Hi all:
I ran the r.stats to get a list of each pixel value on my test data (A
small DEM) before and after conversion to a geopackage (see second image
below). The values and summary stats are identical for the two rasters
but the default legend entry has a different min and maximum value. So,
I can conclude that the data is being written correctly but the default
display parameters for the geopackage are different than a geotiff.
Kirk
On 12/1/2020 3:24 PM, Nicolas Cadieux wrote:
Hi,
I changed the link so you have access to more files.
https://drive.google.com/drive/folders/1fMl9odowUFFRQFK61rTxgHeom_D8ymN6?usp=sharing
Nicolas
On 2020-12-01 1:58 p.m., Kirk Schmidt wrote:
Hi Nicolas
I did the same and the legend indicates a change magnitude but if I
subtract the geopackage raster from the original, all pixels equal zero.
Kirk
On 12/1/2020 2:36 PM, Nicolas Cadieux wrote:
Hi,
Tried this:
gdal_translate -of GPKG -b 1
C:/Users/Nicolas/Desktop/Land_cover_Corine2018.tif
C:/Users/Nicolas/Desktop/test.gpkg
I read 4 band and still get data modifications.
Nicolas
On 2020-12-01 1:28 p.m., Kirk Schmidt wrote:
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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Nortek Resource Solutions Inc.
RR # 1
Thorburn, NS
B0K 1W0
Tel (902) 922.3607
Email:k...@nortekresources.com
Web:www.nortekresources.com
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Kirk Schmidt, MScF, BScF, RPF
General Manager
Nortek Resource Solutions Inc.
RR # 1
Thorburn, NS
B0K 1W0
Tel (902) 922.3607
Email: k...@nortekresources.com
Web: www.nortekresources.com
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