Detrending DEM (QGIS)

Question

I’m trying to detrend a DEM in QGIS. 
The best guidance that I could find on the internet was this question : Removing elevation trend over sloped surfaces?

I couldn’t understand that so I would like to know if someone could explain how to remove the tilt of a DEM. 
I know that the best approach is to fit a plane and then subtract this from the original DEM. But I can’t understand the criteria to create this plane and how I perform the subtraction.
I can use python if needed.

Kazuhito · Answer

In QGIS:

Select several control points on your DEM to create the surface. Create a new point layer and digitize these points.
Obtain elevation data from the DEM at control points, by Add raster values to points tool in Processing Toolbox | SAGA | Vector <> raster
Start Polynomial regression tool in Processing Toolbox | SAGA | Geostatistics. Select your control points as the input, and choose [0] simple planer surface. Also make sure to set the extent and the cell size as same as your DEM.
Use raster calculator to subtract the output from the step 3 from your DEM. (or you may prefer Raster difference tool in Processing Toolbox | SAGA | Raster calculus).

Detrending DEM (QGIS)

One Answer

Add your own answers!

Ask a Question