Reference Ellipsoid

A reference ellipsoid is a mathematically defined, smooth, and nearly spherical shape that models Earth's overall size and shape. Since Earth isn't a perfect sphere but slightly flattened at the poles and bulging at the equator, the ellipsoid provides a standard, consistent way to measure and map locations across the globe. It serves as a baseline for geographic coordinate systems, GPS, and mapping tools, enabling precise positioning and navigation by offering a simplified, uniform reference against Earth's complex surface variations.