[Qgis-user] Cell Statistics in QGIS

[Victor Olaya]

Using the Processing raster calculator to sum up layers should
correctly handle no-data values, and leave a no-data value in those
cells for which one of such values appears in the sum.

2014-04-14 11:29 GMT+02:00 Micha Silver <micha at arava.co.il>:
>
> On 14/04/2014 06:19, Leo Kris Palao wrote:
>
> Hi ALL QGIS users,
>
> Good day!
>
> I want to calculate the sum of the raster layers, but I want to ignore the
> no data values in the calculation. This is similar to cell statistics
> (spatial analyst) enable the Ignore NoData in calculations (optional) in
> ArcGIS.
>
>
> You can choose the GRASS module "r.series". Regarding no data cells, they
> are handled as follows (from the manual page):
>
> Without -n flag, the complete list of inputs for each cell (including NULLs)
> is passed to the aggregate function. Individual aggregates can handle data
> as they choose. Mostly, they just compute the aggregate over the non-NULL
> values, producing a NULL result only if all inputs are NULL.
>
> So if you use "method=sum" you'll get an output raster which sums all non
> null input cells.
>
>
>
> So far I am doing all my process in QGIS (batch processing is great in the
> processing toolbox). This is the only step that I am using ArcGIS because I
> cannot find the right tool in QGIS.
>
> Thanks in advance for any help.
>
> -Leo
>
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