[Qgis-user] Raster calculator question

[Carlos Cerdán]

Hi Andreas:

Yes, it always evaluates to true because of "OR" condition , so try:

(lake_mask > 0) * lake_mask + (lake_mask<=0)*dtm

Good luck

Carlos




2014-04-24 1:53 GMT-05:00 Andreas Neumann <a.neumann at carto.net>:

> Hi,
>
> I have a hard time understanding the raster calculator syntax.
>
> I would like to merge two rasters: DTM and lake mask. Let's call the one
> dtm and the other lake_mask.
>
> When the lake_mask has a value > 0 then I would like to take the value
> of the lake_mask, otherwise the value of the dtm.
>
> What would an appropriate syntax look like?
>
> I tried something along
>
> ((lake_mask > 0) * lake_mask) OR dtm
>
> But all I get in the resulting grid are values of 1. I guess it is
> because it always evaluates to true?
>
> Thanks for your help.
>
> Andreas
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