Monday, June 24, 2024

Smoothing Contour Line/Polyline in QGIS and AutoCAD

 Often we work with datasets that needs to be represented by continuous lines/polylines such as contour lines. If there is no smoothing between a the line nodes (vertices), the visual appearance looks questionable. Let see how we can smooth lines/polylines in both QGIS and AutoCAD.


In QGIS, you need to set the 'Symbol Layer Type' >> 'Geometry Generator' to: smooth($geometry, 5).

This will smooth the line/polyline  nodes (vertices).

See before and after applying the 'smooth($geometry, 5)' function below:-

See after applying the 'smooth($geometry, 5)' function below:-


There are a couple of factors that could cause a lines/polylines to have angular or pointed nodes (vertices). One could be due to the resolution of the drawing, if that is the case then we can adjust the smoothing option to the highest (20000) from the OPTION dialog window.

Another way to smooth the lines is by using the PEDIT command and select FIT.

That is it!

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