School of Forest Resources and Conservation		UF / IFAS
	GEOMATICS AREAS OF STUDY
Areas of Study Geomatics Faculty Research Fall Courses Spring Courses Facilities Image from NASA	GEODESY is the branch of Earth sciences that deals with the division of the Earth. It deals with the geometric and the physical Earth in order to determine its size and shape and its gravity field. Geodesy is closely linked to surveying and mapping. Surveying and mapping professionals use planimetric flat Earth models for planimetric projects which comprise small areas. When the project area gets larger (usually larger than 20 km by 20 km), geodetic implications of a spherical/ellipsoidal Earth model becomes more relevant. The land ordinance of 1785 is a good example of how geodesy affects the surveying and mapping practice. The ordinance reads “… divide territory into townships of 6 miles square by lines running due north-south lines, and others cross at right angles.” The USPLSS was designed to be rectangular. However, due to the complexity of the Earth’s shape as in the convergence of meridians, a rectangular system was un-realizable on the ground. Corrections, using geodesy, were applied to account for the differences. Angles and distances are measured by survey/geodetic equipment to determine locations of points on the surface of the Earth. Geodesy has two main branches, geometric and physical. Geometric geodesy handles positioning problems on the surface of the Earth using a spherical/ellipsoidal model. Satellite geodesy and geodetic astronomy, where either Earth orbiting satellites or celestial bodies are used to locate points on the Earth’s surface, are considered two sub-branches of geometric geodesy. Physical geodesy, on the other hand, studies the Earth’s gravity field to determine the Geoid and other equipotential surfaces. Physical geodesy models tie the mathematical model of the Earth to survey measurements. The Geoid, considered a best fit to the mean sea level, is also the datum for leveling heights. Both geometric geodesy and physical geodesy handle time-dependent variations of the coordinate systems caused by the Earth rotation, polar motion, and other perturbations. Geodesy as an Earth science is a corner stone in other Earth sciences like geography, geology, geophysics, oceanography, and glaciology. Geodesy as an applied science and technology lends itself to engineering, informatics, and professional surveying and mapping.
	Last updated: 1/9/08 - Comments and suggestions welcome - webmaster