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Encyclopedia > Topography
A topographic map with contour intervals
A topographic map with contour intervals

Topography (Greek topos, "place", and graphia, "writing") is the study of Earth's surface features or those of other planets, moons, and asteroids. Description: Example of a topographic map with contour intervals Source: Sample taken from the public domain USGS Digital Raster Graphic file o44072d6. ... Description: Example of a topographic map with contour intervals Source: Sample taken from the public domain USGS Digital Raster Graphic file o44072d6. ... Any of the spaces between vertical lines on a topographic map or globe; the difference in elevation such an interval represents Ex. ... Adjectives: Terrestrial, Terran, Telluric, Tellurian, Earthly Atmosphere Surface pressure: 101. ... An open surface with X-, Y-, and Z-contours shown. ... The eight planets and three dwarf planets of the Solar System. ... A natural satellite is an object that orbits a planet or other body larger than itself and which is not man-made. ... Asteroids is a popular vector-based video arcade game released in 1979 by Atari. ...


In a broader sense, topography is concerned with local detail in general, including not only relief but also vegetative and human-made features, and even local history and culture. This meaning is less common in America, where topographic maps with elevation contours have made "topography" synonymous with relief. The older sense of Topography as the study of place still has currency in Europe. Vegetation is a general term for the plant life of a region; it refers to the ground cover provided by plants, and is, by far, the most abundant biotic element of the biosphere. ... Local history is the study of the history of a relatively small geographic area; typically a specific settlement, parish or county. ... Culture (from the Latin cultura stemming from colere, meaning to cultivate), generally refers to patterns of human activity and the symbolic structures that give such activity significance. ... The Topography and Monuments of Ancient Rome Starting in Ancient Greece, places have been described in topography (), and an author of such writing has been called a topographer (). Greek and Roman topographers provide much of the basis of modern reconstructions of the fabric of the cities of Classical times (especially...


For the purposes of this article, topography specifically involves the recording of relief or terrain, the three-dimensional aspect of the surface, and the identification of specific landforms. This is also known as geomorphometry. In modern usage, this involves generation of elevation data in electronic form. It is often considered to include the graphic representation of the landform on a map by a variety of techniques, including contour lines, Hypsometric tints, and relief shading.[1][2][3] A landform comprises a geomorphological unit. ... It has been suggested that this article or section be merged into Topography. ... A map is a simplified depiction of a space which highlights relations between components (objects, regions) of that space. ... Terrain or relief is an essential aspect of physical geography, and as such its portrayal presents a central problem in cartography, and more recently GIS and 3D Visualization. ... Elevation contour map A contour line shows elevation. ... The Moon - The color of the map represents the elevation. ... It has been suggested that this article or section be merged into Cartographic relief depiction. ...

Contents

Etymology

The term “topography” originated in Ancient Greece and continued in Ancient Rome, as the detailed description of a place. The word comes from the Greek words τόπος (topos, place) and γραφία (graphia, writing).[4] In classical literature this refers to writing about a place or places, what is now largely called 'local history'. In Britain and in Europe in general, the word topography is still sometimes used in its original sense[5]. The Temple to Athena, the Parthenon Ancient Greece is a period in Greek history that lasted for around three thousand years. ... Ancient Rome was a civilization that grew from a small agricultural community founded on the Italian Peninsula circa the 9th century BC to a massive empire straddling the Mediterranean Sea. ... This list is incomplete; you can help by expanding it. ... Local history is the study of the history of a relatively small geographic area; typically a specific settlement, parish or county. ...


Detailed military surveys in Britain (beginning in the late eighteenth century) were called Ordnance Surveys, and this term was used into the 20th century as generic for topographic surveys and maps[6]. The earliest scientific surveys in France were called the Cassini maps after the family who produced them over four generations [7]. The term "topographic surveys" appears to be American in origin. The earliest detailed surveys in the United States were made by the “Topographical Bureau of the Army,” formed during the War of 1812 [8]. After the work of national mapping was assumed by the U.S. Geological Survey in 1878, the term topographical remained as a general term for detailed surveys and mapping programs, and has been adopted by most other nations as standard. Part of an Ordnance Survey map at 1 inch to the mile scale from 1945 Ordnance Survey (OS) is an executive agency of the United Kingdom government. ... This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... Combatants United States Great Britain Canada Bermuda Eastern Woodland Indians Commanders James Madison Henry Dearborn Jacob Brown Winfield Scott Andrew Jackson George Prevost Isaac Brock† Tecumseh† Strength •U.S. Regular Army: 35,800 •Rangers: 3,049 •Militia: 458,463* •US Navy & US Marines: (at start of war): •Frigates:6 •Other... The United States Geological Survey (USGS) is a scientific agency of the United States government. ...


