Used by the apparatus and testing methods to determine the elevation of the ground point methods can be divided into water Zonghuai measurement, trigonometric leveling, and other physical elevation measurements (such as hydrostatic level measurement, pressure measurement height). Now with GPS global satellite positioning system can also direct determination of the high ground point of the earth, and regarded as the ground point of elevation. However, the most commonly used method for leveling, also known as the standard measurement geometry.
         Standard measurement method is to use Levels to provide the level of attention, observation points on the ground to erect the standard of scale, respectively, on the scale reading to read to the projection of the elevation difference between two points. In this way, from a known point of elevation of the ground can be estimated at any point in the ground elevation.