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

[Andreas Neumann]

Hi Carlos,

GDAL would be my first choice - because it easy to automate. However, I 
don't know how can do my task with GDAL.

 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 - but this 
reclassifies all pixels, not only selected ones.

Maybe I could use http://www.gdal.org/gdal_calc.html with a conditional 
syntax?

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 [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 [1]
>  _______________________________________________
>  Qgis-developer mailing list
>  Qgis-developer at lists.osgeo.org
>  http://lists.osgeo.org/mailman/listinfo/qgis-developer [1]
> 
> 
> 
> Links:
> ------
> [1] http://lists.osgeo.org/mailman/listinfo/qgis-developer
> [2] http://www.psig.es