[Qgis-developer] Processing with raster files > 4GB
G. Allegri
giohappy at gmail.com
Wed Nov 19 02:53:16 PST 2014
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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