# measurement

Center of the official surveying of the canton of Zurich since 1912, Brütten , Switzerland
Field book frames - tools for surveyors

Surveying is used on the one hand as a synonym for geodesy , on the other hand for the measurement of certain variables, in particular the recording of the actual and legal existence of parts of the earth's surface. "Measurement" is understood to mean the quantitative recording of a geometric variable (e.g. distance, angle, height) and "measurement" is the entirety of all measurements required to record an object ( property , building, street, etc.).

Surveying is generally the metrological recording of points on the earth's surface, in rooms or on objects that are required for a specific purpose. It is used in particular for the complete new recording and mapping of areas.

In the German administrative structure, terrestrial surveying is the task of the cadastral administration to document boundaries and to determine the properties of the terrain.

The technical and mathematical methods of surveying are described under geodesy .

## Engineering surveying

Engineering surveying is the sub-area of ​​surveying that is required for the construction of complex structures such as buildings, bridges , roads, tunnels or power plants . Tasks include the determination of dimensions, staking out building axes and heights, settlement measurements during the construction work and control measurements during construction.

## Land survey

The national survey is concerned with the mapping of the environment, especially for the creation of topographic maps (1: 10,000 to about 1: 200,000) and with the creation of a nationwide surveying network from points known in terms of coordinates. Until a few years ago, the latter was carried out using optical trigonometric measurements, but over time the coordinates of the network points are increasingly determined using satellite-based measurements ( GPS , GNSS ).

In contrast to cadastral surveying, the curvature of the earth's surface must be taken into account for optical measurements over long distances , and the theories of higher geodesy for precise height determination .

In the cadastral survey, legal boundaries are determined or proven and the development of the land is determined. The data are used to create full-scale maps and ownership registration and used to secure the ownership of real estate and furthermore for the continuation of the cadastral . The land map is continued through, for example, new borders or newly measured buildings.

## Zoning

There are two forms of land management: in rural areas this is land consolidation , in populated areas it is (building land) reallocation .

Land consolidation is used when a reorganization of the rural land is necessary (fragmentation) or areas have to be used on a larger scale (road construction). This procedure is carried out by the Office for Rural Reorganization or the Office for Rural Development in Bavaria. The reallocation of building land is usually carried out by the land surveying offices of the cities or by the land registry offices belonging to the district administrations.

## Mountain surveying

The surveying work in mining is generally referred to as mountain surveying . These can be both underground cavities that were created for mining purposes, as well as opencast mines for surface mining. The surveying work in mining is carried out by land separators , mountain surveying engineers or mountain surveying technicians.

## Hydrographic surveys

As hydrographic surveying the shape and depth determination is a body of water (lake, river and stream bed designated waters, estuaries, gravel banks, etc.). It is carried out with survey ships or boats through a suitable combination of position and depth measurement.

Changes to the water floor also require regular new measurements, e.g. B. the sedimentation in reservoirs or at river mouths and the determination of the mass for dredgers .

## Ship surveying

Ship measurement is the determination of the volume of a seagoing ship.

## Satellite surveying

Special tasks are the orbit measurement of satellites from the earth's surface and the measurement of the earth's surface from satellites. With the introduction of long-term observation of satellite signals from orbiting satellites for navigation, classic terrestrial surveying with devices has increasingly changed to satellite-supported surveying of the earth's surface ( GPS ).

## Astronomical survey

Specialized areas of surveying deal with topics of the trajectories of celestial bodies with the background of earth-related, near-earth or remote tasks. The astronomical determination of the direction of the plumb bob , of precise directions ( azimuths , radio masts, etc.) and geographical coordinates are also special applications of geodesy.