As we know that actual shape of the earth is an oblate spheroid. The length of the polar axis is shorter than the equatorial axis, but this difference is very small. So that earth is assumed as a sphere for students understanding. Surveying thus primarily divided into two parts
- Plane Surveying
- Geodetic Surveying
Surveying, in which the surface of the earth is assumed as a plane, and the curvature of the earth is ignored, is known as plane surveying.
It is the type of surveying in which the curvature of the earth is taken into account and a very high standard of accuracy is maintained.
Difference between plane surveying and geodetic surveying are as follows:
Curvature of earth is not taken into account.
Curvature of earth is taken into account.
The line joining any two points is treated as a straight line.
The line joining any two points is treated as the arc of the circle.
Length up to 12KM is treated as plane surveying.
Length more than 12KM is treated as geodetic surveying.
A triangle formed by joining three points is considered as plane triangle and angles formed are considered as trigonometry is required.
A triangle formed by joining three points is considered as spherical angles. Knowledge of spherical trigonometry is required
Knowledge of plane trigonometry is required.
Knowledge of spherical trigonometry is required.
Area up to 196 Sq. Km. is treated as a plane
Area more than 196 Sq. Km. is treated as geodetic surveying.
It is less accurate and less correct.
It is more accurate and more correct.
Used in general civil engineering survey project work
Used for the precise location of a widely distant area.
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