Topography (topo-, "place", and graphia, "writing") is the study of Earth's surface features or those of planets, moons, and asteroids. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 In Mathematics, specifically in Topology, a surface is a Two-dimensional Manifold. A planet, as defined by the International Astronomical Union (IAU is a celestial body Orbiting a Star or stellar remnant that is A natural satellite or moon is a Celestial body that Orbits a Planet or smaller body which is called the primary. Asteroids, sometimes called Minor planets or planetoids', are bodies—primarily of the inner Solar System —that are smaller than planets but
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. Vegetation is a general term for the plant life of a region it refers to the Ground cover provided by plants Local history is the study of History in a geographically local context Culture (from the Latin cultura stemming from colere, meaning "to cultivate" generally refers to patterns of human activity and the symbolic This meaning is less common in America, where topographic maps with elevation contours have made "topography" synonymous with relief. The elevation of a Geographic location is its height above a fixed reference point often the mean sea level. The older sense of topography as the study of place still has currency in Europe. See also Topography Starting in Ancient Greece, places have been described in topography ( and an author of such writing has been called a
For the purposes of this article, topography specifically involves the recording of relief or terrain, the three-dimensional quality of the surface, and the identification of specific landforms. Terrain, or relief, is the third or vertical dimension of land surface. This is also known as geomorphometry. Geomorphometry is the science of quantitative Land surface analysis 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. A map is a visual representation of an area—a symbolic depiction highlighting relationships between elements of that space such as objects, Regions, and Themes 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 A contour line (also Level set, isopleth, isoline, isogram or isarithm) of a function of two 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 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 [1][2][3]
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Etymology
The term topography originated in ancient Greece and continued in ancient Rome, as the detailed description of a place. The term ancient Greece refers to the period of Greek history lasting from the Greek Dark Ages ca Ancient Rome was a Civilization that grew out of a small agricultural community founded on the Italian Peninsula as early as the 10th century BC The word comes from the Greek words τόπος (topos, place) and γραφία (graphia, writing). This is a list of Greek words with derivatives in English (and other modern languages [4] In classical literature this refers to writing about a place or places, what is now largely called 'local history'. Local history is the study of History in a geographically local context In Britain and in Europe in general, the word topography is still sometimes used in its original sense[5].
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]. Ordnance Survey (OS is an Executive agency of the United Kingdom government 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]. The War of 1812 was fought between the United States of America and the British Empire, particularly Great Britain and her North American colonies 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. 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.
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. In Mathematics and its applications a coordinate system is a system for assigning an n - Tuple of Numbers or scalars to each point Altitude is the Elevation of a point or object from a known level or datum (plural data Identifying (naming) features and recognizing typical landform patterns are also part of the field.
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. Surveying is the technique and science of accurately determining the terrestrial or three-dimensional space Position of points and the distances and angles between Terrain, or relief, is the third or vertical dimension of land surface. Planning in Organizations and Public policy is both the organizational process of creating and maintaining a Plan; and the psychological process of In the fields of Architecture and Civil engineering, construction is a process that consists of the Building or assembling of Infrastructure Civil engineering is a professional engineering discipline that deals with the design construction and maintenance of the physical and naturally built Public works are the construction or engineering projects carried out by the State on behalf of the Community. See Reclaim for other uses Reclamation is the process of reclaiming something from loss or from a less useful condition
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
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. Germany, officially the Federal Republic of Germany ( ˈbʊndəsʁepuˌbliːk ˈdɔʏtʃlant is a Country in Central Europe. Surveying is the technique and science of accurately determining the terrestrial or three-dimensional space Position of points and the distances and angles between Three-dimensional space is a geometric model of the physical Universe in which we live A dumpy level, builder's auto level, leveling instrument or automatic level is an optical instrument used in Surveying and building A theodolite ( is an instrument for measuring both horizontal and vertical Angles as used in Triangulation networks A dumpy level, builder's auto level, leveling instrument or automatic level is an optical instrument used in Surveying and building An inclinometer or clinometer is an instrument for measuring angles of Slope (or Tilt) Elevation or Inclination of an object with
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.
