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angle is determined as normally. Thus, all the measurements requisite to locate a point both vertically and horizontally with reference to the point where the tacheometer is centred are determined by an observer at the instrument without any assistance beyond that of a person to hold the level staff.
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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
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to measure the distance between two points on the stadia rod (the stadia interval). This is converted to distance from the instrument to the stadia rod by multiplying the stadia interval by the
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A theodolite is used to measure the horizontal angle between indicators on the two ends of the subtense bar. The distance from the telescope to the subtense bar is the height of an
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In western countries, tacheometry is primarily of historical interest in surveying, as professional measurement nowadays is usually carried out using
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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.
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165:. 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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Another device used in tacheometry to measure distance between the measuring station and a desired point is the
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on the bar enables the bar to be oriented perpendicular to the line of sight to the angle measuring station.
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formed with the theodolite at the upper vertex and the subtense bar length at its base, determined by
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One or more of the preceding sentences incorporates text from a publication now in the
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are multiplicative and additive constants. Generally, the instrument is made so that
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between them. Alternatively, also by readings of the staff indicated by two fixed
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and recorded using data collectors. Location positions are also determined using
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541:. Vol. 26 (11th ed.). Cambridge University Press. pp. 341–344.
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between two well-defined points on the staff and the known distance 2
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is the stadia interval (top intercept minus bottom intercept);
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Other forms of tacheometry in surveying include the use of a
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The formula most widely used for finding the distances is:
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of a fixed point on the staff and the horizontal distance
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normally employed to mark a point, a staff similar to a
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558:, McGraw-Hill Book Company, 1966 LC 64-66263
554:Raymond Davis, Francis Foote, Joe Kelly,
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527:Airy, Wilfrid (1911). "
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331:{\displaystyle d=ks+c}
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420:{\displaystyle k=100}
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394:{\displaystyle c}
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354:{\displaystyle s}
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58:Tacheometry
569:Categories
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276:stadia rod
266:Stadia rod
248:theodolite
240:tachymeter
117:theodolite
32:Tachometry
575:Surveying
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179:subtended
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535:(ed.).
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341:Here,
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