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Surveying or land surveying is the technique, profession, and science of accurately determining the terrestrial or three-dimensional position of points and the distances and angles between them, commonly practiced by surveyors, and members of various engineering professions. These points are usually on the surface of the Earth, and they are often used to establish land maps and boundaries for ownership, locations like building corners or the surface location of subsurface features, or other purposes required by government or civil law, such as property sales.

Surveyors use elements of mathematics (geometry and trigonometry), physics, engineering and the law. Surveying equipment includes total stations, robotic total stations, GPS receivers, prisms, 3D scanners, radios, handheld tablets, digital levels, and surveying software.





Ancient Surveying[edit]

A plumb rule from the book Cassells' Carpentry and Joinery



The Mathmetician Liu Hui described ways of measuring distant objects in his work Haidao suanjing or The Sea Island Mathematical Manual, published in 263AD.


In Medieval Europe, the practice of Beating the bounds was the practice of gathering a group of residents and walking around the boundaries of a parish or village to establish a communal memory of the boundaries. Young boys were included to ensure the memory lasted as long as possible.


Modern surveying[edit]

A plane table was described by Abel Foullon in 1551, but it is thought that the instrument was in use earlier as his description is of a fully developed instrument.

Gunter's chain, introduced in 1620 by English mathematician Edmund Gunter, enabled plots of land to be accurately surveyed and plotted for legal and commercial purposes.

Table of Surveying, 1728 Cyclopaedia



A map by the Great Trigonometrical Survey, produced in 1870


In the USA, the Land Ordinance of 1785 created the Public Lands Survey System, which formed the basis for dividing the western territories into sections to allow the sale of land. States were divided into township grids which were further divided into sections and fractions of sections.


Robert Torrens introduced the Torrens system in South Australia in 1858. Torrens' system was intended to simplify land transactions and provide reliable titles via a centralised register of land. The Torrens system was eventually adopted in several other nations of the English-speaking world.

Because of the fundamental value of land and real estate to the economy, land surveying was one of the first professions to require professional licensure. In many jurisdictions, the land surveyor's license was the first professional licensure issued by the state, province, or government.[citation needed]

20th Century[edit]



The first Satellite positioning system was the U.S. Navy TRANSIT system. The first successful launch took place in 1960. The system's primary purpose was to provide position information to Polaris missile submarines, but it could also be used by surveyors with field receivers to determine the location of a point. The small number of satellites and bulky equipment made observations slow, difficult and inaccurate, so usage of this system was limited to establishing benchmarks in remote locations.


21st Century[edit]

The Theodolite, Total station and RTK GPS survey remain the primary methods in use. Remote Sensing and Satellite imagery continues to improve and become less expensive, allowing more commonplace use. New technologies that have become prominent include 3D scanning and the use of LIDAR for topographical surveys.

Surveying techniques[edit]



Distance measurement[edit]

Historically, distances were measured using a variety of means, such as with chains having links of a known length, for instance a Gunter's chain, or measuring tapes made of steel or invar. To measure horizontal distances, these chains or tapes were pulled taut according to temperature, to reduce sagging and slack. Additionally, attempts to hold the measuring instrument level would be made. In instances of measuring up a slope, the surveyor might have to "break" (break chain) the measurement- use an increment less than the total length of the chain. Perambulators, or measuring wheels could be used to measure longer distances but not to a high level of accuracy. Tacheometry is the science of measuring distances by measuring the angle between two ends of an object with a known size, and was sometimes used prior to the invention of EDM where rough ground made chain measurement impractical.

Angle measurement[edit]


The Plane table provided a graphical method of recording and measuring angles, which reduced the amount of mathematics required.

By observing the bearing from every vertex in a figure, a surveyor can measure around the figure and the final observation will be between the two points first observed, except with a 180° difference. This is known as a close. If the first and last bearings are different, this shows the error in the survey, which is known as the angular misclose. The surveyor can use this information to prove that the work meets the expected standards.


Main article: Levelling


When using an optical level, the endpoint to be leveled may be out of the effective range of the instrument, or there may be obstructions or large changes of elevation between the endpoints. In these situations, multiple setups are needed. Turning is a term used when referring to moving the level to take an elevation shot from a different location. In order to "turn" the level, one must first take a reading and record the elevation of the point the rod is located on. While the rod is being kept in exactly the same location, the level is moved to a new location where the rod is still visible. A reading is taken from the new location of the level and the height difference is used to find the new elevation of the level gun. This may then be repeated until the series of measurements is completed. Because the level must be horizontal to obtain a valid measurement, if the horizontal crosshair of the instrument is lower than the base of the rod, the surveyor will not be able to sight the rod and get a reading. The rod can usually be raised up to 25 feet high, allowing the level to be set much higher than the base of the rod.

