Surveying is generally described as methodology of making scientific measurements on or above the surface of earth with the objective of determining points so as to produce a plan or map. Surveying is used widely in almost all civil engineering projects such as construction of building, bridges, reservoirs, dams, railways, roads, irrigation projects etc.
Primarily, surveying can be divided into two categories:
- Plane Surveying
- Geodetic Surveying
What Is Plane Surveying?
Plane surveys are the most commonly practiced method of surveying and treat the earth as a flat or ‘’plane’’ surface. This type of survey is used when the size of the area to be surveyed is small (less than 260 square kilometers). This survey never taken into consideration the curvature of the earth and thus the computation and results can be referenced to a plane or flat surface. This most commonly practiced type of survey as it is economical in nature.
In order undertake calculations in this type of survey, triangles are formed on the ground and these triangles are assumed to be plane triangles and in this regard the rules of plane triangles are used in computation. Usually, the error associated with the result of computation is directly proportional the size of the area to be surveyed. That is to say, the bigger the area the bigger the error margin. Plane surveys are used in surveying of location and construction of roads, highways, cannel and landing fields.
Plane Surveying Diagram
What You Need To Know About Plane Surveying
- Plane surveying is a type of surveying in which the mean surface of the earth is considered to be plane i.e two dimensional.
- The lines formed by joining any two points are considered as a straight line-as the same angles are plain angles).
- In plane surveying, the effect of the spherical nature of the earth’s surface is never taken into account.
- This type of surveying involves smaller areas less than about 260Km^{2.}
- Plane surveying has a lower degree of accuracy.
- Plane surveying uses normal instruments like a chain, measuring tape, theodolite etc.
- It is done locally by the individual organization and firms.
- It is used in general civil engineering survey project work.
- In this type of surveying, knowledge of plane trigonometry is necessary.
- It is the most economical and easy type of surveying.
- The triangle formed by any three points is considered as plain.
What Is Geodetic Surveying?
Geodetic surveying also referred to as Trigonometric surveying is a type of surveying that takes into consideration the curvature of the earth when taking measurements on earth’s surface. Geodetic surveys are typically carried out with great precision, often over long distances and are used to determine the size, shape and gravity field of the earth.
The main objective of geodetic survey is to determine the precise position on the surface of the earth, of a system of widely distant points which form control stations to which surveys of less precision may be referred. In other words, Geodetic survey is used to provide control points to which small surveys can be referred.
In this type of survey, all lines lying on the surface are curved lines and the triangles formed are Spherical triangles. Measurements are taken using high precision instruments whereas calculations are done using spherical trigonometry method. The position of each geodetic station is expressed using longitude and latitude and; Global Positioning System (GPS) is usually used in this regard.
Geodetic Surveying Diagram
What You Need To Know About Geodetic Surveying
- Geodetic surveying is a type of surveying in which the mean surface of earth is assumed to be spherical i.e three dimensional.
- The lines formed by joining any two points are considered as arch-as the same angles are spherical angles.
- In geodetic surveying, the effect of spherical nature of earth’s surface is taken into account.
- This type of surveying involves larger areas more than about 260 Km^{2}.
- Plane surveying has a higher degree of accuracy.
- Geodetic surveying uses more precise instruments and modern technology like GPS.
- It is done by governments and state departments.
- They are used for the precise location of a widely distant area.
- In this type of surveying, knowledge of spherical trigonometry is necessary.
- It is the most costly and complex type of surveying.
- The triangle formed by any three points is considered as spherical.
Also Read: Difference Between Orthographic And Oblique Projection
Difference Between Plane Surveying And Geodetic Surveying In Tabular Form
BASIS OF COMPARISON | PLANE SURVEYING | GEODETIC SURVEYING |
Description | Plane surveying is a type of surveying in which the mean surface of the earth is considered to be plane i.e two dimensional. | Geodetic surveying is a type of surveying in which the mean surface of earth is assumed to be spherical i.e three dimensional. |
The Lines Formed By Joining Any Two Points | The lines formed by joining any two points are considered as a straight line-as the same angles are plain angles). | The lines formed by joining any two points are considered as arch-as the same angles are spherical angles. |
Spherical Nature Of The Earth’s Surface | The effect of the spherical nature of the earth’s surface is never taken into account. | The effect of spherical nature of earth’s surface is taken into account. |
Area Involved | This type of surveying involves smaller areas less than about 260Km^{2 } | This type of surveying involves larger areas more than about 260 Km^{2}. |
Accuracy | It has a lower degree of accuracy. | It has a higher degree of accuracy. |
Instruments | It uses normal instruments like a chain, measuring tape, theodolite etc. | It uses more precise instruments and modern technology like GPS. |
Nature | It is done locally by the individual organization and firms. | It is done by governments and state departments. |
Application | It is used in general civil engineering survey project work. | They are used for the precise location of a widely distant area. |
Required Concept | In this type of surveying, knowledge of plane trigonometry is necessary. | In this type of surveying, knowledge of spherical trigonometry is necessary. |
Cost | It is the most economical and easy type of surveying. | It is the most costly and complex type of surveying. |
Triangles | The triangle formed by any three points is considered as plain. | The triangle formed by any three points is considered as spherical. |
Also Read: Difference Between First And Third Angle Projection