Geodetic Surveying: The Next Decade

By the end of the next decade (1988), most large-area geodetic surveys will probably be made using a satellite Doppler positioning system, an inertial positioning system, or some combination of the two systems. The Doppler system is capable of determining the absolute, three-dimensional position of any point on the earth and it can also be used to obtain relative positions. Using data from multiple satellite passes and refined data reduction techniques, it is possible to obtain accuracies of 20 cm or better. The development of the Global Positioning System (GPS) in the 1980's is expected to improve position accuracies to 10 cm or better. The inertial system is capable of very large, rapid surveys with position accuracies of 20 cm or better relative to the control used. In addition, deflections of the vertical to one second of arc and gravity anomalies to one milligal can also be obtained. Despite relatively large costs, both systems have proven to be cost-effective because of their very high productivities.