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?
Mike, 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 : https://github.com/OSGeo/gdal/blob/trunk/gdal/apps/gdaladdo.cpp#L240), 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 accessible. Then you should be able to call BuildOverviews() on the file opened in GA_ReadOnly mode to build external overviews. Even -- Spatialys - Geospatial professional services http://www.spatialys.com _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
