Guide to GPS, GIS and Land Surveying

Land Surveying - Past, Present and Future

Land surveying is a means of making relatively large-scale, accurate measurements of the earth surfaces. Land surveyors determine the form, extent, and position of a tract of land by taking linear and angular measurements by applying the principles of geometry and trigonometry.

Origin of Land Surveying

Land surveying can be traced back to ancient Egypt when the Great Pyramid of Khufu at Giza was built in 2700 BC.

Surveys can be either plane surveys or geodetic surveys. Plane surveys do not take in consideration the curved shape of the earth's surface. They are used for land area that is within 10km by 10km. For the larger areas of land, geodetic surveys make adjustments for the earth curvature.

Land surveying is an essential element in the development of the human environment. It is required in the planning and execution of nearly every form of construction.

Land Surveying Concepts

Land surveyors must not only apply the principles of geometry and trigonometry, but also have a thorough knowledge of algebra, basic calculus and the principle of graphic triangulation and intersection to be successful. Land surveyors are needed to resolve problems concerning roads, bridges, dams, and residential areas and they also determine the boundaries of private property and boundaries of political divisions. Modern surveying is closely related to the various branches of engineering, especially civil engineering. Land surveyors use many instruments to determine a correct and precise measurement.

Transits and theodolites, sighting instruments, began to replace the surveyor's compass in the 1800's. Transits can be used for observing horizontal and vertical angles, differences in elevation, and measuring distances by stadia. Theodolites are capable of greater accuracy in angle measurements than transits and are frequently used today. Both instruments measure angles and determine direction.

Modern Land Surveying Equipment

The most important surveying tool is the electronic total station, a small telescope equipped with an electronic distance-measuring device integrated into the theodolites. By measuring the distance and angles quickly, the relative position from the reference point can be computed.

GPS Land Surveying

Technology has brought many new advances in the field of land surveying, including the Global Positioning System or better known as GPS. GPS land surveying uses high precision GPS receivers to receive satellites transmission signals and then compute the relative position of the each receiver. Land surveyors could do all of their work with high-tech equipment and computers.