A backsight (BS) is a sight taken with the level to a point X of known elevation E(X) , so that the height of the instrument HI can be found. A backsight in direct levelling is usually taken in a backward direction, but not always.

What is backsight in levelling?

A backsight (BS) is a sight taken with the level to a point X of known elevation E(X) , so that the height of the instrument HI can be found. A backsight in direct levelling is usually taken in a backward direction, but not always.

What is the precise leveling?

Precise levelling is a time-consuming measuring method, which has many repetitive work stages. Basically, the work stages are simple and thus they could be done by robots. The central idea of the proposed method is that robots move and control levelling instruments and rods.

How do you set auto level?

Auto Level Setup

  1. Setup your tripod as level as possible, step on tripod legs to drive into the ground.
  2. Attach auto level to the tripod.
  3. Adjust level so bubble is centred in vial.
  4. Adjust recital until cross-hairs are clear.
  5. Adjust the objective lens until object you are sighting on is clear.

What is backsight and foresight reading in levelling?

The backsight is the first staff reading taken after the level is set up and leveled at the point. Foresight (FS) or Foresight reading. It is a staff reading taken on a point whose elevation has to be determined through levelling process. It is also known as minus sight.

What is Backsight method?

[′bak‚sīt ′meth·əd] (engineering) A plane-table traversing method in which the table orientation produces the alignment of the alidade on an established map line, the table being rotated until the line of sight is coincident with the corresponding ground line.

What is a backsight in surveying?

Definition of 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 purpose of backsight?

backsight-1 A point used to determine the elevation and/or angular orientation of the surveying instrument.

Which method of levelling is most accurate?

Differential leveling is the most accurate of the three methods. With the instrument locked in position, readings are made on two calibrated staffs held in an upright position ahead of and behind the instrument. The difference between readings is the difference in elevation between the points.

Which auto level is best?

1. Topcon 32X Automatic Level AT-B2. When you’re looking for a transit level for sale, you can’t go wrong with the Topcon 32X Automatic Level AT-B2. This level measures heights, angles, and distances, and you can also use it to determine if a structure is level.

How do you center bubbles in auto level?

Rotate the telescope through 90° so the bubble tube is aligned with the third levelling screw.

  1. The first two screws are level so they must not be touched.
  2. Using the left hand adjust the third levelling screw to centre the bubble. Again the bubble will move in the same direction as the left thumb.

Why backsight and the foresight distance should be equal in leveling?

In a level circuit with no inverted rod shots, backsight readings are added and foresights are subtracted. Therefore, if the backsight and foresight distances are equal, each backsight error will be canceled by the following foresight error.

How do I take a backsight reading with the leveling instrument?

Procedure: Set up the leveling instrument at Level position 1. Hold the staff on the Datum (RL+50 m) and take a reading. This will be a backsight, because it is the first staff reading after the leveling instrument has been set up. Move the staff to Aand take a reading.

What is the difference between backsight and foresight?

The backsight is the first staff reading taken after the level is set up and leveled at the point. Foresight (FS) or Foresight reading It is a staff reading taken on a point whose elevation has to be determined through levelling process. It is also known as minus sight.

How do I set up a backsight sight?

Hold the staff on the Datum (RL+50 m) and take a reading. This will be a backsight, because it is the first staff reading after the leveling instrument has been set up. Move the staff to Aand take a reading. This will be an intermediate sight. Move the staff to Band take a reading.

How do I use the leveling instrument?

Figure 1 Procedure: Set up the leveling instrument at Level position 1. Hold the staff on the Datum (RL+50 m) and take a reading. This will be a backsight, because it is the first staff reading after the leveling instrument has been set up. Move the staff to Aand take a reading.