In the 20th century, the term topography started to be used to describe surface description in other fields where mapping in a broader sense is used, partcularly in medical fields such as neurology. The word mapping has several senses: In mathematics and related technical fields, it is some kind of function: see map (mathematics). ... Neurology is a branch of medicine dealing with disorders of the nervous system. ...


Objectives

The objective of topography is to determine the position of any feature or more generally any point in terms of both a horizontal Coordinate system such as latitude and longitude, and altitude. Identifying (naming) features and recognizing typical landform patterns are also part of the field. In mathematics as applied to geometry, physics or engineering, a coordinate system is a system for assigning a tuple of numbers to each point in an n-dimensional space. ... Altitude is the elevation of an object from a known level or datum. ...


A topographic study may be made for a variety of reasons: military planning and geological exploration have been primary motivators to start survey programs, but detailed information about terrain and surface features is essential for the planning and construction of any major civil engineering, public works, or reclamation projects. Surveyor at work with a leveling instrument. ... This article or section does not cite any references or sources. ... This article or section does not cite any references or sources. ... The Falkirk Wheel in Scotland. ... Look up Public works in Wiktionary, the free dictionary. ... Land reclamation is either of two distinct practices. ...


Techniques of topography

There are a variety of approaches to studying topograpy. Which method(s) to use depend on the scale and size of the area under study, its accessibility, and the quality of existing surveys.


Direct survey

A surveying point in Germany
A surveying point in Germany
Main article: Surveying

Surveying helps determine accurately the terrestrial or three-dimensional space position of points and the distances and angles between them using leveling instruments such as theodolites, dumpy levels and clinometers. Image File history File links Download high-resolution version (800x800, 334 KB) en: Description: A surveying point (Is this the correct translation?). Photo taken in Tübingen, Germany. ... Image File history File links Download high-resolution version (800x800, 334 KB) en: Description: A surveying point (Is this the correct translation?). Photo taken in Tübingen, Germany. ... Surveyor at work with a leveling instrument. ... The space we live in is three-dimensional space. ... Look up position in Wiktionary, the free dictionary. ... Dumpy level in use on a construction site A dumpy level, builders auto level, leveling instrument or automatic level is an instrument used in surveying and building to transfer, measure, or set horizontal levels. ... An optical theodolite, manufactured in the Soviet Union in 1958 and used for topographic surveying. ... also known as a transit level. ... It has been suggested that Inclinometer be merged into this article or section. ...


Even though remote sensing has greatly speeded up the process of gathering information, and has allowed greater accuracy control over long distances, the direct survey still provides the basic control points and framework for all topographic work, whether manual or GIS-based. A geographic information system (GIS) is a system for managing data that has a spatial specialized form of an information system. ...


In areas where there has been an extensive direct survey and mapping program (most of Europe and the Continental US, for example), the compiled data forms the basis of basic digital elevation datasets such as USGS DEM data. This data must often be "cleaned" to eliminate discrepancies between surveys, but it still forms a valuable set of information for large-scale analysis. The USGS DEM standard is a geospatial file format developed by the United States Geological Survey for storing a digital elevation model (or surface elevation). ...


The original American topographic surveys (or the British "Ordnance" surveys) involved not only recording of relief, but identification of landmark features and vegetative land cover.


Remote sensing

Main article: Remote sensing

Remote sensing is a general term for geodata collection at a distance from the subject area. Synthetic aperture radar image of Death Valley colored using polarimetry In the broadest sense, remote sensing is the measurement or acquisition of information of an object or phenomenon, by a recording device that is not in physical or intimate contact with the object. ... Synthetic aperture radar image of Death Valley colored using polarimetry In the broadest sense, remote sensing is the measurement or acquisition of information of an object or phenomenon, by a recording device that is not in physical or intimate contact with the object. ...


