[gdal-dev] TIFF overviews issue

[Fabian Schindler]

Perfect, your workaround works for me.
As I'm mostly dealing with small fairly small images, the performance 
decrease may not be a concern for me. I'll stick with this solution 
until I can definitely say that the target system has libtiff 4.0.

Thanks Even!


On 12/01/2012 11:37 AM, Even Rouault wrote:
>> I can also reproduce with libtiff 3.9.2. libtiff 3.X suffers sometimes from
>> some problems when generating overviews in a interleaved way, as it is
>> done by BuildOverviews("NEAREST", [2,4,8,16]). Those problems have been
>> corrected in libtiff 4.0
>>
>> A way to workaround this is to generate each overview level one after
>> another one, like this :
>>
>> out_ds.BuildOverviews("NEAREST", [ 2 ])
>> out_ds.BuildOverviews("NEAREST", [ 4 ])
>> out_ds.BuildOverviews("NEAREST", [ 8 ])
>> out_ds.BuildOverviews("NEAREST", [ 16 ])
>>
>> This will work on both libtiff 3.X and libtiff 4.0. Note that it might
>> perform a little less than generating all the levels in a single
>> instruction, since the source data must be read several times.
> In the libtiff 3.X case, I've just implemented in GDAL trunk the workaround in
> the GTiff driver
> _______________________________________________
> gdal-dev mailing list
> gdal-dev at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/gdal-dev