## Plane Tabling
Definition (1 mark)
Plane tabling is a graphical method of surveying in which field observations and plotting are carried out simultaneously on a drawing sheet fixed to a plane table.
Methods of Plane Tabling (2.5–3 marks)
The main methods of plane tabling are:
1. Radiation Method
- The table is set up at one station.
- Lines are drawn from the station to different points.
- Distances are measured and plotted to scale.
2. Intersection Method
- Two stations are selected and plotted.
- Rays are drawn from both stations to locate the object.
- The intersection of rays gives the position.
3. Traversing Method
- The table is shifted from one station to another.
- Distances and directions are measured.
- Points are plotted successively.
4. Resection Method
- Used to locate the position of the table station.
- Known plotted points are sighted to determine the station.
- Includes two-point and three-point problems.
Merits of Plane Tabling (2–3 marks)
- Observation and plotting are done simultaneously → saves time
- No need for field book → reduces errors
- Errors can be detected and corrected on the spot
- Simple and easy equipment
- Suitable for small-scale and detail surveys
Demerits of Plane Tabling (2–3 marks)
- Not suitable for high accuracy work
- Cannot be used in rainy or windy weather
- Requires clear visibility of points
- Equipment is bulky and difficult to carry
- Not suitable for large areas
Conclusion (1 mark)
Plane tabling is a simple and rapid surveying method where measurement and plotting are done together, making it suitable for small-scale mapping, though it is less accurate compared to modern instruments.
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