Land Surveying or Surveying involves measuring of dimensional relationships between points, lines, and physical attributes on or close to the Earth's surface. In essence, surveying involves measuring of horizontal distances, elevation differences, directions, and angles. Once these basic determinations or measurements are obtained, those are used later to the calculation of areas and volumes and to the fixing of locations concerning some coordinate system. Surveying, as we know, is mainly used to establish and measure property lines; to set out buildings, roads, bridges, waterways, sewers, and pipelines for construction; and to obtain topographic data for turning out maps and charts.
It is assumed that horizontal distances are parallel to a common plane. Similarly, each measurement provides both length and direction. Length is normally indicated in feet or in meters. The direction is given as a bearing of the azimuth angle to a reference meridian. The meridian is usually taken as the north-south direction. Moreover, the concept of control or reference point is applied to the position of lines as well as for their directions. The point of origin is established for the lines of surveys. Commonly, most coordinate systems have the origin placed west and south of the area to be surveyed, so that all coordinates are positive in the north-east quadrant. The Land Surveying involves vertical measurement which provides the third dimension to an object's position. Normally this dimension is given as a distance above some reference point or surface such as mean sea level, called the datum. Mean sea level is established by averaging high and low tide levels during a lunar month.
The Importance of Land Surveying
Land surveying is mainly focusing on establishment of property boundaries through systematic study, inspection, gathering information through field observations and measurements and study of legal instruments related to property. Similarly, it involves the re-establishment of cadastral surveys and land boundaries based on documented records and historical evidence. Land Surveying also include certifying surveys (as per the statute or local ordinance requirements) of subdivision plats/maps, registered land surveys, judicial surveys, and space delineation. Land surveying can also be associated with services such as mapping and related data accumulation, construction layout surveys, precision measurements of length, angle, elevation, area, and volume, as well as horizontal and vertical control surveys, and the analysis and utilization of land survey data.
It is essential to note that Land Surveying has been an important function in improvement of the the human environment. It has been an integral part of planning and implementation of any type of construction. Its latest usage has spanned into the field of transportation, buildings, telecommunications, mapping and establishment of legal boundaries of land ownership.
Instruments Used In Land Surveying
Until recently the basic tools used for land surveying were, tape measuring the short distances, a Level for determining the elevation differences, and theodolite for to measure the angles horizontally and vertically along with triangulation. Today, more sophisticated instrument such as total station is widely used. The total station is a theodolite with an electronic distant measurement device (EDM) which can be used for horizontal, vertical, angular measurements. Since the introduction of the total station, it has evolved from optical-mechanical device to fully computerized full electronic device. The top of the range total stations are no longer dependent on reflector or prism and are fully automatic or robotic, can even e-mail field data to the office computer via Global Position System (GPS). With such modern equipment, it has totally revolutionized the Land Surveying by way of speed and accuracy and less manpower.