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Point cloud annotation

The Point Cloud Annotation plugin labels LiDAR points with ASPRS classes directly on the map. Use it to fix misclassified points (for example, stadium seating left as "never classified") or to build training labels for point cloud segmentation models. It is the first slice of the plan tracked in opengeos/GeoLibre#2749.

Start a session

  1. Load a point cloud with Add Data → LiDAR Layer (LAS, LAZ, COPC, or EPT).
  2. Zoom to the area you want to label. A COPC or EPT cloud streams by level of detail, so the session holds the points loaded at the current view: zoom in further to label at full density.
  3. Open Plugins → Point Cloud Annotation, pick the cloud, and choose Start annotating.

While a session runs, the plugin colours the cloud by classification and pauses streaming, so no edited point is dropped when you move the map. Scroll to zoom and right-drag to tilt or rotate as usual.

Select and assign

  • Box (B) and Lasso (L): drag on the map to select points. Hold Shift to add to the selection or Alt to remove from it, or pick a mode in the panel. Pan returns left-drag to moving the map.
  • Selection goes through all depths, like a camera frustum. Narrow it with the Min Z / Max Z filter (metres) or Only points in class, which relabels just the points currently in one class.
  • Hidden classes (toggled in the LiDAR panel's legend) and points outside the LiDAR panel's elevation filter are never selected.
  • Selected points are drawn in yellow. Choose the class to assign and press Apply (Enter); Clear (Esc) drops the selection. Clicking a row in Classes in session makes it the class to assign.
  • Undo and Redo step through the class assignments of the session.

Export

Edits live in memory, so export before finishing the session:

  • LAS 1.4 writes every point loaded in the session (point format 7 with RGB, or 6 without) with its edited class, intensity, returns, GPS time and scan angle. Coordinates are written back in the source file's CRS, feet included, when its WKT is known, and in WGS 84 otherwise.
  • Segments.ai JSON writes a pointcloud-segmentation label. Its point_annotations line up point for point with the LAS file, one annotation per class with category_id set to the ASPRS code.

Finish session resumes streaming. Streaming may evict edited points once you move the map, which is why labels need to be exported first.

Limitations

  • MapLibre renderer only.
  • Labels are not saved in the project yet, and LAZ/COPC output is not available (the browser has no LAZ encoder); convert the LAS with PDAL or laspy if you need compression.
  • Cuboids, instance labels, and assisted pre-labeling are later phases of #2749.