Surveying

Surveying is the method and science of measuring the terrestrial three dimensional positions of point accurately and distance and angles between them. They are frequently used to create the land maps and boundaries for government purposes or some other purposes. Surveyors always use the elements of geometry, engineering, trigonometry, mathematics, physics, and law to get done their purpose. Surveying is an essential element in the growth of the human environment. It is most familiar in the fields of transport, building and construction, communications, mapping.

Land Surveying

Land surveying is the detailed study or inspections, collecting information through observations, field measurements, lot of questions or research of legal instruments, and analysis of data in the support of planning, designing and creating of proper boundaries. It will add up associated services such as mapping and related collected data, construction layout surveys, and exact measurement of length, angle, elevation, area, and volume, horizontal and vertical control surveys, and analysis and use of land survey data.

Surveying Techniques

Distances were measured using lot of means, such as Gunter’s chain, or measuring tapes made of steel. For measuring horizontal distances, these chains or tapes were pulled firm depends on temperature, to reduce drooping. In measuring up a slope, the surveyor might have to break the measurement, for that use an increment less than the total length of the chain. By using compass, the Horizontal angles were measured, which would provide the magnetic bearing; the deflection can be measured from that. The easiest method for measuring height is with an altimeter, normally a barometer using air pressure as an indication of height.  By Triangulation method: distance, elevation, and direction between objects at greater distance from one another can be easily determined.

Equipment used for surveying

In 1990s the tools used to measure shorter distances, and to determine height and elevation, were a tape measure. Total station is the modern instrument which is called theodolite with an electronic measurement device. A total station is used for leveling when it is set for horizontal plane. It is still used along with the other types of surveying instruments. Global positioning systems (GPS) do not work well in the dense areas.  The faster but very expensive way to measure wide areas is with the helicopter, which is equipped with the laser scanner, combined with a GPS to determine the position and elevation of the helicopter. Beacons are positioned on the ground about 20 km apart to increase the accuracy.  This method reaches the accuracy between 5 -40 cm, but it depends on flight height.

Questions:

• What is surveying?
• Explain the surveying techniques?