[gdal-dev] Removing in-file overviews
even.rouault at spatialys.com
Thu Sep 8 11:02:33 PDT 2016
Le jeudi 08 septembre 2016 18:40:48, Michael Aschenbeck a écrit :
> Hello GDAL developers,
> For my application I need to create an *.ovr file, and it usually works
> using BuildOverviews.
> However, when I call BuildOverviews via C++ on a certain dataset, nothing
> happens because the overview is already included in the file. Is it
> possible to delete the in-file overview or move it to an *.ovr file using
> the C++ API?
Deleting overviews depends on the file format. Works for TIFF for example. You
can call BuildOverviews() with nOverviews == 0 and panOverviewList == NULL to
clear existing overviews (I realize this isn't yet documented in the API.
That's what gdaladdo -clean does :
assuming you've open the file in GA_Update mode.
Note that in the case of TIFF, this will not recover file space (you'll need to
do a gdal_translate to do that), but just make the previous content no longer
Then you should be able to call BuildOverviews() on the file opened in
GA_ReadOnly mode to build external overviews.
Spatialys - Geospatial professional services
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