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Web Mercator distortion
Web Mercator (EPSG:3857) inflates area and distance with latitude (infinite at the poles); using tile-based Mercator coordinates for area/radius math biases high-latitude markets.
Class
Case to account for
Affects
3 conversions
01
Detection
Compare cell area computed in Mercator versus a true equal-area or geodesic method; error scales with sec(latitude).
02
Mitigation
01
Never compute area/radius in EPSG:3857; reproject to an equal-area or geodesic method first
02
Reserve Mercator strictly for tile-display rendering, not measurement
03
Affected conversions
H3exact polygon
OPENH3circumscribed circle
OPENRasterH3
OPEN