Aerial and satellite imagery

Main article: Aerial photography
Main article: Satellite imagery

Besides their role in photogrammetry, aerial and satellite imagery can be used to identify and delineate terrain features and more general land-cover features. Certainly they have become more and more a part of geovisualization, whether maps or GIS systems. False-color and non-visible spectra imaging can also help determine the lie of the land by delineating vegetation and other land-use information more clearly. Images can be in visible colours and in other spectra. The Georgian terrace of Royal Crescent (Bath, England) from a hot air balloon Dulles Airport in Reston, Virginia, from an airplane Intersection of E42 and E451 from an aircraft soon after takeoff from Frankfurt International Airport Moreton Island in Queensland, Australia Aerial photography is the taking of photographs from the... NASA Goddard Space Flight Center Image Satellite imagery consists of photographs of Earth or other planets made from artificial satellites. ... See map for the navigational aid The acronym MAPS could refer to: Multidisciplinary Association for Psychedelic Studies Mail Abuse Prevention System Multi-jurisdictional Automated Preclearance System Mid-Atlantic Percussion Society Medical Advanced Pain Specialists Monitoring Avian Productivity and Survivorship Multidisciplinary Academic PerspectiveS Metropolitan Area ProjectS Category: ... A geographic information system (GIS) is a system for managing data that has a spatial specialized form of an information system. ... Spectra are conditions or values that vary over a continuum. ... Spectra are conditions or values that vary over a continuum. ...


Photogrammetry

Main article: Photogrammetry

Photogrammetry is a measurement technique for which the co-ordinates of the points in 3D of an object are determined by the measurements made in two photographic images (or more) taken starting from different positions, usually from different passes of an aerial photography flight. In this technique, the common points are identified on each image. A line of sight (or ray) can be built from the camera location to the point on the object. It is the intersection of its rays (triangulation) which determines the relative three-dimensional position of the point. Known control points can be used to give these relative positions absolute values. More sophisticated algorithms can exploit other information on the scene known a priori (for example, symmetries in certain cases allowing the rebuilding of three-dimensional co-ordinates starting from one only position of the camera). Photogrammetry is a measurement technology in which the three-dimensional coordinates of points on an object are determined by measurements made in two or more photographic images taken from different positions (see stereoscopy). ... The Cartesian coordinate system. ... The space we live in is three-dimensional space. ... Lens and mounting of a large format camera Photography is the technique of recording and generating permanent images, by the capturing and preservation of physical stimulus-patterns on a layer of photosensitive material. ... It has been suggested that this article or section be merged into image (disambiguation). ... Look up ray in Wiktionary, the free dictionary. ... Triangulation can be used to find the distance from the shore to the ship. ... In mathematics, computing, linguistics, and related disciplines, an algorithm is a finite list of well-defined instructions for accomplishing some task that, given an initial state, will terminate in a defined end-state. ...


Radar and sonar

Satellite radar mapping is one of the major techniques of generating Digital Elevation Models (see below). Similar techniques are applied in bathymetric surveys using sonar to determine the terrain of the ocean floor. This long range radar antenna, known as ALTAIR, is used to detect and track space objects in conjunction with ABM testing at the Ronald Reagan Test Site on the Kwajalein atoll. ... Bathymetry is the underwater equivalent to topography. ... The F70 type frigates (here, La Motte-Picquet) are fitted with VDS (Variable Depth Sonar) type DUBV43 or DUBV43C towed sonars SONAR (SOund Navigation And Ranging) â€” or sonar â€” is a technique that uses sound propagation under water (primarily) to navigate, communicate or to detect other vessels. ...


Forms of topographic data

Terrain is commonly modelled either using vector (Triangulated Irregular Network or TIN) or gridded (Raster image) mathematical models. In the most applications in environmental sciences, land surface is represented and modelled using gridded models. In civil engineering and entertainment businesses, the most representations of land surface employ some variant of TIN models. In geostatistics, land surface is commonly modelled as a combination of the two signals - the smooth (spatially correlated) and the rough (noise) signal. Suppose the smiley face in the top left corner is an RGB bitmap image. ... This article or section is in need of attention from an expert on the subject. ...


In practice, surveyors first sample heights in an area, then use these to produce a Digital Surface Model (also known as a digital elevation model). The DLSM can then be used to visualize terrain, drape remote sensing images, quantify ecological properties of a surface or extract land surface objects. Note that the contour data or any other sampled elevation datasets are not a DLSM. A DLSM implies that elevation is available continuously at each location in the study area, i.e. that the map represents a complete surface. Digital Land Surface Models should not be confused with Digital Surface Models, which can be surfaces of the canopy, buildings and similar objects. For example, in the case of surface models produces using the LIDAR technology, one can have several surfaces - starting from the top of the canopy to the actual solid earth. The difference between the two surface models can then be used to derive volumetric measures (height of trees etc). 3D rendering of a DEM of Tithonium Chasma on Mars A digital elevation model (DEM) is a digital representation of ground surface topography or terrain. ... This article or section does not adequately cite its references or sources. ...


