Geodesy: A field of engineering science that is concerned with the determination of the size and shape of the Earth and its gravity field together with their variation over time. Today many of the fundamentals of geodesy are accomplished using advanced space techniques such as the Global Positioning System (GPS), Satellite Laser Ranging (SLR) and Very Long Baseline Interferometry (VLBI). These techniques are capable of measuring distances of some thousands of kilometres to an accuracy of a few millimetres.
Geodesy is the basis of any mapping aids projects including navigating in the sea , air and land. Areas of its applications cover global problems such as monitoring vertical and horizontal movements of the earth, measuring change in sea level due to the 'greenhouse effect', measuring variations in the rotation axis and rate of rotation of the Earth, to more local problems from measuring the micromovements of bridges, dams and other structures, to the real-time alignment of roads and railway tracks.
Basics and Reference
Collections of Links
Precise Geodesy with GPS
Coordinate Systems
Space/Satellite Geodesy