What is FS in surveying?

Fore sight (FS) – short for «fore sight reading», the last staff reading taken before changing the instrument to the other position. It is the staff reading taken on point whose RL is to determined. This sight is considered as negative and deduced from Height of Instrument to determine RL of the point.

What is BS and FS in surveying?

From each levelling station, measure a backsight (BS) and a foresight (FS) , except: at starting point A, where you have only a backsight measurement. at ending point B, where you have only a foresight measurement.

What is the purpose of equalizing BS and FS distances?

The balancing of the FS and BS distances is important in leveling. The effeet of curvature and refraction may be eliminated by a balanced BS and FS distance; however, instrumental error is a far more important reason for careful balancing.

What is foresight and backsight?

h) Back sight : (B.S.) — The first sight taken on a levelling staff held at a point of known elevation. B.S. enables the surveyor to obtain HI +sight i.e. Height of Instrument or line of sight. i) Fore Sight : (F.S.) – It is the last staff reading taken from a setting of the level. It is also termed as minus sight.

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What is a survey level?

Surveyor’s level, instrument used in surveying to measure the height of distant points in relation to a bench mark (a point for which the height above sea level is accurately known). It consists of a telescope fitted with a spirit level and, generally, mounted on a tripod.

What is HI method?

Height of instrument method deals with obtaining the RL of the line of collimation by adding BS reading of a point whose RL is known. The RL of line of collimation is called Height of Instrument. From this, the staff readings of all intermediate stations is subtracted to get the RL at those points.

What is foresight reading?

A foresight is a reading taken on a position of unknown coordinate(s). Since a survey progresses from a point of known position to points of unknown position, a foresight is a reading looking «forward» along the line of progress.

What is foresight in Levelling?

Fore sight (FS) – short for «fore sight reading», the last staff reading taken before changing the instrument to the other position. It is the staff reading taken on point whose RL is to determined. This sight is considered as negative and deduced from Height of Instrument to determine RL of the point.

What is collimation error?

i. Collimation error is due to the line of sight of a survey instrument not coinciding with traversing gear, scales, or leveling devices. … The collimation line is the line of sight, passing through the intersection of the crosshairs of the reticule.

Why is it necessary in balancing backsight and foresight distance?

Explanation: If the back sight and foresight distances are balanced, the difference in elevation between two points can be directly calculated by taking a difference of two readings and no correction for the inclination of the line of sight is necessary.

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What is a backsight?

1 surveying : a reading of the leveling rod in its unchanged position when the leveling instrument has been taken to a new position. 2 surveying : a sight directed backward to a previous station.

What is the difference between backsight and foresight?

As nouns the difference between backsight and foresight

is that backsight is the rear sight of a firearm while foresight is the ability to foresee or prepare wisely for the future.

How do you calculate RL in surveying?

The difference between the sum of the back sights and the sum of the fore sights should be equal to the difference of the first and the last R.Ls i.e. Σ B.S. – Σ F.S. = Last R.L. -First R.L. This check verifies the calculation of R.Ls. of the planes of collimation and of the change points only.

What are the types of surveying?

Based on various types of instruments used, surveying can be classified into six types.

  • Chain surveying.
  • Compass surveying.
  • Plane table surveying.
  • Theodolite surveying.
  • Tacheometric surveying.
  • Photographic surveying.

24 дек. 2016 г.

What is meant by surveying?

Surveying or land surveying is the technique, profession, art, and science of determining the terrestrial or three-dimensional positions of points and the distances and angles between them. A land surveying professional is called a land surveyor.

What are the instruments used in surveying?

List of surveying instruments

  • Alidade.
  • Alidade table.
  • Cosmolabe.
  • Dioptra.
  • Dumpy level.
  • Engineer’s chain.
  • Geodimeter.
  • Graphometer.