Space polygon
A spatial polygon (also spatial polygon ) is a geodetic polygon which solves the position and height determination in three dimensions .
description
In the classic polygon of engineering and cadastral surveying , the position (coordinates x, y) is processed on one plane , while the height measurement is evaluated in a separate operation. Although this is much easier to carry out, it has small disadvantages for special measurements.
calculation
The calculation of measured horizontal angles , distances and zenith distances (see theodolite and EDM ) in a spatial model, however, requires the knowledge of the perpendicular deviation , since the theodolite axis is always set exactly in the vertical , the coordinates x, y are based on a mathematical (not real ) Earth ellipsoid . This increases the effort involved in creating 3D models considerably, but the achievable accuracy is also higher, and the calculated height differences of the measuring points correspond to modern theoretical requirements.
Ramsayer
Karl Ramsayer was the first to introduce this approach to geodesy (TU Stuttgart, around 1970). The methods of satellite geodesy around 1990 also made other 3D methods possible that do not refer to the plumb line. However, water can flow between two points of the same height if they are GPS heights.