Raw survey data

Topographic survey information is historically based upon the notes of surveyors. They may derive naming and cultural information from other local sources (for example, boundary delineation may be derived from local cadastral mapping. While of historical interest, these field notes inherently include errors and contradictions that later stages in map production resolve. Look up Boundary in Wiktionary, the free dictionary. ... Cadastral is a term used in surveying and public administration, and refers to the division of land into units for surveying, taxation or administrative purposes. ...


Remote sensing data

As with field notes, remote sensing data (aerial and satellite photography, for example), is raw and uninterpreted. It may contain holes (due to cloud cover for example) or inconsistencies (due to the timing of specific image captures). Most modern topographic mapping includes a large component of remotely sensed data in its compilation process.


Topographic mapping

Main article: Topographic map
A map of Europe using elevation modeling
A map of Europe using elevation modeling

In its contemporary definition, topographic mapping shows relief. In the United States, USGS topographic maps show relief using contour lines. The USGS calls maps based on topographic surveys, but without contours, "planimetric maps." Example of a topographic map with contour lines Part of the same map in a perspective shaded relief view illustrates how the contour lines of the original follow the terrain Topographic maps are a variety of map characterized by large-scale detail and quantitative representation of relief, usually using contour... Image File history File links Download high-resolution version (1475x1200, 773 KB) Description: topography in Europe, map Source: own map, based on the Generic Mapping Tools and ETOPO2 Author: San Jose, 2 April 2006 Other versions: map in English, map in German, map in French Beschreibung: Topografie in Europa, Karte... Image File history File links Download high-resolution version (1475x1200, 773 KB) Description: topography in Europe, map Source: own map, based on the Generic Mapping Tools and ETOPO2 Author: San Jose, 2 April 2006 Other versions: map in English, map in German, map in French Beschreibung: Topografie in Europa, Karte... World map showing the location of Europe. ... The United States Geological Survey (USGS) is a scientific agency of the United States government. ... Contour map A contour line (also isopleth, level set, isogram or isarithm) for a function of two variables is a curve connecting points where the function has a particular value. ...


These maps show not only the contours, but also any significant streams or other bodies of water, forest cover, built-up areas or individual buildings (depending on scale), and other features and points of interest. Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... A forest What is a Plantation forest? Ariy Fik is an area with a high density of trees (or, historically, a wooded area set aside for hunting). ...


While not officially "topographic" maps, the national surveys of other nations share many of the same features, and so they are often generally called "topographic maps."


Existing topographic survey maps, because of their comprehensive and encyclopedic coverage, form the basis for much derived topographic work. Digital Elevation Models, for example, have often been created not from new remote sensing data but from existing paper topographic maps. Many government and private publishers use the artwork (especially the countour lines) from existing topographic map sheets as the basis for their own specialized or updated topographic maps[9]


Topographic mapping should not be confused with Geologic mapping. The latter is concerned with underlying structures and processes to the surface, rather than with identifiable surface features. A geologic map is a special-purpose map made for the purpose of showing subsurface geological features. ...


Digital elevation modeling

3D rendering of a DEM used for the topography of Mars
3D rendering of a DEM used for the topography of Mars

