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

[Andreas Neumann]

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]
>  >>
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>  >>
>  >>
>  >> Links:
>  >> ------
>  >> [1] http://lists.osgeo.org/mailman/listinfo/qgis-developer [4]
>  >> [2] http://www.psig.es [3]
>  >
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> 
> 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