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Documentation of QGIS Python plugin brdrQ: FeatureAligner

Instructions

  1. Choose the settings for the alignment (reference layer,…)
  2. Select the thematic layer you want to align.
  3. Select a feature from the list or via ‘Select feature(s) on map’.
  4. View the prediction(s) for this aligned feature.

Additionally, you can:

  • Switch between multiple predictions (via list, slider, or spinbox).
  • Plot: Request a ‘plot’ of these predictions (relevant distance (m) vs. change (m²)).
  • Visualize: Visualize the predicted relevant distances side by side.
  • Save Geometry: Adjust the original geometry to the chosen prediction.
  • Reset Geometry: Reset the original geometry (only within a feature session, so if no other feature is selected).

Parameter Guide

Reference layer

  • Definition: Target dataset used as geometric truth.
  • Why use it: Determines what ?aligned? means.
  • Choices: Local/project reference or on-the-fly sources.
  • Impact: Reference quality controls final alignment quality.

Open Domain Strategy

  • Definition: Handling rule for geometry parts outside reference coverage.
  • Why use it: Reflects policy on non-covered area retention.
  • Choices: Exclude/keep/snap variants.
  • Impact: Changes whether external areas are removed, kept, or reshaped.

Processor

  • Definition: Algorithm backend selector.
  • Why use it: Optimizes runtime by geometry type.
  • Choices: AlignerGeometryProcessor recommended.
  • Impact: Better defaults improve speed and consistency.

Threshold value (%)

  • Definition: Fallback threshold in uncertain relevance cases.
  • Why use it: Prevents unstable candidate acceptance.
  • Choices: usually around 50, adapt per dataset.
  • Impact: Higher means stricter matching.

Maximal relevant distance (m)

  • Definition: Maximum deviation searched for predictions.
  • Why use it: Controls correction aggressiveness.
  • Choices: low/medium/high according to data drift.
  • Impact: Larger values increase candidate range and ambiguity.

Add brdr_metadata?

  • Definition: Adds rdr_metadata to results.
  • Why use it: Preserves lineage for downstream updates/audits.
  • Choices: enabled/disabled.
  • Impact: Better traceability with small storage overhead.

Full Reference Strategy

  • Definition: Preference for full-overlap candidates.
  • Why use it: Raise confidence in selected predictions.
  • Choices: ONLY_FULL_REFERENCE, PREFER_FULL_REFERENCE, NO_FULL_REFERENCE.
  • Impact: Stricter mode improves certainty but may reduce alternatives.

Snap Strategy

  • Definition: Snap strictness to reference vertices (mainly line/point workflows).
  • Why use it: Controls structural precision at vertices/endpoints.
  • Choices: NO_PREFERENCE, PREFER_VERTICES, PREFER_ENDS_AND_ANGLES, ONLY_VERTICES.
  • Impact: Stricter snapping improves topological control but can reduce feasible matches.