[Qgis-user] R: Importing a raster into a Geopackage
Kirk Schmidt
kirk at nortekresources.com
Wed Dec 2 09:44:32 PST 2020
Hi Nicolas:
I reached out to Alberto for the original data as the one on google
drive did not contain georeferencing and therefore would not write to a
geopackage. I tried to write the geopackafge from Alberto's data and I
generated 3 bands. I just got back from a meeting and I will play with
it some more.
Kirk
On 12/2/2020 12:10 PM, Nicolas Cadieux wrote:
> Hi Alberto,
>
> Can I share the file and your question in the gdal dev group? Perhaps
> they will have an answer to your problem. You can also do that
> yourself if you prefer.
>
> Kirt, if you have time, can you do the same run with the data in my
> google link? If you can’t duplicate the problem, then we will have a
> better idea if you share your QGIS version and OS. Perhaps there is
> change in the gdal version between both computers.
>
> Nicolas Cadieux
> https://gitlab.com/njacadieux <https://gitlab.com/njacadieux>
>
>> Le 2 déc. 2020 à 10:11, Alberto Vavassori
>> <alberto.vavassori at polimi.it> 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 <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
>>
>> <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 <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 <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
>>
>> Tel (902) 922.3607
>>
>> Email:kirk at nortekresources.com <mailto:kirk at nortekresources.com>
>>
>> Web:www.nortekresources.com <http://www.nortekresources.com>
>>
>>
>>
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>>
>> Nicolas Cadieux
>>
>> https://gitlab.com/njacadieux <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
>>
>> Tel (902) 922.3607
>>
>> Email:kirk at nortekresources.com <mailto:kirk at nortekresources.com>
>>
>> Web:www.nortekresources.com <http://www.nortekresources.com>
>>
>>
>>
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>> --
>>
>> Nicolas Cadieux
>>
>> https://gitlab.com/njacadieux <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 <mailto:kirk at nortekresources.com>
>> Web:www.nortekresources.com <http://www.nortekresources.com>
--
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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