[Qgis-user] R: Importing a raster into a Geopackage

[Nicolas Cadieux]

Hi Sebastian and others,

I think the github has it wrong here  According to the documentation, 
the band count option is for _reading_ the file and not creating the 
file.  What I don't get is the fact that the data is being changed 
significantly (but not as much as when the "rendered image" option is 
selected (as expected) so that's not the problem here).   I tried 
QUALITY = 100 for writing to see if some compression was going on but 
it's the same problem.  Looks like some scaling issues.  The 1 to 4 band 
is not a problem (as this is the standard read option) but the value 
changes are.

gdal_translate -of GPKG -co "QUALITY = 100" 
C:/Users/Nicolas/Desktop/Land_cover_Corine2018.tif 
C:/Users/Nicolas/Desktop/TEST.gpkg

Nicolas

On 2020-12-01 12:17 p.m., Sebastian Gutwein wrote:
> This looks like the same issue you are having. 
> github.com/qgis/QGIS/issues/38227 
> <http://github.com/qgis/QGIS/issues/38227>
> According to the documentation linked in the issue you need to set the 
> band count to 1 otherwise it defaults to 4.
> gdal.org/drivers/raster/gpkg.html 
> <http://gdal.org/drivers/raster/gpkg.html>
> I have not tried this to see if it works.
>
> On Tue, Dec 1, 2020 at 11:52 AM Nicolas Cadieux 
> <njacadieux.gitlab at gmail.com <mailto:njacadieux.gitlab at gmail.com>> wrote:
>
>     Hi,
>
>     Looking at it now.  I see what you see.  I will try a few things.
>
>     Nicolas
>
>     On 2020-12-01 11:42 a.m., Alberto Vavassori wrote:
>>
>>     Hi Nicolas,
>>
>>     thank you for the answer. I send the raster that I am interested in.
>>
>>     Alberto
>>
>>     *Da:*Nicolas Cadieux <njacadieux.gitlab at gmail.com>
>>     <mailto:njacadieux.gitlab at gmail.com>
>>     *Inviato:* martedì 1 dicembre 2020 17:40
>>     *A:* Alberto Vavassori <alberto.vavassori at polimi.it>
>>     <mailto:alberto.vavassori at polimi.it>
>>     *Cc:* qgis-user at lists.osgeo.org <mailto:qgis-user at lists.osgeo.org>
>>     *Oggetto:* Re: [Qgis-user] Importing a raster into a Geopackage
>>
>>     Hi,
>>
>>     Send a sample data set if you can't figure it out.
>>
>>     Nicolas
>>
>>     On 2020-12-01 10:35 a.m., Nicolas Cadieux wrote:
>>
>>         Hi,
>>
>>         Perhaps this can help:
>>         https://gdal.orgdrivers/raster/gpkg.html
>>         <https://gdal.orgdrivers/raster/gpkg.html>
>>
>>         “Various kind of input datasets can be converted to
>>         GeoPackage raster :
>>
>>         ·Single band grey level
>>
>>         ·Single band with R,G,B or R,G,B,A color table
>>
>>         ·Two bands: first band with grey level, second band with
>>         alpha channel
>>
>>         ·Three bands: Red, Green, Blue
>>
>>         ·Four band: Red, Green, Blue, Alpha
>>
>>         GeoPackage rasters only support Byte data type.”
>>
>>         My guess is that if the original raster does not correspond
>>         to one of the categories above, it will be converted to the
>>         closest format.
>>
>>         Nicolas Cadieux
>>
>>         https://gitlab.com/njacadieux <https://gitlab.com/njacadieux>
>>
>>
>>
>>             Le 1 déc. 2020 à 09:58, Alberto Vavassori
>>             <alberto.vavassori at polimi.it>
>>             <mailto:alberto.vavassori at polimi.it> a écrit :
>>
>>             
>>
>>             Hello everybody. I have an issue regarding the Geopackage
>>             format. I have tried to import a singleband raster file
>>             (it represents the land cover, thus every pixel has a
>>             single integer value corresponding to the land cover
>>             class), but this operation seems to modify the raster
>>             characteristics: the raster becomes a 4-bands raster and
>>             the pixels values change accordingly (basically, the
>>             original raster is saved in the Geopackage as an RGB
>>             image). It seems to be a bug of QGIS. I have also tried
>>             to use GDAL translate through the processing toolbox of
>>             QGIS to convert the TIFF file to a Geopackage file, but
>>             the result is the same.
>>
>>             Has anybody faced this problem? May anybody suggest a way
>>             to work this problem out?
>>
>>             Thank you.
>>
>>             Alberto
>>
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>>     -- 
>>     Nicolas Cadieux
>>     https://gitlab.com/njacadieux  <https://gitlab.com/njacadieux>
>
>     -- 
>     Nicolas Cadieux
>     https://gitlab.com/njacadieux  <https://gitlab.com/njacadieux>
>
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-- 
Nicolas Cadieux
https://gitlab.com/njacadieux

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