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Geodesic versus planar geometry
Buffer, distance, and intersection operations computed on raw lat/lng as if it were a flat Cartesian plane diverge measurably from true great-circle geometry, worsening with distance and latitude.
Class
Case to account for
Affects
4 conversions
01
Detection
Compare planar buffer/distance output against a geodesic (e.g. Vincenty/haversine) computation for the same inputs; diverging error grows with radius and |latitude|.
02
Mitigation
01
Use geodesic buffering/distance libraries (e.g. turf with units, or explicit ellipsoidal projection) for any radius beyond a few km
02
Document the max latitude/radius where planar approximation is acceptable
03
Affected conversions
Point+radiusH3
OPENH3inscribed circle
OPENH3circumscribed circle
OPENLine/corridorH3
OPEN