[Qgis-user] R: Importing a raster into a Geopackage
Nicolas Cadieux
njacadieux.gitlab at gmail.com
Tue Dec 1 10:36:33 PST 2020
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.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
>>
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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
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>
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--
Nicolas Cadieux
https://gitlab.com/njacadieux
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