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Compare Direct and Indirect Contouring Methods

The Comparison of Direct and Indirect Contouring Methods is shown below in tabular form
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How to determine Area of Field using Cross Staff Survey?

Object: – To determine area of field using cross staff survey.

Equipments:
1. Ranging rod – 7 Nos.
2. 30 m Chain – 1 Nos.
3. Arrow – 5 Nos.
4. Metallic tape (30m) – 1 Nos.
5. Cross staff with stand – 1 Nos.

Procedure: –
1. Field work
2. Classroom work

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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 :

(Ranging by eye)
1. First of all first ranging rod is established at known point A and its ranging rod should be fixed at point A up to completion of work.

2. Second ranging rod is established at known point B (or at known object) and a ranging rod should be fixed at point B up to completion of work.

3. Third ranging rod established at point P (or any) approximately on the line of point AB (by judgment) and it’s not greater than one chain length from point A.

4. Measure the distance of AP by chain and move ranging rod at point P to its next position and establishing a wooden peg or arrow at point P.

5. Third ranging is established at point Q (or any) approximately on the line of point AB (by judgment) and it’s not greater than one chain length from point P.

6. Measure the distance of PQ by chain and move ranging rod at point Q to its next position and establishing a wooden peg or arrow at point Q.

7. Its procedure repeats up to reaching point B.

8. Third ranging rod is established at known point C (or at known object) and a ranging rod should be fixed at point C up to completion of work.

9. Fourth ranging rod established at point P’ (or any) approximately on the line of point BC (by judgment) and it’s not greater than one chain length from point B.

10. Measure the distance of BP’ by chain and move ranging rod at point P’ to its next position and establishing a wooden peg or arrow at point P’.

11. Fourth ranging is established at point Q’ (or any) approximately on the line of point BC (by judgment) and it’s not greater than one chain length from point P’.

12. Measure the distance of P’Q’ by chain and move ranging rod at point Q’ to its next position and establishing a wooden peg or arrow at point Q’.

13. Its procedure repeats up to reaching point C.

14. Fifth ranging rod established at point P” (or any) approximately on the line of point CA (by judgment) and it’s not greater than one chain length from point C.

15. Measure the distance of CP” by chain and move ranging rod at point P” to its next position and establishing a wooden peg or arrow at point P”.

16. Fifth ranging is established at point Q” (or any) approximately on the line of point CA (by judgment) and it’s not greater than one chain length from point P”.

17. Measure the distance of P”Q” by chain and move ranging rod at point Q” to its next position and establishing a wooden peg or arrow at point Q”.

18. Its procedure repeats up to reaching point A.

19. Finally complete a triangle and position of point A, B, and C is known respect to each other.

observation-table

figure-surverying

Precautions: –
1. The ranging rod should be established correctly state at all points.
2. The judgment of line should be taking correctly during established ranging rod at a point.
3. Distance between surveyor’s eye and reference station (eg. A, B and C) should be minimum one meter.

We are thankful to Mr Praveen Kumar Pandey for this very useful article and we hope to see more such contributions.

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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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