Meratyn

Manual/Tutorials

Environmental Change Monitoring

This tutorial detects and presents change between two dates of imagery: composites first, a change-detection pass second, and side-by-side plus time-series views for inspection. It uses the Remote Sensing tools, the Raster tools, and three plugins.

1. Load two dates of imagery

Add co-registered imagery for both dates — multispectral GeoTIFFs, COGs, or a streamed source such as the Microsoft Planetary Computer or Earthdata GIS plugins. Same sensor and resolution on both dates keeps the comparison honest.

2. Build composites

Run Processing → Whitebox Toolbox → Remote Sensing → Create Colour Composite for each date. Working from composites (or from DN To TOA Reflectance if the data is still raw DN) removes brightness differences that are not real change.

3. Detect the change

  • Run Processing → Whitebox Toolbox → Remote Sensing → Change Vector Analysis with the two composites as inputs. The output magnitude highlights everywhere the spectral signature moved.
  • For a proper time series (three dates or more), run Processing → Whitebox Toolbox → Raster → Analyze Changes Using CCDC instead.

4. Inspect side by side

Enable the Compare Layers plugin and swipe between the two composites with the change-magnitude layer underneath. Every strong change in the raster should have a visible cause in the imagery — anything else is noise to filter.

5. Add the time dimension

  • The Pixel Time Series plugin plots the history of any pixel you click — use it to confirm that a detected change is persistent and not a seasonal artifact.
  • With a stack of dated rasters, the Timelapse plugin animates the full sequence on a timeline.

6. Present the result

Style the change magnitude with a colormap, mask everything below your confidence threshold, and export the view or record a map video walking through the three biggest changes.

Next steps

  • Convert the strongest change areas to vectors and run Processing → Whitebox Toolbox → Vector → Build Balanced Zones to chunk them for field verification.
  • Publish the swipe view with Export As HTML so stakeholders can inspect it themselves.