[Qgis-user] R: Importing a raster into a Geopackage
Nicolas Cadieux
njacadieux.gitlab at gmail.com
Tue Dec 1 10:03:18 PST 2020
I tried
gdal_translate -of GPKG -co "BAND_COUNT=1"
C:/Users/Nicolas/Desktop/Land_cover_Corine2018.tif
C:/Users/Nicolas/Desktop/TEST.gpkg for the creation and
C:\>gdal_translate -of GPKG -co "TILE_FORMAT = TIFF"
C:/Users/Nicolas/Desktop/Land_cover_Corine2018.tif
C:/Users/Nicolas/Desktop/TEST.gpkg
Same problem. I wonder if we need to change the reading options...
https://gdal.org/drivers/raster/gpkg.html
"Opening options
By default, the driver will expose a GeoPackage dataset as a four band
(Red,Green, Blue,Alpha) dataset, which gives the maximum compatibility
with the various encodings of tiles that can be stored. It is possible
to specify an explicit number of bands with the BAND_COUNT opening option."
The problem could be when QGIS Reads the file, not when it writes the
file. I explains why we see 4 bands but not why values are changing. I
would make a bug report or ask the question on the gdal dev group to get
Even Rouault's attention.
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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