[gdal-dev] Computing my overviews for GeoTIFF

[thomas bonfort]

Here's a working c version:
https://gist.github.com/tbonfort/1e8630cf4b9bc82471c164e422c1cce7

On Tue, Jul 13, 2021 at 2:55 PM thomas bonfort <thomas.bonfort at gmail.com> wrote:
>
> https://www.mail-archive.com/gdal-dev@lists.osgeo.org/msg36305.html
> :)
>
> On Tue, Jul 13, 2021 at 2:53 PM Javier Jimenez Shaw <j1 at jimenezshaw.com> wrote:
> >
> > Thanks Thomas and Even.
> >
> > Thomas, about using cogger (that would be great), I forgot to mention that I am doing it from a C++ library. Is there already a C/C++ API?
> >
> > Cheers,
> > Javier
> > .___ ._ ..._ .. . ._.  .___ .. __ . _. . __..  ... .... ._ .__
> > Entre dos pensamientos racionales
> > hay infinitos pensamientos irracionales.
> >
> >
> >
> > On Tue, 13 Jul 2021 at 14:15, thomas bonfort <thomas.bonfort at gmail.com> wrote:
> >>
> >> Javier,
> >> You can use https://github.com/airbusgeo/cogger#advanced to do that,
> >> provided that you have an internally tiled geotiff.
> >>
> >> --
> >> thomas
> >>
> >> On Tue, Jul 13, 2021 at 2:04 PM Even Rouault <even.rouault at spatialys.com> wrote:
> >> >
> >> > Javier,
> >> >
> >> > You can use the "NONE" resampling method in BuildOverviews() or gdaladdo to create the overviews IFD without allocating any storage, and then you can open the file in update mode to set whatever values you want. APPEND_SUBDATASET=YES will not set the appropriate value for the SubFileType TIFF tag, and thus such pages won't be recognized as overviews
> >> >
> >> > Even
> >> >
> >> > Le 13/07/2021 à 13:57, Javier Jimenez Shaw a écrit :
> >> >
> >> > Hi
> >> >
> >> > I am computing the overviews of a GeoTIFF on my own (using the GPU, much faster), and I want to include them in the tif file (also in the ovr sidecar file).
> >> > What is the best way to do it? Just creating a multipage TIFF (I guess with the option APPEND_SUBDATASET=YES)? Is there anything else needed (metadata, tiff tags, etc)?
> >> >
> >> > So far I want to do it in RGBA 8 bit images. (In the future I want to do it also in float32 images with nodata value and any number of bands, but no hurry).
> >> >
> >> > I am using GDAL 3.3.1
> >> >
> >> > Any help is welcome.
> >> >
> >> > Thanks.
> >> > Javier.
> >> > .___ ._ ..._ .. . ._.  .___ .. __ . _. . __..  ... .... ._ .__
> >> > Entre dos pensamientos racionales
> >> > hay infinitos pensamientos irracionales.
> >> >
> >> >
> >> > _______________________________________________
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> >> > gdal-dev at lists.osgeo.org
> >> > https://lists.osgeo.org/mailman/listinfo/gdal-dev
> >> >
> >> > --
> >> > http://www.spatialys.com
> >> > My software is free, but my time generally not.
> >> >
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