Hi Andreas, Yes, you can use gdal_calc.py Certainly you need to perform several processes, but are very fast!
Be careful with bands! Perhaps you will want to separate them. Ciao, * <http://www.psig.es>* *Carlos López Quintanilla* www.psig.es [email protected] +34 699.680.261 2014-11-19 9:26 GMT+01:00 Andreas Neumann <[email protected]>: > 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] >> >> [email protected] >> +34 699.680.261 >> >> 2014-11-19 9:05 GMT+01:00 Andreas Neumann <[email protected]>: >> >> 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 >>> [email protected] >>> http://lists.osgeo.org/mailman/listinfo/qgis-developer [1] >>> >> _______________________________________________ >> Qgis-developer mailing list >> [email protected] >> http://lists.osgeo.org/mailman/listinfo/qgis-developer [1] >> >> >> >> Links: >> ------ >> [1] http://lists.osgeo.org/mailman/listinfo/qgis-developer >> [2] http://www.psig.es >> >
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