[gdal-dev] Downsampling with gdal_translate and overviews

[jratike80]

Julien Michel-2 wrote
> Hi all,
> 
> ...
> So here are 
> my questions :
> 
> - Is gdal_translate using the nearest overview level as a start for 
> resampling ?
> 
> - Is there a way to prevent that (other than removing the ovr file) ?
> 
> - Is it expected than the resampling yields artifacts when ovr files are 
> present ?
> 
> Thanks a lot for your help,
> 
> Regards,
> 
> Julien
> 
> -- 
> Julien MICHEL
> CNES - DSO/SI/2A


Hi,

There are some answers to your question in the gdalwarp documentation
http://www.gdal.org/gdalwarp.html.

-ovr level|AUTO|AUTO-n|NONE>:
    (GDAL >= 2.0) To specify which overview level of source files must be
used. The default choice, AUTO, will select the overview level whose
resolution is the closest to the target resolution. Specify an integer value
(0-based, i.e. 0=1st overview level) to select a particular level. Specify
AUTO-n where n is an integer greater or equal to 1, to select an overview
level below the AUTO one. Or specify NONE to force the base resolution to be
used (can be useful if overviews have been generated with a low quality
resampling method, and the warping is done using a higher quality resampling
method). 

It is also possible that a solution/workaround for your problem could be to
use gdalwarp instead of gdal_translate.

-Jukka Rahkonen-



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