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

[G. Allegri]

Nice to know that gdal_calc works fine ;)
I work a lot with gdal + numpy, even for custom tools, and I admit they
work very well together!


2014-11-19 11:41 GMT+01:00 Andreas Neumann <a.neumann at carto.net>:

>  Hi,
>
> I will have to do further testing about GRASS. On Windows (OSGeo4W
> install) it does not work too well. It probably works better on Linux.
>
> The gdal_calc.py solution works very fast though - glad that we came to
> this solution!
>
> Andreas
>
>
> On 19.11.2014 11:25, G. Allegri wrote:
>
> 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
>
>
>


-- 
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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