[Gdal-dev] Adding Projection to ECW files ?

[Frank Warmerdam]

On 6/20/05, Bill Binko <bill at binko.net> wrote:
> I knew you were busy with the conference: this is important to me, but not
> critical.  Unfortunately, I got the ECWs rather than the TIFFs, so I can't
> re-compress them.  I considered using gdal_translate from ECW to ECW, but
> was worried that I might lose fidelity.

Bill, 

Indeed,  recompressing would be somewhat lossy.

> > Assuming you don't want to regenerate the ECWs you should be able to push
> > the georeferencing into the PAM file (.aux.xml) with a small python script.
> >
> 
> Is that PAM file documented anywhere?  I can write a script to edit XML if
> I know what I'm writing to.

It is essentially a subset of the VRT format, so the VRT docs might help.   To 
set the SRS, just edit it add an <SRS>+proj=utm +zone=17 +datum=WGS84</SRS>
node as a child of the <PAMDataset>. 

A minimal file might look like:

abc.ecw.aux.xml:
<PAMDataset>
  <SRS>+proj=utm +zone=17 +datum=WGS84</SRS>
</PAMDataset>

Any followup likely ought to stay on the gdal-dev list. 

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