[Qgis-developer] Processing with raster files > 4GB

[G. Allegri]

And do you have problems with GRASS (directly, not through Processing)?
In GRASS7 you can even drectly write to Geotiff without passing through the
internal format (http://grass.osgeo.org/grass70/manuals/r.external.out.html
).
If GDAL is built with bigtiff support there souldn't be problems...

giovanni

2014-11-19 10:44 GMT+01:00 Andreas Neumann <a.neumann at carto.net>:

> Hi Giovanni,
>
> I need to change all pixels that have the value of 249 to a value of 255.
> All other pixels should stay at their value.
>
> Andreas
>
> Am 2014-11-19 10:21, schrieb G. Allegri:
>
>> From my grayscale tiff images I want to replace one pixel value
>>>
>> (249) with white (255). All other pixels should stay at the value they
>> have.
>>  >
>>  > I came across https://github.com/chiatt/gdal_reclassify [1] - but
>> this reclassifies all pixels, not only selected ones.
>>  >
>>  > Maybe I could use http://www.gdal.org/gdal_calc.html [2] with a
>> conditional syntax?
>>
>> Hi Andreas, do you need to change the value of one specific pixel
>> only? I mean the pixel at [x,y] index?
>>
>> giovanni
>>
>>
>>>   > Thanks,
>>  > Andreas
>>  >
>>  > Am 2014-11-19 09:10, schrieb Carlos López PSIG:
>>  >>
>>  >> Hi Andreas,
>>  >>
>>  >> I also had problems to reclassify BIGTIFF with SAGA and GRASS!
>>  >> Finally I used GDAL!
>>  >>
>>  >> Best regards,
>>  >>
>>  >>  [2]
>>  >>
>>  >> CARLOS LÓPEZ QUINTANILLA
>>  >>
>>  >> www.psig.es [3] [2]
>>
>>  >>
>>  >> carlos.lopez at psig.es
>>  >> +34 699.680.261
>>  >>
>>  >> 2014-11-19 9:05 GMT+01:00 Andreas Neumann <a.neumann at carto.net>:
>>  >>
>>  >>> Hi,
>>  >>>
>>  >>> I tried various tools, e.g.
>>  >>>
>>  >>> * SAGA reclassify
>>  >>> * GRASS r.mapcalc
>>  >>>
>>  >>> Both work fine on smaller data sets, but fail on big data sets.
>>  >>>
>>  >>> This is on Win7 64bit, with the OSGeo4W installer. I have 8gb RAM
>>  >>> and 40GB disk free on C:, more free space on other disks where
>> the
>>  >>> data resides.
>>  >>>
>>  >>> I am not totally sure if it is the Bigtiff issue or some other
>>  >>> issue. It is just a guess that maybe I am hitting a limit with
>> tiff.
>>  >>> It is not fully transparent to me what Processing is doing in the
>>  >>> background (what file formats with what options it creates).
>>  >>>
>>  >>> It may also be an issue with SAGA or GRASS directly.
>>  >>>
>>  >>> Thanks if you know anything,
>>  >>> Andreas
>>  >>>
>>  >>> Am 2014-11-18 21:15, schrieb Giovanni Manghi:
>>  >>>
>>  >>> Hi,
>>  >>>
>>  >>> I am having a lot of troubles with large raster files and
>>  >>> processing.
>>  >>>
>>  >>> The intermediate results can go >4GB. Processing stops with not
>> so
>>  >>> helpful error messages.
>>  >>>
>>  >>> I wonder if processing is hitting the 4GB limit. Can I force
>>  >>> processing
>>  >>> to use the BIGTIFF option or a raster format that can handle >4GB
>>  >>> files?
>>  >>>
>>  >>> Hi Andreas, what tool specifically?
>>  >>>
>>  >>> cheers
>>  >>>
>>  >>> -- Giovanni --
>>  >>> _______________________________________________
>>  >>> Qgis-developer mailing list
>>  >>> Qgis-developer at lists.osgeo.org
>>  >>> http://lists.osgeo.org/mailman/listinfo/qgis-developer [4] [1]
>>  >>
>>  >>  _______________________________________________
>>  >>  Qgis-developer mailing list
>>  >>  Qgis-developer at lists.osgeo.org
>>  >>  http://lists.osgeo.org/mailman/listinfo/qgis-developer [4] [1]
>>  >>
>>  >>
>>  >>
>>  >> Links:
>>  >> ------
>>  >> [1] http://lists.osgeo.org/mailman/listinfo/qgis-developer [4]
>>  >> [2] http://www.psig.es [3]
>>  >
>>  > _______________________________________________
>>  > Qgis-developer mailing list
>>  > Qgis-developer at lists.osgeo.org
>>  > http://lists.osgeo.org/mailman/listinfo/qgis-developer [4]
>>
>> Links:
>> ------
>> [1] https://github.com/chiatt/gdal_reclassify
>> [2] http://www.gdal.org/gdal_calc.html
>> [3] http://www.psig.es
>> [4] http://lists.osgeo.org/mailman/listinfo/qgis-developer
>>
>


-- 
Giovanni Allegri
http://about.me/giovanniallegri
Twitter: https://twitter.com/_giohappy_
blog: http://blog.spaziogis.it
GEO+ geomatica in Italia http://bit.ly/GEOplus
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