Generalize Polygons
Plugin ID: 4855
Topology-preserving polygon simplification using the weighted Visvalingam algorithm — no slivers, no gaps.
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Reduces the vertex count of polygon layers while preserving shape and topology.
Shared borders between adjacent polygons are simplified exactly once, so both
neighbours always receive the same simplified edge. This guarantees that no
slivers, gaps, or overlaps are introduced — a property not provided by most
standard simplification tools.
The algorithm is based on the weighted Visvalingam-Whyatt method as used in
MapShaper (mbloch/mapshaper). Triangle areas are weighted by the angle at the
centre vertex, so nearly-collinear points are removed first while
geometrically significant vertices are protected.
Processing runs as a QGIS background task, so the interface stays responsive.
A progress bar in the status area tracks the three internal phases (topology
build, simplification, reconstruction), and the task can be cancelled at any
time via the QGIS task manager.
