Smooth Contour Generator

Generates smooth, cartographic-quality contour lines from a drone DTM. Applies Gaussian smoothing to remove the faceted mesh artefact, then smooths the lines with Chaikin's algorithm. Major contours are labelled with elevation in metres.

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What you get

generate_contours.py

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What it does

Gaussian smoothing

Applies a Gaussian filter to the DTM raster before contouring, removing the triangular mesh artefact common in drone photogrammetry outputs.

Chaikin's line smoothing

Smooths the contour lines themselves by iterative corner-cutting, removing the stepped polygon appearance of raw QGIS contours.

Major/minor styling

Every Nth contour is drawn thicker and labelled with its elevation in metres. Minor contours are drawn thin.

Configurable interval

Set any contour interval in metres and choose how often major (labelled) contours appear.

How to use it

1
Load your DTM raster into QGIS. Layer name must contain dtm.
2
Check (tick) the DTM in the Layers panel.
3
Open Plugins → Python Console → Show Editor.
4
Paste the script. Set interval (metres between contours) and major_interval (every Nth is thick and labelled).
5
Click Run.

Requirements

QGIS 3.28 or newer
numpy, scipy, osgeo.gdal — bundled with QGIS
DTM raster — layer name contains "dtm"

Also in the Terrain Analysis Pack

Get all 6 terrain scripts for $35 — save $15 vs buying individually.

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