On Wed, Sep 7, 2022 at 11:43 AM Michael Dufty via Qgis-user
wrote:
>
> It appears that there are two different native raster calculator tools in QGIS
>
> One is found in at the top of the raster menu
>
> The other is in the processing toolbox in the raster analysis group
>
Yeah, we know it's a mess.
Both are based on the same QGIS core implementations, they just use a
different GUI but they must give the same results.
>
>
> (Not to mention the GDAL raster calculator and SAGA raster calculator)
>
This one is based on GDAL instead and it may give different results.
>
>
> Can anyone explain the reason for there being two, and what the differences
> are?
>
> I’ve been very confused by it, mainly because the one in the raster menu does
> not appear to handle negative values correctly. I’d been wondering why NDVI
> type expressions with negatives randomly worked or not, and discovered it
> just depended on which raster calculator I used.
>
> Is it expected that the one in the raster menu doesn’t handle negative values
> correctly? It looks like it might do calculations based on unsigned integers
> regardless of the input and output raster formats.
>
You could file a bug report attaching a small dataset to reproduce the
issue and if you are using OpenCL acceleration (see global QGIS
settings).
Kind regards.
--
Alessandro Pasotti
QCooperative: www.qcooperative.net
ItOpen: www.itopen.it
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