Plane surveying is a specific type of surveying where the surface of the earth is considered as plane and the curvature of the earth is not taken into account. The line connecting any two points is a straight line and the angles of polygons are plane angles. Plane surveying is suitable for small and flat areas and its degree of accuracy is comparatively low. In America, the limit for treating a surface as a plane is about to 250 km2.
Note: The difference in length between the arc and the subtended chord on the surface of the earth is only about 0.1 m in 18.2 km, 0.3 m in 54.3 km and 0.5 m in 91 km respectively.
1. Chain Surveying:
Chain surveying is the simplest method of surveying in which the linear measurements are directly taken in the field and the angular measurements are not taken. This type of surveying is mostly suitable when,
1. The area is small.
2. The ground is fairly level and open.
3. Plans on a large scale are required.
2. Plane Table Surveying:
In plane table surveying the field work and plotting is done using a graphical method. It is mostly adapted for small and medium scale mapping where great accuracy is not required.
3. Compass surveying:
In this surveying, a compass is used to determine the direction of survey lines, and the length of survey lines are measured by a chain or tape.
4. Theodolite Surveying:
In this surveying, a theodolite (a surveying instrument) is used to measure the horizontal and vertical angles.
Leveling is a method of surveying which determines the heights or elevations of relative points on the surface of the earth.