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Land Survey

written by: Finn Orfano • edited by: Swagatam • updated: 1/30/2010

Surveying is an old technique that has advanced from the use of simple measuring instruments to the use of modern precise instruments. GPS map coordinates and automated total stations are now easily available that are used to indicate an accurate location of geographical areas.

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    What is Land Surveying

    Land surveying is also known as Geomatics, and is one of the oldest profession in the world. It existed during the period of the Egyptians and the Babylonians. It is basically the science related to the measurement and land mapping, to determine the land boundaries. It is this science that enables construction of roads, erection of skyscrapers, and marking of the individual land boundaries. The GPS map coordinates and automated total stations are essential tools for the land surveying. It provides an accurate land survey description, and ensures proper alignment of the roads and airports. Surveying is significant for the design and construction of structures. The land topography is mapped for engineering design, title surveys are performed for real state business, and buildings are laid. In addition, the river boundaries are plotted for dredging; corridors are marked for roads, railroads, tunnels, and airports.WHAT IS LAND SURVEYING 

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    Surveying Techniques

    Global Positioning System

    Global Positioning System is an important surveying tool that is used for indicating accurate location of points. Signals are sent to receiver through satellites, and transmitted to data collector where the data is stored. This data is fed to computers where the software obtains precise location of points. The information obtained is highly accurate within some millimeters.GLOBAL POSITIONING SYSTEM 

    Total Station Surveying

    The main tasks involved in surveying are observing, measurement, and mapping. Total station is one of the important tools that are extensively used for these purposes. A total station includes a device for the measurement of distances, and also a theodolite for determining the angles. Measurements are taken by directing a beam of infrared light in the direction of a prism. The light is reflected from the prism towards the total station. The time taken for the return of light is measured that indicates the distance of the prism.

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    Differential Leveling

    Differential leveling is essentially a system used to establish the variations in elevations between positions that are distant from each other. An elevation is a perpendicular distance below or above a reference point. A level, graduated rods, and a tripod are used for the measurement of differential leveling. A level has essentially three main parts, namely a telescope, a leveling tool, and a leveling tube.DIFFERENTIAL LEVELLING 

    Types Differential Leveling

    With the advancement in survey equipment due to the extensive growth in the technological fields, the leveling techniques have also been developed considerably. Kinds of levels utilized in differential leveling are digital, automatic, and optical.

    Digital Leveling

    Electronic image processing is used to establish distances and heights, and for the automatic recording of data in a PC. It is capable to automatically execute usual optical measurements. The instrument obtains and handles the bar image. The processed image is evaluated and programmed in the memory. The differences in the distance and height are ascertained.

    Automatic Leveling

    A prism that can move freely is used for the automatic orientation of the line of sight. The prism is balanced by a fulcrum. The tool can be leveled rapidly by using a circular bubble. With the bubble located at the centre position, a straight line of sight is maintained. These tools can be arranged fast and are simple in use.

    Optic Leveling

    The design of optical levels is comparable to the automatic levels. A plane parallel plate lens is used that is rotated. The line of sight of a light ray is deflected vertically. An optical micrometer is used for leveling.OPTICAL LEVELLING