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

Wed Dec 2 11:01:44 PST 2020

Alberto,
I found that by clicking on “Style > Save as Default” in the “Symbology”
tab it will store the symbology in the geopackage.

On Wed, Dec 2, 2020 at 10:11 AM Alberto Vavassori <
alberto.vavassori at polimi.it> wrote:

> 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 <qgis-user-bounces at lists.osgeo.org> * Per conto di *Kirk
> Schmidt
> *Inviato:* mercoledì 2 dicembre 2020 16:00
> *A:* Nicolas Cadieux <njacadieux.gitlab at gmail.com>;
> qgis-user at lists.osgeo.org
> *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
>
>
>
> 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
>
> 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
>
> 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> 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>
> <njacadieux.gitlab at gmail.com>
> *Inviato:* martedì 1 dicembre 2020 17:40
> *A:* Alberto Vavassori <alberto.vavassori at polimi.it>
> <alberto.vavassori at polimi.it>
> *Cc:* 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
>
>
>
> “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
>
>
>
> Le 1 déc. 2020 à 09:58, Alberto Vavassori <alberto.vavassori at polimi.it>
> <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
>
> --
>
> Nicolas Cadieux
>
> https://gitlab.com/njacadieux
>
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> --
>
> Nicolas Cadieux
>
> https://gitlab.com/njacadieux
>
>
>
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> --
>
> Kirk Schmidt, MScF, BScF, RPF
>
> General Manager
>
> Nortek Resource Solutions Inc.
>
> RR # 1
>
> Thorburn, NS
>
> B0K 1W0
>
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> --
>
> Nicolas Cadieux
>
> https://gitlab.com/njacadieux
>
>
>
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>
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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: kirk at nortekresources.com
>
> Web: www.nortekresources.com
>
>
>
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>
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> --
>
> Nicolas Cadieux
>
> https://gitlab.com/njacadieux
>
> --
>
> Kirk Schmidt, MScF, BScF, RPF
>
> General Manager
>
> Nortek Resource Solutions Inc.
>
> RR # 1
>
> Thorburn, NS
>
> B0K 1W0
>
> Tel (902) 922.3607
>
> Email: kirk at nortekresources.com
>
> Web: www.nortekresources.com
>
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