Surveying can be defined as the art of determining the relative positions of a point on or below or above the earth surface by undergoing direct or indirect measurements of distance, elevation, and direction. Surveying - Definition, Principle, and Classes

### Significance of Surveying

Both Angular and Linear Measurements are determined in order to establish the points. The main objective of surveying is to prepare a map or plan that represent an area held on a horizontal plane.

• The horizontal projection of an area is represented in the plan and maps
• Vertical distances between the points are shown through contour lines, hachures and other methods in vertical sections.

### Principles of Surveying

The fundamental principles of surveying are:

1. Location of a point by measurement from two points of reference
2. Working from whole to part

### Classes of Surveying

Primarily surveying can be classified into two classes:
1. Plane Surveying
2. Geodetic Surveying

#### Plane Surveying

In this type of surveying, the spheroidal shape of the earth is neglected. It considers the mean surface of the earth as a plane. Triangles that are formed by the survey lines are considered as plane triangles. Level lines are straight and plumb lines are parallel.

#### Geodetic Surveying

In this type of surveying, the shape of the earth is taken into consideration. Lines laying on the earth surface are curved lines and the respective triangles formed are spherical triangles. Hence, this surveying take into consideration, the spherical trigonometry.