Hi Nicolas:
try the -b 1 parameter. I just tried this and wrote a single band
raster from a 3 channel tiff.
Kirk
On 12/1/2020 2:03 PM, Nicolas Cadieux wrote:
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.git...@gmail.com <mailto:njacadieux.git...@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.git...@gmail.com>
<mailto:njacadieux.git...@gmail.com>
*Inviato:* martedì 1 dicembre 2020 17:40
*A:* Alberto Vavassori <alberto.vavass...@polimi.it>
<mailto:alberto.vavass...@polimi.it>
*Cc:* qgis-user@lists.osgeo.org <mailto:qgis-user@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.vavass...@polimi.it>
<mailto:alberto.vavass...@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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