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This ratio is known as the stadia constant or stadia interval factor. Thus the formula for distance is D = kS. where D is distance from the telescope to the rod; k is the stadia constant; S is the difference between the rod readings at the two stadia marks; For example, a typical stadia mark pair are set so that the ratio is 100.
The interval between stadia marks in most surveying instruments is 10 mrad and gives a stadia interval factor of 100. The distance between the instrument and a stadia rod can be determined simply by multiplying the measurement between the stadia hairs (known as the stadia interval) by 100. The instrument must be level for this method to work ...
A level staff, also called levelling rod, is a graduated wooden or aluminium rod, used with a levelling instrument to determine the difference in height between points or heights of points above a vertical datum.
A wooden tripod holding an optical level is set up firmly on the ground. Levelling or leveling (American English; see spelling differences) is a branch of surveying, the object of which is to establish or verify or measure the height of specified points relative to a datum.
Stadia mark, crosshairs on the reticle of a theodolite or other surveying instrument Stadiametric rangefinding (also stadia method), a technique of measuring distances with a telescopic instrument Stadion (unit) (plural: stadia), an ancient Greek unit of length
Wild brand subtense bar. Another device used in tacheometry to measure distance between the measuring station and a desired point is the subtense bar. [2] This is a rigid rod, usually of a material insensitive to change in temperature such as invar, of fixed length (typically 2 metres (6.6 ft)).
A direct-readout theodolite, manufactured in the Soviet Union in 1958 and used for topographic surveying. A theodolite (/ θ i ˈ ɒ d ə ˌ l aɪ t /) [1] is a precision optical instrument for measuring angles between designated visible points in the horizontal and vertical planes.
The complete unit is normally mounted on a tripod, and the telescope can freely rotate 360° in a horizontal plane.The surveyor adjusts the instrument's level by coarse adjustment of the tripod legs and fine adjustment using three precision levelling screws on the instrument to make the rotational plane horizontal.