Tacheometry

Tacheometry is a system of rapid <a href="/facts/Surveying/qchGcnRC">surveying</a>, by which the horizontal and vertical positions of points on the Earth's surface relative to one another are determined using a tacheometer (a form of <a href="/facts/Theodolite/G4ADP1bC">theodolite</a>). It is used without a <a href="/facts/Surveyor%2527s_chain/C5U3VRMQ">chain</a> or <a href="/facts/Measuring_tape/uBIP6A7v">tape</a> for distance measurement and without a separate <a href="/facts/Level_(instrument)/9HA0E7zQ">levelling instrument</a> for relative height measurements.
Instead of the <a href="/facts/Surveying_pole/WV34ug0h">pole</a> normally employed to mark a point, a staff similar to a <a href="/facts/Level_staff/PxBRjyXq">level staff</a> is used in tacheometry. This is marked with heights from the base or foot, and is graduated according to the form of tacheometer in use.
The ordinary methods of surveying with a theodolite, chain, and levelling instrument are fairly satisfactory when the ground is relatively clear of obstructions and not very precipitous, but it becomes extremely cumbersome when the ground is covered with <a href="/facts/Shrub/X1gKVxL5">bush</a>, or broken up by <a href="/facts/Ravine/aS8FAl19">ravines</a>. Chain measurements then become slow and liable to considerable error; the levelling, too, is carried on at great disadvantage in point of speed, though without serious loss of accuracy. These difficulties led to the introduction of tacheometry.
In western countries, tacheometry is primarily of historical interest in surveying, as professional measurement nowadays is usually carried out using <a href="/facts/Total_station/q4L3FeHK">total stations</a> and recorded using data collectors. Location positions are also determined using <a href="/facts/GNSS/lVgPlF5v">GNSS</a>. Traditional methods and instruments are still in use in many areas of the world and by users who are not primarily surveyors.

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Tacheometry