW conversion.  
...
...
> 
> Now the units are in Meters and the ESPG code for my projection EPSG:32047 has
been dropped.  Another twist is
> that ACAD correctly projects the resulting ECW, while ARCGIS does not.  Seems
that ACAD ignores the UNITS
> tag while ARCGIS does not.  
> 
> Does anyone know how to make ECW keep the correct projection unit?

Hi,

All I know is that you can correct your image afterwards by using free ECW Image
Header Editor that can be downloaded from http://ermapper.com/ProductView.aspx?t=189

Gdal document at http://www.gdal.org/frmt_ecw.html tells:
When writing coordinate system information to ECW files, many less common
coordinate systems are not mapped properly. If you know the ERMapper name for
the coordinate system you can force it to be set at creation time with the PROJ
and DATUM creation options.

So it may be difficult to get a proper ECW projection directly from gdal, but
knowing the exact names that ER Mapper is using for your projection and datum
might help in it. Unfortunately ECW Header Editor does not have a list of ECW
projections. Projection names can be found from ER Mapper Professional user
manual that can be downloaded from http://ermapper.com/Documents.aspx?t=213&dc=17

-Jukka Rahkonen-