ABSTRACT
Geometrical geodesy is the branch of science that deals with the size and shape of the Earth. An important concept in physical geodesy is that a level surface is perpendicular to the plumb line at every point. In geometrical geodesy, the ellipsoid normal is always perpendicular to the tangent to the ellipse. An ellipsoid is the mathematical basis of geometrical geodesy. Although “ellipsoid” and “spheroid,” have essentially the same definition in geometrical geodesy and are often used interchangeably, a distinction can be made. Geometrical geodesy relationships are used extensively when computing geodetic traverses and inverses on the ellipsoid. A two-dimensional (2-D) geodetic traverse is typically called the geodetic forward computation and computing the 2-D direction/distance between points is called the geodetic inverse. The Global Spatial Data Model provides an alternative to classical geodesy methods and can be used to obtain results to any accuracy desired.
