[Gdal-dev] support for ERDAS pyramid layers

[Frank Warmerdam]

kenboss wrote:
> I'm wondering whether support is eventually planned for ERDAS Imagine pyramid 
> layers (.rrd files).  
> 
> The Supported Formats documentation states that "The current implementation 
> ignores pyramid levels", implying that perhaps future implementations will 
> support them?  
> 
> Later in the same document I find the line "Erdas Imagine supports external 
> creation of overviews (with gdaladdo for instance)."  Does this mean to say that 
> I can actually cause Imagine to read GDAL's .ovr files by some means?

Ken,

It would appear that the documentation is out of date.

The existing Imagine driver will try to read rrd layers associated with an
imagine file if it can.  If not, it will check for the normal GDAL .ovr
file and use that if available.

However, gdaladdo, the overview builder will only build external overviews
for imagine files at this time, not internal ones.  For use in mapserver
that should be fine, but it means that imagine uses won't get any benefit
of GDAL overviews.  There are no plans to support producing .rrd files
at this time, but if someone wanted it bad enough to fund it, I would
be happy to add it.

I have updated the frmt_hfa.html file a bit.



Best regards,

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