Mapping Toolbox

Spheres, Spheroids, and Geoids

Although the Earth is very round, it is an oblate spheroid rather than a perfect sphere. This difference is so small (only one part in 300) that modeling the Earth as spherical is sufficient for making small-scale (world or continental) maps. However, making accurate maps at larger scale demands that a spheroidal model be used. Such models are essential, for example, when you are mapping high-resolution satellite or aerial imagery, or when you are working with coordinates from the Global Positioning System (GPS). This section addresses how the Mapping Toolbox accurately models the shape, or figure, of the Earth and other planets.

Understanding Geospatial Geometry

Geoid and Ellipsoid