[Gdal-dev] using gdaladdo with tiled tifs

[Jeff Hoffmann]

Frank Warmerdam wrote:
> Jeff Hoffmann wrote:
> 
>> Actually, I guess with fairly small tiles compressed overviews may not 
>> be such a bad thing since I won't be particularly CPU-constrained and 
>> they should decompress pretty quickly.  Maybe some benchmarking might 
>> be in order.  I think the thing that got me wondering this is that you 
>> don't really see much information about the overviews other than their 
>> size so I guess I just always assumed they replicated the settings of 
>> the original image.
> 
> 
> Jeff,
> 
> You can see details about them with the tiffinfo application if needed.
> It is part of libtiff, but can be found in FWTools.

Wow, if I would have known about that program I wouldn't have had to ask 
my question.  Turns out you were close on the overviews.  The block size 
is 128x128 not 256x256, but I wasn't able to change it using --config 
options to gdaladdo.  Also, the compression does seem to carry over to 
the overviews.  I wasn't able to create uncompressed overviews from 
compressed source (it crashed), nor was I able to add compressed 
overviews to an uncompressed source (even though the documentation seems 
to suggest you can).

-- 
Jeff Hoffmann
Head Plate Spinner
PropertyKey.com