Generally, surveys can be classified by names descriptive of their functions. There are seven main branches of land surveying, although these separation tend to overlap to varying degrees. The branches includes:
1. Geodetic Survey
2. Topographical Survey
3. Cadastral Survey
4. Engineering Survey
5. Hydrographic Survey
6. Remote Sensing
7. Photogrammetry
1. Geodetic Surveys
These are generally surveys carried out on a National basis or level which provide survey stations precisely located, large distance apart. Account is taken of the curvature of the science of geodesy in which the size and shape of the earth are examined.
Divisions Of Geodetic Surveying
Geodetic surveying can be divided in the following ways:
1. Triangulation: In this type of surveying, a network of well-defined triangles are formed on the plot of land to be surveyed. Only one line known as base line and all other angles are measured very carefully.
2. Reciprocal Leveling: This type of surveying is required to obtain the difference in levels between two points which are separated by obstacles.
3. Stadia or Techeometric Surveying: This is a type of surveying in which vertical and horizontal distances are computed from stadia readings without using chain or tape.
4. Astronomical Surveying: It is a branch of surveying in which the meridian, azimuth, latitude, time etc of a place on the surface of the earth are determined by observation of some bodies like the sun and the fixed stars.
5. Photographic Surveying: This is a method of surveying in which plans or maps are prepared from photographs taken from suitable camera stations.
2. Topographical Surveys
These are surveys where the physical features of the earth are measured and maps and plans prepared to show their relative position both horizontally and vertically. Depending on the extent under survey these consist of either; geodetic type of surveys or plane surveys where no account is take of the curvature of the curvature of the earth.
3. Cadastral Surveys
These are surveys undertaken to defined and record the boundaries of properties, legislative areas and even countries. In some cases cadastral surveys may be almost entirely topographic where features define boundaries.
In others accurately surveyed beacons or markers define boundary corner or line points and little account may be taken of the topographer features.
4. Engineering Or Construction Surveys
These are surveys undertaken to provide special information projects. They are essentially large – for construct they are essentially large _ scale topographies details for particular engineering scheme and could include the setting out of works on the ground.
These are usually plane surveys, but on large projects such as motor ways and pipe lines some geodetic control may be necessary.
They are conducted to obtain data essential for planning, estimating, locating, and layout for the various phases of construction activities or projects. This type of survey includes reconnaissance, preliminary, location, and layout surveys.
Engineering and/or construction surveys, then, form part of a series of activities leading to the construction of a man-made structure. The term structure is usually confined to something that is built of structural members, such as a building or a bridge.
It is used here in a broader sense, however, to include all man-made features, such as graded areas; sewer, power, and water lines; roads and highways, and waterfront structures. Constructions surveys normally cover areas considered small enough to use the plane surveying methods and techniques.
5. Hydrographic Surveying
We also have hydrographic surveying as distinct from land surveying. Hydrographic (sea) surveying is defined as the science of measuring and depicting those parameters that are necessary to describe the precise nature and configuration of the river and sea beds, its geographical relationship to the Landmass and the characteristics abd dynamics of rivers and seas.
6. Remote Sensing
This is the science and art of obtaining information about an object, area or phenomenon through the analysis, interpretation, classification and identification of data acquired by a device that is not in contact with the object, area of phenomenon under investigation. The data are remotely collected by sensors.
These sensors measure and record the variation in the electromagnetic energy emitted or reflected by various features on the earth surface. They are usually operated from an airborne platforms. The data collected may be of any form – variation in force distribution, acoustic wave distribution or electromagnetic energy distribution.
7. Photogrammetric Surveying
In view of these developments, photogrammetry is now defined as the science, art and technology of obtaining reliable information about physical objects and the environment through processes of recording, measuring and interpreting photographic images and recorded electromagnetic energy patterns and other phenomena.
Photogrammetrists analyze aerial and terrestrial photographs to obtain information about physical objects and the environment.