Total station (geodesy)

from Wikipedia, the free encyclopedia
Total station from Wild

The total station ( old Gr. Ταχύς tachýs 'fast' and μέτρον métron ' measure ', 'scale') is a device with which horizontal directions , vertical angles and - unlike a theodolite - also the inclined distance (the obliquely measured distance) to the target point can determine. It is used to quickly measure and measure points.

A distinction is made between optical and electronic total stations. In the latter, in addition to electronic measuring modules , an automatic data flow into the storage medium or the evaluation device is also implemented. Special total stations today have an automatic target acquisition or even target tracking , which is based on the miniaturization and operating speed of electronic components and optical CCD sensors .

Optical total station

Optical total stations are divided into non-reducing optical total stations and self-reducing optical total stations:

Non-reducing optical total station
With the total station theodolites (low and medium accuracy range), sections are optically read on a leveling rod with the help of distance lines that are part of the crosshairs on the reticle, and the inclined distances are then derived from them. The horizontal directions and vertical angles are read off as with the theodolite. The inclined distance is determined in the same way with the total station buses . With leveling total stations , the horizontal distance can be read directly from the leveling staff because of the horizontal sight.
Self-reducing optical total station
You are able to automatically reduce the distance to the horizontal. Reduction total stations are, for example, sliding, chart or double image reduction total stations.
Optical-electronic total station
They are a combination of an optical theodolite with an attached or integrated electro-optical distance meter. The direction is read off optically on a horizontal circle. With some devices this pitch circle division can also appear in digital form. The distance measurement is realized with an electro-optical distance meter. The scope of such a distance measuring device can correspond to that of the electronic total stations. The height measurement is usually carried out trigonometrically . The height difference is calculated from the zenith angle and the inclined section or the horizontal section.

Electronic total stations (total stations)

functionality

Electronic total stations measure the directions automatically after targeting, the distances are determined by electronic distance measurement . Either only the transit time or, in the case of more precise total stations, the transit time and phase shift of an emitted light beam reflected at the target point is measured. The light of the carrier wave lies in the infrared range or in the near infrared of the light spectrum. The reflection of the light beam at the target point takes place in a targeted, retroreflective triple prism (see triple mirror , ranges up to 10 km depending on size) or on reflective foils (range a few hundred meters).

Modern total stations are optionally equipped with laser rangefinders that can measure almost any surface without a reflector. The range and accuracy of these so-called DR measurements (direct reflex) are, however, somewhat less than those of the above. Infrared measurement on a triple mirror, which is why both methods are used side by side. The decisive factor for the range and accuracy is mainly the nature of the targeted surface in terms of its reflective properties (so light surfaces are far better suited than dark ones). The different total station series from the various manufacturers offer ranges from 15 to just over 2000 m, depending on the device class.

Data processing

The measurement value determination (direction and distance) takes place fully automatically and electronically. Computers are usually connected for data storage. In modern total stations, processing programs and corresponding memories are often integrated. The data (three-dimensional measuring points) can immediately be mapped two-dimensionally (e.g. building survey of facades / floor plans) or three-dimensionally with the appropriate computer programs and exported as a dxf file. Usually, however, a 3D model is generated, since data can be reduced to two-dimensional with any CAD program at a later point in time.

Motorized total station

The latest generation of total stations has electrically driven side and elevator drives. These enable, among other things, the automatic aiming of the triple mirror and target tracking. In addition, a total station can measure a predefined series of several points fully automatically. In this way, for example, the deformations of the arch dam of the Lai da Nalps , which could result from the construction of the Gotthard Base Tunnel, are monitored .

In the so-called "one-man operation" the user can be saved on the device, and the operation is only done from the reflector. The motorization plays a major role here, as the device must continuously track the reflector. In order to make it easier to find the measuring prism at the beginning, the total station must have a so-called "target search". While one-man stations of the first generation consistently had long search times, modern devices have additional sensors that help in finding a destination. Topcon developed an infrared-controlled search that restricts the measuring range and also allows measurements on multiple channels. As a result, when working with several reflectors, it is not always the one closest to the total station with the greatest signal strength that is tracked, but the one with a certain frequency, so the important clear assignment between total station and reflector takes place. The manufacturer Trimble generates the clear target assignment using an active prism in which a diode ring is detected by a quadrant sensor.

Imaging total station

The total station of the future will rely on the use of image information during measurement. The measurement image is used on the one hand for documentation purposes, on the other hand it can be actively integrated into the measurement process. The aiming of the points no longer has to be done via the eyepiece, but can be done directly in the image. Digital zoom or even optical enlargement functions also enable precise details. The measurement can be carried out directly from the total station or from the field computer or PC via WLAN. Measured objects and points that are displayed in the live image help to maintain clarity. Built-in scanning functions make it possible to scan objects to be measured over a large area and thus help to create realistic 3D photo models.

In one-man operation, where the total station is operated from the reflector, the live image recorded by the total station is transmitted to the field computer via WLAN, which enables, for example, image-assisted staking out. Among the imaging total stations, the Leica TS15, Trimble VX and Topcon Imaging Station (IS) can be mentioned, whereby only the latter has an optical magnification and a coaxially arranged camera.

Device manufacturer

See also

literature

  • Bertold Witte , Peter Sparla: Surveying and the basics of statistics for the construction industry . 7th edition. Wichmann, 2011, ISBN 978-3-87907-497-6 .
  • Heribert Kahmen: Applied Geodesy: Surveying . 20th edition. Walter de Gruyter, 2006, ISBN 3-11-018464-8 .
  • Günter Petrahn: Basics of surveying technology. Paperback surveying. 5th edition. Cornelsen Verlag, Berlin 2010, ISBN 978-3-464-43335-5 , p. 251 ff.

Web links

Commons : Total station  - album with pictures, videos and audio files

Individual evidence

  1. ↑ Günter Petrahn: Basics of surveying technology. Paperback surveying. 5th edition. Cornelsen Verlag, Berlin 2010, ISBN 978-3-464-43335-5 , p. 251.
  2. ↑ Günter Petrahn: Basics of surveying technology. Paperback surveying. 5th edition. Cornelsen Verlag, Berlin 2010, ISBN 978-3-464-43335-5 , p. 251 ff.
  3. ↑ geodimeter - The First Name in EDM. Professional Surveyor Magazine, 1999, accessed April 12, 2013 .
  4. ↑ Discover Spectra Precision key milestones! Timeline. Spectra Precision, November 10, 2012, accessed April 12, 2013 .