[Qgis-user] batch-saving raster files from QGIS

[Radim Blazek]

On Tue, Apr 28, 2015 at 1:23 PM, Torsten Lange <torsten.lange at mail.de> wrote:
>
> Hello,
>
> I would like to batch-write some raster files from a project to one common
> folder using a script. This is my function:
>
> def writeRaster(rasterObj, pathToFile, cols, rows, rasterExtentObj,
> rasterCRSObj):
>     provider = myRaster.dataProvider()
>     pipe = QgsRasterPipe()
>     pipe.set(provider.clone())
>     file_writer = QgsRasterFileWriter(pathToFile)
>     file_writer.writeRaster(pipe, cols, rows, rasterExtentObj, rasterCRSObj)

If you set on the pipe only the provider, you get 'raw' data, you need
to clone the whole layer's pipe

pipe = QgsRasterPipe( rasterLayer.pipe() )

see https://github.com/qgis/QGIS/blob/final-2_8_0/src/app/qgisapp.cpp#L5077

Radim

> (Its a slightly modified example I found at nullege.com.)
>
> For normal rasters this works just fine, but not for maps (scanned and
> georeferenced). The map colors are recoded to grey-values, as one could
> expect. Is there a way to keep the colors? From what I have seen, there is
> no parameter to handle this in a QgsRasterPipe().
>
> Also, I remember once I tried to create a virtual raster cataloge using
> these maps. That failed because the maps used different color palettes. I
> guess they should be in RGB to create the vrt cataloge, shouldn't they?
>
> Thanks for suggestions, Torsten
>
>
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