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Models and batch processing

Outcome: replace a repeated manual sequence with a Processing model or batch job whose inputs and outputs are explicit.

Choose a repeatable task​

Good candidates include:

  • clip several contextual layers to one whenua/catchment extent
  • reproject downloaded layers to NZTM2000
  • create slope/hillshade for several DEM tiles
  • extract the same fields from multiple council datasets
  • export several map layers to GeoPackage

Do not automate a poorly understood interpretation simply because QGIS can run it quickly.

Processing history first​

Run the workflow manually once and inspect Processing → History. Confirm every step produces the intended result.

Model Designer​

Open Processing → Graphical Modeler / Model Designer (wording may vary slightly by packaged interface).

Add:

  • model inputs
  • algorithms
  • explicit outputs

Name model components by purpose rather than Algorithm 1.

Example model​

input boundary
   ↓
fix geometries
   ↓
reproject to EPSG:2193
   ↓
clip source layer
   ↓
output GeoPackage layer

For a real project, only include Fix Geometries if input validity is a known issue. Do not make it an unexplained ritual.

Batch processing​

Right-click many Processing algorithms and choose Execute as Batch Process where supported. This is useful for a list of similar rasters or vector files.

Check output naming before running dozens of rows.

Exercise​

Build a small model that accepts a boundary and vector input, reprojects as needed and clips to the boundary. Test it on two public layers.

Record:

  • model name
  • version/date
  • input assumptions
  • output CRS
  • output naming

Check​

  • manual and modelled result feature counts are plausible
  • source layers remain unchanged
  • model has meaningful parameter names
  • temporary/intermediate layers are not mistaken for final data

Next: Terrain and raster analysis.

Official reference: QGIS Processing modeler.

Last reviewed: 26 August 2026

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