Powerpoint

Ellipsodal and Datum• The reference ellipsoid, also known as a spheroidis an approximated shape of the earth is the basisof horizontal control in making maps.• The placement of a coordinate system upon theellipsoid is determined by a horizontal referencestarting point or datum.• There are a number of ellipsoids/datums used indifferent parts of the World because the Earth isnot consistent in its shape – the Earth is lumpy!