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Buffer Active Layer

QGIS Script · Python

Buffer Active Layer

Expands every feature in the active layer outward by a configurable radius in metres. Place points at tree trunk locations and run this script to get circular crown polygons — ready to feed into the Tree Height Extractor and Canopy NDVI Calculator. Also works on polygon layers for boundary buffer zones. Automatically picks the right UTM zone for accurate metric distances anywhere in the world.

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What you get

buffer_active_layer.py
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Also in the GIS Utilities Pack — 4 scripts for $49 · save $31 vs buying separately

What it does

Points → crown polygons

Place points at tree trunk locations — manually in QGIS or from a GPS field collection. Run with your estimated crown radius and each point becomes a circular polygon. These polygons define the spatial extent per tree and serve as the vector input for Tree Height Extractor and Canopy NDVI Calculator.

Polygons → expanded outlines

Each polygon boundary is pushed outward by the radius with rounded corners. Useful for buffer zones around field boundaries, exclusion rings around structures, or expanding estate polygons.

Accurate metric buffer worldwide

Automatically detects the correct UTM zone from the layer's centroid when the CRS is geographic (degrees). If the layer is already in a projected metric CRS, the buffer is applied directly with no reprojection.

Any vector format, any CRS

Works with GeoJSON, shapefiles, GeoPackages, and any QGIS-supported format. Original attributes are preserved on every output feature.

Tree annotation workflow: GPS points → crown polygons → height + NDVI per tree

  1. 1. Collect or place a point layer at trunk locations. Run this script with your crown radius → one circular polygon per tree.
  2. 2. Run Canopy Mask Generator on your multispectral raster → binary raster that marks only vegetated pixels.
  3. 3. Run Canopy NDVI Calculator — takes the crown polygons (where to sample) + canopy mask (only vegetated pixels) → adds NDVI_median per tree.
  4. 4. Run Tree Height Extractor on the same polygon layer → adds height_m from DSM/DTM.
Canopy Mask NDVI Calculator Height Extractor

How to use it

  1. 1

    Load your vector layer and click it to make it the active layer in the Layers panel.

  2. 2

    Open Plugins → Python Console → Show Editor.

  3. 3

    Paste the script. At the bottom, set buffer_radius in metres.

  4. 4

    Click Run.

Requirements

  • QGIS 3.28 or newer
  • QGIS processing framework — bundled
  • Any active point or polygon vector layer

Also in the GIS Utilities Pack

Get all 4 GIS utility scripts for $49 — save $29 vs buying individually.

View bundle