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Quickstart

A first change map, and then a first classified one. Ten minutes on a small area.

The panel is three numbered steps. Each opens as you finish the one before it, and each step's header keeps the answer you gave it, so a folded step still tells you what it is holding.

1 · Area, years and output

Try this area

New to it? Zoom to around 49.67°N, 125.29°W on Vancouver Island — paste that into QGIS's coordinate box at the bottom, or search a nearby place — then draw a box a few kilometres across, pick 2019 and 2024, and press Make change map. It's active forestry, so there's real cutblock change to see. A rough box is fine.

Draw area on map, then drag a rectangle.

A line under the button tells you what that area will cost before you commit to it:

Area ~12×12 km · 6 tiles · 0.8 GB to read · ~1 min · output 1.4 Mpx

Give it a Name if you like; its layers go into a QGIS group of that name.

Pick From and To years (2017–2025), and a Detail. Leave Detail at 10 m (full) for a small area — see Detail, resolution for when to change it.

Set Save to: if you want to keep the results. Leave it empty and the run is scratch, discarded when QGIS closes.

Press Make change map. Tiles fill the canvas as they land. Cancel stops after the current tile — finished tiles are kept, so re-running resumes rather than restarting.

Look at the imagery first

The Reference imagery strip at the bottom streams Sentinel-2 cloudless mosaics, one button per year. This is useful for checking which year a change actually appeared in!

2 · Change map

You now have two layers: the change map, and a data coverage layer beneath it.

The coverage layer provides an understanding of areas which may not have had full coverage - thus resulting in an empty change map.

The change map itself can be adjusted on the fly. Move Changed if ≥ to set the cutoff. Auto picks a cutoff for the whole mosaic (Otsu).

That is a complete change map. If that is all you wanted, Export has Plain polygons and Save as GeoTIFF… and you are done.

3 · Objects and classes

Generate Embedded Vector Set cuts everything above your decided threshold into objects and gives each one the embedding of what it covers. min size drops speckle — 1 ha is a sensible start.

Then:

  1. Add a class with the + button. In Transition mode it asks for From and To, so the class is named for the change — forest → clearing. Fill only the first box for a plain name.
  2. Turn on Label by clicking the map and click a few objects. Right-click removes a label.
  3. Everything else is classified as you go — one labelled object is enough to start.

The readout under the buttons shows what the classifier makes of the selected object, one bar per class. A road cutting through a cutblock scoring high on both is the classes overlapping, not the model failing — and seeing that is the point.

The per-object readout: one bar per class, the ones that cleared their own confidence bar in bold.

Step through moves you object by object. Least certain first puts the unknown ones at the top, then the close calls, and skips anything you have already labelled. Pick a class in the list and the filter offers Only "cutblock" to walk just that one.

Use the Inspect button beside the colour chip to click an object and read its scores without labelling it.

Unknown is a real answer

An object the classifier will not commit to stays unknown rather than being forced into the nearest class. That is deliberate. If desired, tick Prefer a best guess over 'unknown' under the ⚙ button to force a class on everything.

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