Glossary for Geospatial Science

geoid:� The figure that represents the irregular spheroidal shape of the earth is called the geoid.� The geoid is an equipotential surface (which means the direction of gravity is perpendicular to all points on the surface) at mean sea level.� Because of variations in the distribution of the mass and density of the earth�s constituents, the geoid generally rises over the continents and is depressed in oceanic areas ;� the geoid also conforms to various lumps and depressions that depart from average smoothness on the earth�s surface.� For mapping purposes, the attributes found on the geoid must be transferred to a more regular geometric surface, an ellipsoid.