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Which instrument is used in optical method?
Chain and tape
Telescope and staff
D.M
All of the above
Telescope and staff
In surveying, optical methods rely on line-of-sight instruments to measure distances, heights, or angles. A telescope and a leveling staff are the fundamental components used in optical leveling and tacheometry to determine vertical and horizontal displacements by optical observation.
In surveying, optical methods rely on line-of-sight instruments to measure distances, heights, or angles. A telescope and a leveling staff are the fundamental components used in optical leveling and tacheometry to determine vertical and horizontal displacements by optical observation.
D=Ks+C — The basic tacheometric formula where K=if
Elevation=HeightofInstrument−StaffReading — Fundamental principle of optical leveling
The principle involves the use of a telescope to sight a graduated staff. By observing the readings intercepted by the horizontal cross-hairs of the telescope's reticle, the observer can determine relative elevations (leveling) or, in the case of stadia tacheometry, compute horizontal distance using the formula D=K⋅s+C, where s is the staff intercept.
Optical methods require a clear line of sight between the instrument and the target.
Stadia hairs in the telescope diaphragm allow for distance measurement without physical chaining.
Leveling is the primary application of optical survey instruments for height determination.
High accuracy in terrain where chaining is difficult.
Eliminates physical measurement errors associated with taping over obstacles.
Requires clear visibility and constant atmospheric conditions.
Limited by the maximum magnification of the telescope.
Topographic mapping
Precise leveling for construction projects
Determination of height differences
Chain and tape (Option A) belongs to the category of 'Direct Measurement' or 'Linear Methods'.
E.D.M (Electronic Distance Measurement) (Option C) falls under 'Electronic Methods', which rely on wave propagation (microwaves or light waves) rather than direct optical sighting of staff intervals.
B is correct — The telescope and staff are the primary tools for optical surveying methods used to measure distances and elevations.
Always categorize survey instruments by their working medium: physical (chain/tape), optical (telescope/staff), or electronic (EDM/Total Station).