Vertical Control Survey: Levelling
摘要
Vertical control refers to surveying techniques that provide measurements to determine the elevation (or height) of geospatial data. In civil engineering, the relief of the terrain is represented by differences in elevation, making this measurement an essential process in the production of vertical data for mapping, engineering design and construction. The process of measuring vertical distances to determine the elevations of given points relative to a given or assumed datum, or to establish points at a given elevation, is called levelling. For Geomatics applied to Civil Engineering, levelling is a typical operation used in the design of roads, railways, tunnels and canals, grade setting works, volume calculations, surveying and implementation of sewerage and drainage systems, and many other types of civil engineering works where elevation values need to be determined. In this sense, this chapter aims to examine the methods and techniques of levelling used in Civil engineering.