Make valid
A repair step that converts invalid polygons into valid geometry, often by splitting or reshaping boundaries.
Category: Topology · Also known as: ST_MakeValid, make_valid
Definition (expanded)
Make-valid operations are common in PostGIS (ST_MakeValid), Shapely, and GIS tools. The output may be a MultiPolygon or GeometryCollection if the original shape is self-intersecting or ambiguous.
Related terms
Valid geometryA geometry that follows topological rules (closed rings, no self-intersections, properly nested holes, etc.).Self-intersectionWhen a polygon boundary crosses itself (a bow-tie shape), often making it invalid.MultiPolygonA geometry containing multiple polygons (parts), each with its own exterior ring and optional holes.GeometryCollectionA single geometry that contains multiple geometries, which can be different types (Polygon, MultiPolygon, etc.).