Web Mercator scheme (EPSG:3857): a SINGLE square root tile covering the world in
both axes (latitude clamped to ±WEB_MERCATOR_MAX_LATITUDE), quartered per
level. Tile rows are equal steps in the Mercator Y, so their geographic latitude
bands narrow toward the poles (unprojected here via the inverse Gudermannian).
Web Mercator scheme (EPSG:3857): a SINGLE square root tile covering the world in both axes (latitude clamped to ±WEB_MERCATOR_MAX_LATITUDE), quartered per level. Tile rows are equal steps in the Mercator Y, so their geographic latitude bands narrow toward the poles (unprojected here via the inverse Gudermannian).