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Surveying

How to Plot Building Block by the use of Cross Staff?

Object: – Plotting building block by the use of cross staff.

Equipments: –
1. Ranging rod – 3 Nos.
2. 30 m Chain – 1 Nos.
3. Arrow – 5 Nos.
4. Metallic tape (30m) – 1 Nos.
5. Cross staff with stand – 1 Nos.

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Ranging and Fixing Of Survey Station

The object of this experiment is to set up a survey station. This is the basic step of surveying but this is also the one which has the maximum number of errors.

The Equipments used for this are :-

1. Ranging rod …………5 Nos. (min).
2. 30 m Chain…………..1 Nos.
3. Arrow…………………5 Nos. (min.)

The Procedure to conduct is as follow :

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What is Photogrammetry?

Photogrammetry is a technique used in surveying to measure the three dimensional coordinates with the help of photography. It is used for the purpose of measurements.

Fundamental Principle
Triangulation is the fundamental principle used by photogrammetry. In this technique, we take photographs from atleast two different locations. The purpose of taking pictures from more than 2 points is to create what engineers call “lines of sight.” Once these lines of sight are prepared, we join them to locate a point where they meet and thus calculate the coordinates of the desired point.
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Measurement of distance with tapes

Precisions for different methods of measuring distances are given below:-

Pacing (ordinary terrain): 1/50 to 1/100

Taping (ordinary steel tape): 1/1000 to 1/10,000.

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Units of Measurement

Units of measurement used in past and present surveys are

For construction work: feet, inches, fractions of inches (m, mm)
For most surveys: feet, tenths, hundredths, thousandths (m, mm)
For National Geodetic Survey (NGS) control surveys: meters, 0.1, 0.01, 0.001 m
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