I have a raster with slope values and want to calculate a raster, which only shows values under and over a certain threshold for example 50. In the raster calculator I can do this manually by the expression
"Slope@1" >= 50
As I want to do this for several rasters and it is only one step in a chain, I would like to include it as a step in the graphical modeller of QGIS.This provides the GDAL Raster Calculator, the modeler only tool Calculator and the Saga Raster Calculator, but in none of these I can find out, what to type in to get the desired result.
Best Answer
If you choose "GDAL Raster calculator",
Input layer A
would beSlope
(though grayed out in modeller),Number of raster band
=1
, and theCalculation in gdalnumeric syntax using...
would beA*(A>=50)
.Of
A*(A>=50)
the latter part (A>=50) returns 1 (TRUE) or 0 (FALSE). So the resultant equation A times 1 or 0 (A*1, A*0) is equivalent to setting a threshold value.