[QGIS-Developer] 2 questions on saving rasters in 3.4

Nyall Dawson nyall.dawson at gmail.com
Thu Jan 24 02:09:08 PST 2019

On Thu, 24 Jan 2019 at 17:59, Andreas Neumann <a.neumann at carto.net> wrote:
> Hi,
> I have two questions about saving rasters in QGIS 3.4:
> 1.
> If I use "Right-klick layer" --> "Export" --> "Save AS" then I can't choose the ESRI ASCII Grid format described in "Settings" --> "Options" --> "GDAL" as "AAIGrid".
> Any idea why this format is not available for exporting rasters?

The raster file writer only currently supports formats for which GDAL
has "creation" support, not "copy" . See
https://www.gdal.org/formats_list.html - AAIGrid supports copies only.

This should be fixable with moderate effort -- we could create a
temporary dataset in a supported format (possibly even in memory for
smaller rasters), and then use GDAL's createcopy to write the result.
This would open up support for all raster drivers with copy but not
create support, including AAigrid, and a whole lot of other useful
formats too.

> 2.
> As an alternative I can use the "Raster" --> "Extraction" --> "Clip raster by extent". This works fine, but I can't set the number of decimal places after the comma.
> E.g. if I export a terrain model I would like to use 2-3 places after the decimal, not the full 8 digits, which is a false accuracy.

I don't fully understand the issue here -- although the dialog is
showing that many decimal places, it doesn't affect the output file if
the extraneous digits are set to 0.


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