The digital elevation model (DEM) is a raster-based digital dataset of the topography (altimetry and/or bathymetry) of all or part of the Earth (or a telluric planet). The pixels of the dataset are each assigned an elevation value, and a header portion of the dataset defines the are of coverage, the units each pixel covers, and the units of elevation (and the zero-point). DEMs may be derived from exisitng paper maps and survey data, or they may be generated from new satellite or other remotely-sensed radar or sonar data. 3D rendering of a DEM of Tithonium Chasma on Mars A digital elevation model (DEM) is a digital representation of ground surface topography or terrain. ... Image File history File links Download high-resolution version (1274x972, 522 KB) 3D view of elevation model of Tithonium Chasma From http://astrogeology. ... Image File history File links Download high-resolution version (1274x972, 522 KB) 3D view of elevation model of Tithonium Chasma From http://astrogeology. ... 3D rendering of a DEM of Tithonium Chasma on Mars A digital elevation model (DEM) is a digital representation of ground surface topography or terrain. ... Topographic map of Mars, courtesy NASA Goddard Space Flight Center, from Mars Global Surveyor laser altimeter research led by Maria Zuber and David Smith. ... Suppose the smiley face in the top left corner is an RGB bitmap image. ... A digital system is one that uses discrete values (often electrical voltages), especially those representable as binary numbers, or non-numeric symbols such as letters or icons, for input, processing, transmission, storage, or display, rather than a continuous spectrum of values (ie, as in an analog system). ... Diagram showing the face of a three-pointer sensitive aircraft altimeter displaying altitude in feet. ... Bathymetry is the underwater equivalent to topography. ... The inner planets, their sizes to scale. ... A pixel (a contraction of picture element) is one of the many tiny dots that make up the representation of a picture in a computers memory. ... This long range radar antenna, known as ALTAIR, is used to detect and track space objects in conjunction with ABM testing at the Ronald Reagan Test Site on the Kwajalein atoll. ... The F70 type frigates (here, La Motte-Picquet) are fitted with VDS (Variable Depth Sonar) type DUBV43 or DUBV43C towed sonars SONAR (SOund Navigation And Ranging) â€” or sonar â€” is a technique that uses sound propagation under water (primarily) to navigate, communicate or to detect other vessels. ...


Topological modeling

A geographic information system (GIS) can recognize and analyze the spatial relationships that exist within digitally stored spatial data. These topological relationships allow complex spatial modelling and analysis to be performed. Topological relationships between geometric entities traditionally include adjacency (what adjoins what), containment (what encloses what), and proximity (how close something is to something else). A geographic information system (GIS) is a system for capturing, storing, analyzing and managing data and associated attributes which are spatially referenced to the earth. ... An abstract model (or conceptual model) is a theoretical construct that represents physical, biological or social processes, with a set of variables and a set of logical and quantitative relationships between them. ...

  • reconstitute a sight in synthesized images of the ground,
  • determine a trajectory of overflight of the ground,
  • calculate surfaces or volumes,
  • trace topographic profiles,
  • handle in a quantitative way the studied ground.

Topography in other fields

Topography has been applied to different science fields. In neuroscience, the neuroimaging discipline uses techniques such as EEG topography for brain mapping. In ophthalmology, corneal topography is used as a technique for mapping the surface curvature of the cornea. Drawing of the cells in the chicken cerebellum by S. Ramón y Cajal Neuroscience is a field that is devoted to the scientific study of the nervous system. ... Neuroimaging includes the use of various techniques to either directly or indirectly image the structure, function, or pharmacology of the brain. ... Typical EEG brain topography display With the possibility of recording simultaneously a great number of digitized channels of EEG, a new technique was born: EEG brain topography, at the end of the 80s. ... It has been suggested that this article or section be merged into Neuroimaging. ... This does not adequately cite its references or sources. ... A corneal topogram. ... The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber, providing most of an eyes optical power [1]. Together with the lens, the cornea refracts light and, as a result, helps the eye to focus. ...


See also

Cartography or mapmaking (in Greek chartis = map and graphein = write) is the study, practice, science and art of making maps or globes. ... The Topography and Monuments of Ancient Rome Starting in Ancient Greece, places have been described in topography (), and an author of such writing has been called a topographer (). Greek and Roman topographers provide much of the basis of modern reconstructions of the fabric of the cities of Classical times (especially... Surface of the Earth Geomorphology is the study of landforms, including their origin and evolution, and the processes that shape them. ...

References and notes

  1. ^ What is topography? - Center for Geographic Information
  2. ^ Definition from WordNet Search - princeton.edu
  3. ^ Definition from Federal Citizen Information Center - pueblo.gsa.gov
  4. ^ Online Etymology Dictionary - etymonline.com
  5. ^ For example, see the website of the London Topographical Society
  6. ^ Oxford English Dictionary "Ordnance Survey"
  7. ^ http://fr.wikipedia.org/wiki/Cartographie#Histoire#France
  8. ^ http://www.topogs.org/History.htm
  9. ^ see for example the publications of National Geographic Trails Illustrated Maps and Delorme products

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Topography is the physical shape of the land, particularly as it relates to elevation.
Topography is a general term in geography, derived from the Greek "topos" (place) and "graphein" (to draw), and refers to the lie of the land, or various other characteristics of Physical geography in a region; this is usually expressed in terms of the elevation, slope, and orientation of terrain features.
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