Determining Position[edit]


Reference networks[edit]

Main article: Geodetic network
A survey using traverse and offset measurements to record the location of the shoreline shown in blue. Black dashed lines are traverse measurements between reference points (black circles). The red lines are offsets measured at right angles to the traverse lines.


Survey points are usually marked on the earth's surface by objects ranging from small nails driven into the ground to large beacons that can be seen from long distances. The surveyors can set up their instruments on this position and measure to nearby objects. Sometimes a tall, distinctive feature such as a steeple or radio aerial has its position calculated as a reference point that angles can be measured against.



Traversing is a common method of surveying smaller areas. Starting from an old reference mark or known position, the surveyor creates a network of reference marks covering the area to be surveyed and then measures bearings and distances between the reference marks, and to the features to be surveyed. Most traverses form a loop pattern or link between two prior reference marks to allow the surveyor to check their measurements are correct.

Datums and co-ordinate systems[edit]

Many surveys do not calculate positions on the surface of the earth, but instead measure the relative positions of objects. However, often the surveyed items need to be compared to outside data, such as boundary lines or previously surveyed objects. The oldest way of describing a position is via latitude and longitude, and often a height above sea level. However, as the surveying profession grew, attempts were made to create Cartesian coordinate systems that simplified the mathematics for surveys which took place over small portions of the earth. The simplest coordinate systems assume that the earth is flat and measure from an arbitrary point, known as a 'datum'. The co-ordinate system allows easy calculation of the distances and direction between objects, but only over a small area due to the earth's curvature. North is often defined as true north at the datum.

For larger regions, it is necessary to model the shape of the earth using an ellipsoid or a geoid. Many countries have created co-ordinate grids that are customised to minimise error in their area of the earth.

Errors and Accuracy[edit]

A basic tenet of surveying is that no measurement is perfect, and that there will always be a small amount of error.[8] Survey errors are classed into three types:

  • Gross errors or blunders: are errors made by the surveyor during the survey, for example, upsetting the instrument, misaiming a target, or writing down a wrong measurement. A large gross error may reduce the accuracy to an unacceptable level. Therefore surveyors use redundant measurements and independent checks to detect these errors early in the survey.
  • Systematic errors: are errors that follow a consistent pattern. Examples include effects of temperature on a chain or EDM measurement, or a poorly adjusted spirit-level resulting in a misaligned instrument or target pole. Systematic errors that have known effects can be compensated or corrected.
  • Random errors: Random errors are the small unavoidable measurements caused by imperfections in measuring equipment, eyesight, and conditions. They can be minimized by redundancy of measurement and avoiding unstable conditions. Random errors tend to cancel each other out, but checks must be made to ensure they are not propagating from one measurement to the next.

Surveyors avoid propagating errors by ensuring that their equipment is in good condition, using consistent measurement and recording methods, and by good design of their survey reference network. Redundancy of measurements allows the use of averaging and allows outlier measurements to be discarded. Independent checks such as measuring a point from two or more locations or using two different methods means that errors can be detected by comparing the results of the two measurements.

Once the surveyor has calculated the magnitude of the errors in his work, it is adjusted. This is the process of distributing the error between all measurements. Each observation is weighted according to how much of the total error it is likely to have caused and part of that error is allocated to it in a proportional way. The most common methods of adjustment are the Bowditch method and the Principle of least squares method.


Surveying equipment[edit]

A German engineer surveying during the First World War, 1918

The main surveying instruments in use around the world are the theodolite and steel band, the total station, the level and rod and surveying GPS systems. Most instruments are placed on a tripod when in use. Tape measures are often used for measurement of smaller distances. 3D scanners and various forms of aerial imagery are also used.

The Theodolite is an instrument for the measurement of angles. It uses two separate circles, protractors or alidades to measure angles in the horizontal and the vertical plane. A telescope is mounted on trunnions allowing it to be aligned vertically with the target object, while the whole upper section rotates to allow horizontal alignment. The vertical circle measures the angle that the telescope makes against the vertical, known as the vertical angle. The horizontal circle uses an upper and lower plate. When beginning the survey, the instrument is aligned towards a known direction (bearing), and the lower plate is clamped into place. The instrument can then be rotated to measure the bearing to other objects. If no bearing is known or direct angle measurement is desired, the instrument can be set to zero during the initial sight and the readings will then be the angle formed between the initial object, the theodolite itself, and the item that the telescope is aligned with.

The Gyrotheodolite is a form of theodolite that uses a gyroscope to orient itself in the absence of reference marks. It is used mainly in underground applications.



