Web Mercator distortion

global

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.

Detection

Compare cell area computed in Mercator versus a true equal-area or geodesic method; error scales with sec(latitude).

Mitigation

Never compute area/radius in EPSG:3857; reproject to an equal-area or geodesic method first
Reserve Mercator strictly for tile-display rendering, not measurement

Affected conversions

Raster → H3 approximate
H3 → exact polygon exact
H3 → circumscribed circle expansive