The work of the land surveyor can be classified into three main areas of responsibility.
- Firstly, he is concerned with the recording of measurements which allow the size and shape of the Earth to be determined.
- Secondly, and primarily, he is involved in the collection, processing and presentation of the information necessary to produce maps and plans.
- Thirdly, he may be required to locate on the surface of the Earth the exact positions to be taken up by new roads, dams or other civil engineering works.
As a consequence of the diverse nature of the land surveyor’s duties, several distinct branches of the subject have evolved.
Branches of surveying
- Geodetic surveys are carried out on a national or international basis in order to locate points large distances apart. This type of survey acts as a framework for ‘lower order’ surveys. In order to ensure high accuracy, the effect of factors such as the curvature of the Earth on observations must be considered and the necessary corrections applied.
- Topographic surveys are concerned with the small-scale representation of the physical features of the Earth’s surface. Frequently, the data necessary for such an operation will be provided by the use of aerial photography. The science of taking measurements from photography in order to produce maps is known as photogrammetry. Topographic surveys are often the responsibility of a national organization. such as, for example, the Ordnance Survey in the UK, Survey of India in India.
- Hydrographic surveys, in contrast, involve the representation of the surface of the seabed. The end-product is normally a navigational chart. In recent years this branch has become increasingly important with the development of the offshore oil industry. In this case, in addition to the production of charts, the surveyor may be required to position large structures such as oil production platforms. This type of operation would normally necessitate the use of ground and satellite electronic position-fixing equipment.
- Cadastral surveys relate to the location and fixing of land boundaries. In many countries in the world, e.g. Australia, India, the information supplied by the cadastral surveyor may be an integral part of a land registration system.
- Finally, engineering surveys are required for the preparation of design drawings relating to civil engineering works such as roads, dams or airports. The surveys are normally at a large scale, with scales of 1:500 and 1:1000 being most common.
Many of these branches require highly specialized knowledge.