I'm trying to use the graphical modeller to automate a certain process (extracting North-South facing slopes from a DEM).
The process is as follows:
- Calculate Slope
- Calculate Aspect
- Extract North-South Slopes using the raster calculator expression:
This works flawlessly when I do it step by step, using the default Processing toolbox raster calculator, Slope and Aspect.
When I try to input this in the Graphical modeller however I get an error: "pointer cannot be cast to type 'float'"
The aspect and slope are calculated as expected, but the raster calculator fails.
I've tried this in QGIS 3.8 and 3.10.
I've tried assigning the CRS to the slope and aspect layers before the calculation, and tried using the GDAL calculator (which returns a "TypeError").
My question is: What am I doing wrong here? The same steps work perfectly outside the graphical modeller, so I don't see why they should fail here.