**Surveying is divided into two main categories:-**

- Geodetic Survey
- Plane survey

**1) Geodetic Survey:-** When survey extends over a large areas more than 200 sq. km. and degree of accuracy is also great.** The curvature of earth is also taken into account.** Geodetic survey is used to provide control points to which small surveys can be connected.

**2) Plane Survey:-** For small projects covering Area less than 200 sq.km.** Earth curvature is not counted for in distances.** Earth surface is considered as plane. (Angular error of 1” in 200 sq. km. area by assuming plane).

**Classification based upon equipment used :**

Based on various types of instruments used, surveying can be classified into six types.

- Chain survey
- Compass survey
- Theodolite survey
- Plane Table survey
- Tacheometric survey
- Aerial Photographic Survey
- Remote sensing.

#### Classification based on object:

Based on object, surveying can be classified into:

- Geological Surveying
- Mine Surveying
- Archaeological surveying
- Military surveying

**Classification Based upon Method Employed :**

Based on methods adopted, surveying can be classified into:

**1) Triangulation:** The tracing and measurement of a series or network of triangles in order to determine the distances and relative positions of points spread over an area, especially by measuring the length of one side of each triangle and deducing its angles and the length of the other two sides by observation from this baseline.

**2) Traversing:** The length and direction of any survey line can be measured with any direction measuring instrument such as compass,theodolite and for measuring length chain or tape can be used.

**3) Trilateration:** In which the lengths of the sides of a triangle are measured, usually by electronic means, and, from this information, angles are computed. By constructing a series of triangles adjacent to one another, a surveyor can obtain other distances and angles that would not otherwise be measurable.

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