written by: Finn Orfano
• edited by: Lamar Stonecypher
• updated: 12/8/2009
Surveying is an important engineering discipline that has a great significance in this modern world where so many technologies are interlinked. Numerous surveying techniques and equipment are used in this discipline.
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What Is Surveying
Surveying is the method of precisely establishing the global or three dimensional locations of some points on the surface of the earth, including the allied angles and distances. These points are used to create land maps and limits for possession or for other requirements of the state. Technologies of geometry, trigonometry, physics, engineering, mathematics, and law are used in surveying. Necessary measurements are taken to determine the relative location of points on the earth surface. Information is obtained by observation and further analysis to establish property boundaries. The land boundaries are established based on record and historical facts. Surveying is an important necessity in the implementation of all types of construction. The normal application of surveying is in the disciplines of building and construction, mapping, communications, and for defining legal limitations of land possession. Other areas where this science is utilized are geology, seabed and coastline mapping for navigation, and bed of water bodies like ocean, river, and lake.
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History Of Surveying
Surveying has always been a crucial factor in the growth of the human community since ancient history. Several surveying procedures have since been used. In the ancient Egypt, after the overflowing of river Nile, the farm boundaries were disturbed. These borders were marked by the use of simple geometry. The precise dimensions, and a true north-south direction of the Great Pyramids of Giza, confirm the existence and use of surveying by the Egyptians. The compass was used to measure the horizontal angles. This device was subsequently improved to provide a more accurate angular data.
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A total station is modern surveying device that utilizes the optical and electronic technology. It is integrated with an instrument called an electronic distance meter for the measurement of distance to a desired point. Several types of this device include a facility to store the measured data, including the distance, and vertical and horizontal angles. The later models can also transmit the data to a computer and create a map of the region being surveyed. The distances and angles are measured, and subsequently the coordinates of the points being surveyed are determined using trigonometry. Highly advanced total stations can measure the angles by electro-optical techniques. The electronic distance meters measure the distance by the use of radio and light waves. The distance is determined by the time variation between the transmitted pulse and the return pulse. Alternatively, it can also be measured by the difference in phase between the transmitted and the reflected beam. The initial total stations were fundamentally optical-mechanical instruments, while the present expertise has advanced to completely electronic technology.