Le 2 déc. 2020 à 10:11, Alberto Vavassori
<[email protected]> a écrit :
Hi Kirk,
I tried with another raster file that represents a temperature
distribution (continuous values). In this case, when I import it into
the Geopackage, I see the same issue that you have just described:
minimum and maximum values in the legend change, but it seems that
the actual values remain unchanged, thus correct. Unfortunately this
is not the case of the land cover raster (discrete set of values)
that I have shared with you: in this case, the raster characteristics
change, as we have all noticed.
Just another question, hoping that you might have an answer: is it
possible to store the symbology of a raster file inside the
Geopackage? I know that it is possible for vector data, by clicking
on “Style > Save style” in the “Symbology” tab. But I cannot find a
way to save the symbology in case of raster files.
Thanks a lot.
Alberto
*Da:* Qgis-user <[email protected]> *Per conto di
*Kirk Schmidt
*Inviato:* mercoledì 2 dicembre 2020 16:00
*A:* Nicolas Cadieux <[email protected]>;
[email protected]
*Oggetto:* Re: [Qgis-user] R: Importing a raster into a Geopackage
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
<image001.png>
<image002.png>
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
<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
<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 <[email protected]
<mailto:[email protected]>> 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
<[email protected]>
<mailto:[email protected]>
*Inviato:* martedì 1 dicembre 2020 17:40
*A:* Alberto Vavassori
<[email protected]>
<mailto:[email protected]>
*Cc:* [email protected]
<mailto:[email protected]>
*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
<[email protected]>
<mailto:[email protected]>
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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RR # 1
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B0K 1W0
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Nortek Resource Solutions Inc.
RR # 1
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B0K 1W0
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