Measuring point

The title of this article is ambiguous. Further meanings are listed under measuring point (disambiguation) .

As a measurement point designate technicians and scientist the exact position of a measurement. As a rule, it is specified in the form of coordinates in meter to millimeter accuracy:

• two-dimensional (on a surface) e.g. B. in Gauss-Krüger coordinates x, y
• three-dimensional (in 3D space) z. For example, by latitude B , length L and height H .
• In so-called 2 ½ D - databases elevation is not as a coordinate, rather than attribute out.
• For large-scale measurements (e.g. astrometry in the solar system, geophysics , for satellite stations or in space travel ), 3D positions are also used as Cartesian coordinates ( X, Y, Z ).

Measuring points in science and technology

Measurements are carried out in almost all fields of knowledge and many technical applications. Here, an exemplary overview should show in which areas the point-like definition of measurements, samples or surveys is particularly important. Only in the humanities is this not the case.

• Geosciences : precise definition of points in geodesy (earth measurement, surveying) and in construction (0.1 to 10 mm), followed by geophysics , hydrography and soil science (cm to meters), geology , meteorology and environmental protection (approx. Meter accuracy) and geography (m to km).
• Life sciences : Databases for bioindicators approx. Meters, test and sample areas in forestry and agriculture approx. 1–10 meters, distribution maps and immission measurements approx. 100 to 1,000 m.
• Medicine : depending on the subject, millimeters to decimeters, but mostly defined as a measuring point on the body or marked on the body (e.g. before operations).
• Technology : particularly numerous measurement points or point clouds in the design or control of machines , car bodies , aircraft, etc. (from 0.1 to 10 mm); less in mines and in tunnel construction (point definition as in geodesy to the millimeter to centimeter), building and civil engineering 0.1 mm (dams, bridges, canals) to a few centimeters (residential buildings) depending on the object.

Related meaning

The term is also used to mark the measuring point - a stable, centimeter-accurate marking of the position on an object or the surface of the earth , for example by means of a cross mark , line cross, dots of color, boundary stone or rock mark. In the case of geodetic surveying points , the position of the measuring instrument in the ground is marked by a TP stone , metal measuring mark (pipe, nail), a removable rod signal or leveling or tower bolts .

The coordinates of the measuring points used and the measured values themselves are - depending on the subject - stored in special lists, directories or, today, mostly in databases . The coordinates and measurement data also include additional information such as point number, classification, date and time of the measurement (s), external circumstances, measuring device, observer, etc.

Difference to measuring points and sample points

The term measuring point is generally defined more broadly than the measuring point , but is used somewhat less often. In contrast to the measuring point, the position of the measuring device or sensor is often not specified in rectangular coordinates, but on streets or rivers as kilometrage , or in measurements on buildings relative to this.

Austrian and southern German geoscientists use the term test area when z. B. in soil science , botany or in test forests instead of individual measuring points, the average of several sample points is collected. Such areas, on which marked sample trees or grid-like drilled soil samples are measured, have dimensions between 1 ar and 1 ha , depending on the subject .

See also

• Tape measure , control measure
• Measuring point
• Fixed point , polygon point , point cloud
• Topocenter , eccentric

literature

• Norbert Bartelme: Geoinformatics: models, structures, functions . 4th edition, Springer 2005.
• Brockhaus, keyword groups measuring, test and sample
• Heribert Kahmen : Surveyors . 18./20. Edition, De Gruyter-Verlag, Berlin 1993/2005.
• Nicholas MS Rock: Numerical Geology . Springer, Berlin / Heidelberg / New York 1988.