What is a topographical survey and why would I need one?
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Posted On :
Dec-22-2011
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Article Word Count :
474
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Topography is a measure of the relief of the land, and there are many different methods and techniques to the science.
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A topographical survey is a way to determine the configuration of the earth’s surface. It generally concerns the relief of the earth (or planet, moon or asteroid), which can also include artificial and natural feature such as valley, streams, dams, bridges and buildings. The recording of relief or terrain involves determining the terrestrial or three-dimensional space position of points and the distances and angles between them. A graphic representation of the relief of an area is called a topographic map, which will be constructed from data which shows the horizontal and vertical locations plotted in the survey. Digital surface models and digital terrain models can show the 3D representation of the results of a topographical survey, with or without objects such as plants or buildings.
A topographical survey is a form of land surveying which measures the elevation of plots on a particular piece of land, which are presented as contour lines on a plot. A topographical survey uses astheodolites, dumpy levels and clinometers, which will measure the distances and angles between points. Direct surveys such as these can be manual or GIS-based, the latter being a computerised system used to capture, store, manipulate, analyse, manage and present the findings of the topographical survey.
A topographical survey may be conducted for a number of reasons. The purpose is to determine points in a horizontal coordinate system such as latitude, longitude and altitude. This might be commissioned by architects and engineers before planning the construction of a building or its drainage. They are also carried out for other reasons such as archaeological digs, military planning and geological exploration and mapping.
There are other types of topological survey than a direct survey. Remote sensing is described as geodata collected at a distance from the subject area. Aerial and satellite imagery are a part of geovisualisation. Aerial and satellite imagery use a non-visual spectra of light to determine the lie of the land, showing vegetation and other land use information in a more detailed way. Photogammetry can be used to create surveys of a 3D surface by using a number of photographs taken from different positions, usually from different passes of an aerial flight.
Radar and sonar are used to generate Digital Elevation Models. Using sonar to determine the terrain of the ocean floor is an example of sonar mapping in use. A light detection remote sensing technique is another method being used in topography, which uses a laser instead of radio waves.
Topography is also used in other fields. In neuroscience, brain mapping uses EEG topography, and in ophthalmology corneal topography is used as a technique for mapping the surface curvature of the cornea. In anatomy, topography is superficial human anatomy. In mathematics the concept of topography is used to indicate patterns in variables in a space or map.
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Article Source :
http://www.articleseen.com/Article_ What is a topographical survey and why would I need one? _122918.aspx
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Author Resource :
SUMO Surveying Services are a multi-disciplinary survey business committed to maintaining the highest standards in all aspects of surveying. SUMO’s services include topographical surveys, as well as utility detection, utility mapping and measured building surveys.SUMO are the industry experts in topographical surveying
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Keywords :
Topographical survey,
Category :
Computers
:
Computers
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