Ground-Based Positioning Techniques
The positions of objects, which include topographical features and man-made structures on and below Earth’s surface or under water, can be determined by various techniques. These techniques include photogrammetry and remote sensing, satellite positioning, hydrographic surveys, and terrestrial survey techniques (also called ground-based surveys). The first three techniques are discussed separately in later chapters. This chapter presents only ground surveying techniques, i.e., the measurement of angle, azimuth, distance, and height difference to obtain the position of an object using equipment placed at ground level. To inter-relate all the position information collected by different techniques or from different locations, this information must be referred to a common coordinate system. There are several coordinate systems in use, some of which are globally adopted, while others are locally defined. Their definitions and transformations are discussed in Chapters 2, 3, and 4.
KeywordsHeight Difference Total Station Differential Levelling Vertical Angle Digital Level
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