Surveying is classified first by whether the earth’s curvature is considered: plane surveying (curvature ignored, areas up to about 250-260 km²) and geodetic surveying (curvature accounted for, larger areas). Surveys are then classified by their object or purpose (land, topographic, cadastral, engineering, route, hydrographic, mine, astronomical), by the instrument used (chain, compass, plane table, theodolite, tacheometer, total station, GNSS, photogrammetry, drone and LiDAR) and by the method of fixing points (triangulation, trilateration and traversing).
This page is only about how surveys are grouped. Each technique is taught in detail in the surveying section, and the links below point to the right chapter for each class.
Primary classification of surveying: plane vs geodetic
Plane surveying
In plane surveying the earth’s surface is treated as flat. A level line is taken as a straight line, plumb lines at different points are taken as parallel, and the angles of a triangle add up to 180°. This is acceptable for small areas, and the usual textbook limit is about 250-260 km² (100 square miles). Almost all civil engineering work (building sites, roads, canals, township layouts) is plane surveying.
Why the limit is safe: the spherical excess of a triangle on the earth is its area divided by R². For an area of about 196 km² and R = 6,371 km, that is 196 / 6,371² = 4.8 × 10−6 radians, or about 1 second of arc, which is below what an ordinary theodolite reads. The difference between an 18 km arc on the earth and its chord works out to only about 6 mm.
Geodetic surveying
Geodetic surveying treats the earth as a spheroid (in practice an ellipsoid such as WGS 84). Lines are curved, and triangles are spherical, with angles adding up to more than 180°. It is used over large areas and to set up the national network of accurately located control points that plane surveys then hang from. In India this is the work of the Survey of India, whose Great Trigonometrical Survey of the 19th century was a geodetic survey.
| Point | Plane surveying | Geodetic surveying |
|---|---|---|
| Earth’s shape | Flat | Spheroid / ellipsoid |
| Area | Up to about 250-260 km² | Larger areas, whole states or countries |
| Triangle angles | Sum = 180° | Sum = 180° + spherical excess |
| Accuracy needed | Ordinary | Very high |
| Typical agency | Engineers, contractors, local surveyors | National mapping agencies (Survey of India) |
Classification by object or purpose
Land survey
Fixes boundaries and areas of properties, and relocates old boundaries. It includes the cadastral survey below and the setting out of plots.
Topographic survey
Records natural and man-made features (hills, rivers, roads, buildings) together with ground heights, usually shown as contours. Heights come from levelling and contouring.
Cadastral survey
Fixes property boundaries for ownership, taxation and land records. In India, village maps and land records under state revenue departments come from cadastral surveys.
Engineering survey
Collects the data needed to design and build a project: site plans, quantities of earthwork, setting out foundations, and checking construction. It is done in three stages: reconnaissance, preliminary and location (setting out).
Route survey
An engineering survey for long, narrow works such as roads, railways, canals and pipelines. It includes longitudinal sections, cross-sections and the setting out of curves.
Hydrographic survey
Maps water bodies: depths (soundings), shorelines, tides and currents, for navigation, ports, dams and dredging. See the hydrographic survey article for the history of the field.
Mine survey
Fixes the position of underground workings relative to the surface, so that tunnels and shafts are driven in the right direction and property limits are respected.
Astronomical survey
Determines absolute latitude, longitude, azimuth and time from observations of the sun and stars. It gave the reference directions for older surveys; GNSS has largely replaced it.
Other purpose-based types you will see in syllabi include geological, archaeological and military surveys.
Classification by instrument
Chain survey
Only linear measurements are taken, with a chain or tape, and the area is divided into triangles. It suits small, fairly open and level areas. Covered in chain and compass surveying.
Compass survey
Directions of survey lines are measured as bearings with a prismatic or surveyor’s compass, and lengths with a chain or tape. It is quick but affected by local magnetic attraction.
Plane table survey
A graphical method in which the map is plotted in the field on a drawing board while observations are made, so nothing is missed. Suited to small-scale mapping and filling in detail.
Theodolite survey
Horizontal and vertical angles are measured with a theodolite, usually to 20″ or better. It is the basis of traversing and triangulation.
Tacheometric survey
Horizontal distances and heights are obtained optically from staff readings through a tacheometer, without chaining. Useful in rough or hilly ground. Plane table and tacheometry are covered together in tacheometry and plane table surveying.
Total station survey
A total station combines an electronic theodolite with electronic distance measurement (EDM) and records coordinates directly. It is the standard instrument on Indian construction sites today.
GPS / GNSS survey
Positions are found from satellite signals (GPS, GLONASS, Galileo, and India’s NavIC). RTK receivers give centimetre-level positions in real time. See total station and GPS.
Photogrammetric survey
Measurements are taken from overlapping photographs, either from aircraft (aerial) or from the ground (terrestrial). It suits large or inaccessible areas.
Drone and LiDAR survey
Drones carry cameras for photogrammetry or LiDAR scanners that measure millions of points with laser pulses, producing orthophotos and 3D terrain models. The SVAMITVA scheme uses drone surveys to map rural inhabited land in India.
Levelling is sometimes listed here too, as a survey done with a level and staff to find heights.
Classification by method
Triangulation
A network of triangles is formed; one or more baselines are measured accurately and the rest of the network is computed from measured angles. It was the classic method for large control surveys. When all sides are measured by EDM instead of angles, the method is called trilateration.
Traversing
A series of connected lines whose lengths and directions are measured. A closed traverse returns to its start or ends on a known point, so its error can be checked and adjusted. Both methods are explained in theodolite and traversing, and the working formulas are collected in surveying formulas.
Summary table: classification of surveying
| Basis of classification | Types |
|---|---|
| Earth’s curvature (primary) | Plane surveying, geodetic surveying |
| Object or purpose | Land, topographic, cadastral, engineering, route, hydrographic, mine, astronomical (also geological, archaeological, military) |
| Instrument | Chain, compass, plane table, theodolite, tacheometric, total station, GPS/GNSS, photogrammetric, drone/LiDAR (also levelling) |
| Method | Triangulation, trilateration, traversing |
| Nature of field | Land surveying, marine (hydrographic) surveying, astronomical surveying |
Exam tip: when a question asks for “primary” and “secondary” classification, the primary is plane vs geodetic and the secondary is every other basis listed above.
FAQs
What is the primary classification of surveying?
Plane surveying and geodetic surveying. Plane surveying ignores the earth’s curvature and is used for areas up to about 250-260 km²; geodetic surveying accounts for curvature over larger areas.
What are the types of surveying based on instruments?
Chain, compass, plane table, theodolite, tacheometric, total station, GPS/GNSS, photogrammetric and drone/LiDAR surveys. Levelling with a level and staff is often included as well.
What is the difference between cadastral and topographic surveys?
A cadastral survey fixes property boundaries for ownership and land records. A topographic survey records the ground’s features and heights, usually as a contour map.
Which type of survey is used for roads and railways?
A route survey, which is a kind of engineering survey. It covers the alignment, longitudinal and cross-sections, and setting out of curves.