Topographic-surveyors-in-Dubai
Survey Methodology
Topographic-surveyors-in-Dubai a. GPS Survey
The Global Positioning System (GPS) is a satellite-based positioning system made up of a network of 24 satellites placed into orbit by the U.S. Department of Defense. GPS satellites circle the earth twice a day in a very precise orbit and transmit signal information to earth. GPS receivers take this information and use triangulation to calculate the exact position of them. GPS receiver compares the time a signal was transmitted by a satellite with the time it was received. The time difference tells the GPS receiver how far away the satellite is. With the distance measurements from a few more satellites, the receiver can determine its position with centimeter accuracy.

b. Total station survey
A total station is an optical instrument used in modern surveying. It is a combination of an electronic theodolite (transit), an electronic distance meter (EDM) and software running on an external computer known as data collector. A total station allows the surveyor to store all information he needs to establish a setting out and can store all information taken from site as existing features, original ground levels, road edges, etc.
Also the remote measurements are facilitated by the total station where a direct access is not available. For example the height of street light poles, ground clearance of overhead power lines, etc.

c. Theodolite survey
A theodolite is an instrument for measuring both horizontal and vertical angles, as used in triangulation networks. It is the old, mechanical / manual version of total station. Theodolite survey widely using for single line executions like pipe lines, cable routes, curb lines, road centre lines, etc. A modern theodolite consists of a movable telescope mounted within two perpendicular axes—the horizontal or trunnion axis, and the vertical axis. When the telescope is pointed at a desired object, the angle of each of these axes can be measured with great precision, typically on the scale of arcseconds.

d. Dumpy levels survey
A dumpy level is an optical instrument used in surveying to transfer, measure, or set horizontal levels with reference to the mean sea level or available approved datum precisely. The instrument and staff are used to gather and/or transfer elevations (levels) during site surveys. Measurement generally starts from a benchmark with known height determined by a previous survey, or an arbitrary point with an assumed height