GPS surveying differs from other GPS users in the equipment and methods used. Static GPS uses two receivers placed in position for a considerable length of time. The long span of time allows the receiver to compare a large amount of measurements as the satellites move through the sky, ensuring that the measurement network contains well conditioned geometry. This produces a highly accurate baseline that can be very long. (over 20 km) RTK surveying uses one static antenna that is used to monitor the how satellite movement and atmoshperic conditions are altering the GPS signal and a roving antenna that is used to move from one survey measurement to the next. The two antennas are linked by a radio signal that allows the static antenna to send corrections to the roving antenna. The roving antenna then applies those corrections to the GPS signals it is receiving to calculate its own position. RTK surveying is used over smaller distances than Static methods because the conditions further away from the base station will become too different to allow accurate measurement.

These surveying instruments each have characteristics that make them suitable for certain uses. In first world countries, theodolites and levels are often used by constructors rather than surveyors because they are relatively cheap and let the constructor perform simple survey tasks independently. Total stations are very versatile and will reliably work under all conditions, making them a workhorse for many professional surveyors. The productivity improvements from a GPS, especially on larger scale surveys, makes them popular for major infrastructure or data gathering projects. One-person robotic-guided total stations allow surveyors to gather precise measurements without extra workers to look through and turn the telescope or record data. A fast but expensive way to measure large areas is with a helicopter, equipped with a laser scanner, combined with a GPS to determine the position and elevation of the helicopter. To increase precision, surveyors place beacons on the ground (about 20 km (12 mi) apart). This method reaches precisions between 5–40 cm (depending on flight height).[10]


Types of surveys[edit]


  • Mining surveying: Mining surveying includes directing the digging of mine shafts and galleries and the calculation of volume of rock. It uses specialised techniques due to the restraints to survey geometry such as vertical shafts and narrow passages.

The Surveying profession[edit]

See also: Geomatics
An all-female surveying crew in Idaho, 1918


Whenever there are roads, railways, reservoir, dams, pipeline transports retaining walls, bridges or residential areas to be built, surveyors help determine the placement of structures. They establish the boundaries of legal descriptions and the boundaries of various lines of political divisions. They also provide advice and data for geographical information systems (GIS), computer databases that contain data on land features and boundaries.


Most jurisdictions recognise three different levels of qualification. Survey Assistants or Chainmen are usually unqualified employees who help the surveyor by placing target reflectors, finding old reference marks and marking points on the ground. The term 'chainman' derives from past use on measuring chains, where the assistant would be required to move their end of the chain under the surveyor's direction.

Survey Technicians may be qualified or unqualified and their roles may include operation of survey instruments, running of surveys in the field, survey calculations and drafting of plans. However, a technician typically has no special legal powers and cannot certify their work. Qualifications are typically to the certificate or diploma level.

Licensed, registered or chartered surveyors usually hold a degree or higher qualification and are often required to pass additional exams to gain entrance to a professional association or gain their certification status. Surveyors are responsible for planning and management of surveys and ensuring that their surveys, or surveys performed under their supervision, meet the necessary legal standards. Many principals of surveying firms hold this status.

Informal surveying[edit]

Not all surveys are carried out by professional surveyors. Depending on the jurisdiction and circumstances, the builders of a structure may set it out themselves, or have a surveyor lay out some significant corners of it and then lay out the rest of the building themselves using a variety of techniques.











Legal aspects[edit]



Surveying Institutions[edit]

Most countries regulate at least some forms of surveying via a government survey department that establishes regulations and standards. Standards often deal with accuracy tolerances, who is allowed to call themselves a surveyor, types of monumentation used for boundaries, and maintenance of geodetic networks. Many countries devolve this power to states or regional entities. Cadastral Surveys tend to be the most heavily regulated because of the permanence of the work: lot boundaries established by a cadastral survey can potentially stand for hundreds of years without modification.

Most Jurisdictions also have some form of professional institution representing themselves as a whole. These institutes often have a hand in endorsing or licencing potential surveyors as well as setting and enforcing ethical standards. The largest such institution is International Federation of Surveyors (Abbreviated FIG for French: Fédération Internationale des Géomètres), which represents the survey industry worldwide.

Building surveying[edit]


Cadastral Surveying[edit]

Main article: Cadastral surveying





The art of land surveying[edit]


See also[edit]


  6. ^ Cheves, Marc. "Geodimeter-The First Name in EDM". Retrieved 2014-07-20. 
  7. ^ Mahun, Jerry. "Electronic Distance Measurement". Retrieved 2014-07-20. 
  8. ^ Kahmen, Heribert; Faig, Wolfgang (1988). Surveying. Berlin: de Gruyter. p. 9. ISBN 3-11-008303-5. Retrieved 2014-08-10. 
  10. ^ Toni Schenk, Suyoung Seo, Beata Csatho: Accuracy Study of Airborne Laser Scanning Data with Photogrammetry, p. 118
  13. ^

Further reading[edit]

External links[edit]