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Incorrect ring winding order
GeoJSON requires exterior rings counter-clockwise and holes clockwise (right-hand rule); reversed winding flips interior/exterior for winding-sensitive fillers.
Class
Case to account for
Affects
3 conversions
01
Detection
Compute signed area (shoelace formula); sign mismatch against RFC 7946 convention for the ring role.
02
Mitigation
01
Normalize winding on ingest (rewind exterior CCW, holes CW)
02
Validate with a strict GeoJSON linter before filling
03
Affected conversions
PolygonH3 (center-contained)
OPENPolygonH3 (fully-contained)
OPENPolygonH3 (intersects)
OPEN