# Geoinformatics and Surveying Definition and Classification

Geoinformatics and surveying though are not same but highly interrelated. Surveying is the process of collecting the Geoinformation in Geoinformatics. Surveying from the Civil Engineering point of view is of major importance no matter how small or large the project is, we use surveying and Geoinformatics science for understanding the topography of land and area , feasibility study in planning and to have a representative animated or pictorial view of the land area under concern within our desk what we call a map.

It may be noted that Geinformatics and surveying are not only restricted to land of earth it also covers the water area like in marine surveying, and the outer space like in the Astronomical Surveying

# Definition of Geoinformatics

Geoinformatics is the science of collecting geoinformations (height, size, shape, location etc.) of land area which may be ranging from small to very large (can be whole planet also) including objects and topography therein and manipulating those geoinformations and store in presentable understandable format, and applying those data so stored for future reference.

# Definition of Surveying

Surveying is the art of determining relative location and physical characteristics of various objects on or below the surface of the earth with the objective of preparing map.

Electronic Total Station

# Types or Primary Classification of surveying

Surveying are of mainly two types as follows

## Plain Surveying:

The surveying in which we consider the earth surface to be flat, not curved and we neglect the fact that the earth surface is actually curved surface is called as the Plain Surveying. Plain surveying is done in smaller size of area of land like up to 250 sq.km (It is tiny if we consider the whole earth surface). Actually, if we do survey in small area coverage then the difference of the curved surface of the earth and the horizontal flat surface is very small that can be neglected. The Earth is having a diameter of 12,734.889 km approximately, therefore, the rate of change of curvature (deviation of the curved surface from the horizontal surface) is very less with respect to the practical lengths of the small area survey say 20kmx25km along the surface of the Earth. For each 20km of distance traveled on the surface of the earth only about 10mm is deviated from the horizontal surface, which is quite negligible for such a distance. Due to the above fact in small area surveying the surface of the Earth is considered to be flat and horizontal, and the surveys which are carried out in such a small area are known as Plain Surveying.

Effects of Earth’s Curvature in Leveling

## Geodetic Surveying:

The surveying in which we consider the earth surface to be curved, not flat and we take the fact into account that the Earth surface is actually curved surface is called as the Geodetic Surveying. Geodetic surveying is done in larger size of area of like over 250 sq.km. While surveying in large area the curvature of the Earth plays a significant role specially in case of determining relative heights of different objects and their relative elevation. In this type of survey, we have to consider the difference of level incurred between the horizontal plane and the actual curved plane of the Earth surface for calculations as it is eminent that, due to curvature of the Earth two objects at large distance apart will not have their base on the Earth surface at the same horizontal plane, instead one object with respect to the other will always appear to be shortened in height or elevation, as shown in the above image of Effects of Earth’s Curvature in Leveling in case of Two Towers of same height ‘x’ at a considerable distance apart. Here, due to the effect of the Eearth’s curvature one tower will always appear to be shorter with respect to the other. Due to the above fact while we carry out surveys in larger area we consider and calculate taking into account the difference of levels emerged due to curvature of the Earth and such surveys are known as the Geodetic Surveying.

# Secondary or Detailed Classification of Surveying

Survey can be classified into various distinguished heads, some of them are as mentioned below.

1. Based on Instruments

• Chain Surveying
• Compass Surveying
• Plane Table Surveying
• Theodolite Surveying and
• Tacheometric Surveying
• Photographic Surveying (in Ariel Surveying)
• Total Station Surveying and Electronic Total Station Surveying
• GPS Surveying
• Satellite Remote Sensing

2. Based on Methods

• Triangulation Surveying
• Traverse Surveying

3. Based on Object of Surveying

• Geological Surveying
• Mine Surveying
• Archaeological Surveying
• Military Surveying

4. Based on Nature of Field

• Land Surveying
1. Topographical Surveying