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. The USGS DEM standard is a Geospatial File format developed by the United States Geological Survey for storing a raster -based Digital elevation 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 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
Remote sensing is a general term for geodata collection at a distance from the subject area. Remote sensing is the small or large-scale acquisition of information of an object or phenomenon by the use of either recording or real-time sensing device(s that is not in physical Remote sensing is the small or large-scale acquisition of information of an object or phenomenon by the use of either recording or real-time sensing device(s that is not in physical
Aerial and 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. Aerial photography is the taking of Photographs of the ground from an elevated position Satellite imagery consists of photographs of Earth or other planets made by means of Artificial satellites. Certainly they have become more and more a part of geovisualization, whether maps or GIS systems. A map is a visual representation of an area—a symbolic depiction highlighting relationships between elements of that space such as objects, Regions, and Themes 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.
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. Photogrammetry is the first Remote sensing technology ever developed in which geometric properties about objects are determined from photographic images In Mathematics and its applications a coordinate system is a system for assigning an n - Tuple of Numbers or scalars to each point Three-dimensional space is a geometric model of the physical Universe in which we live Photography (fә'tɒgrәfi or fә'tɑːgrәfi (from Greek φωτο and γραφία is the process and Art of recording pictures by means of capturing An image (from Latin imago) or picture is an artifact usually two-dimensional that has a similar appearance to some subject &mdashusually 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. In Optics, a ray is an idealized narrow Beam of light. Rays are used to model the propagation of Light through an optical system by dividing the real light It is the intersection of its rays (triangulation) which determines the relative three-dimensional position of the point. In Trigonometry and Geometry, triangulation is the process of determining the location of a point by measuring angles to it from known points at either 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). In Mathematics, Computing, Linguistics and related subjects an algorithm is a sequence of finite instructions often used for Calculation
Radar and sonar
Satellite radar mapping is one of the major techniques of generating Digital Elevation Models (see below). Radar is a system that uses electromagnetic waves to identify the range altitude direction or speed of both moving and fixed objects such as Aircraft, ships Similar techniques are applied in bathymetric surveys using sonar to determine the terrain of the ocean floor. Bathymetry is the underwater equivalent to Hypsometry. The name comes from Greek βαθυς deep, and μετρον measure. Sonar (which started as an Acronym for sound navigation and ranging) is a technique that uses Sound propagation (usually underwater to navigate
Forms of topographic data
Terrain is commonly modelled either using vector (Triangulated Irregular Network or TIN) or gridded (Raster image) mathematical models. In Computer graphics, a raster graphics image or bitmap, is a Data structure representing a generally rectangular grid of Pixels 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. Geostatistics evolved in Mineral exploration and mining of Minerals Ores and Coals It is currently applied in disciplines such as Petroleum
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). A digital elevation model ( DEM) is a Digital representation of ground Surface Topography or Terrain. 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. LIDAR ( Li ght D etection a nd R anging is an optical remote sensing technology that measures properties of scattered light to find range and/or The difference between the two surface models can then be used to derive volumetric measures (height of trees etc).
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. For a different notion of boundary related to Manifolds see that article A cadastre (also spelled cadaster) is a comprehensive register of the Metes and bounds real property of a country and commonly includes details of While of historical interest, these field notes inherently include errors and contradictions that later stages in map production resolve.
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
In its contemporary definition, topographic mapping shows relief. A topographic map is a type of Map characterized by large-scale detail and quantitative representation of relief, usually using Contour lines in modern In the United States, USGS topographic maps show relief using contour lines. The United States Geological Survey ( USGS) is a scientific agency of the United States government. A contour line (also Level set, isopleth, isoline, isogram or isarithm) of a function of two The USGS calls maps based on topographic surveys, but without contours, "planimetric maps. "
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. Water is a common Chemical substance that is essential for the survival of all known forms of Life. A forest is an area with a high density of Trees There are many definitions of a forest based on various criteria
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. A geologic map or geological map is a special-purpose Map made to show Geological features The latter is concerned with underlying structures and processes to the surface, rather than with identifiable surface features.
Digital elevation modeling
The digital elevation model (DEM) is a raster-based digital dataset of the topography (hypsometry and/or bathymetry) of all or part of the Earth (or a telluric planet). A digital elevation model ( DEM) is a Digital representation of ground Surface Topography or Terrain. A digital elevation model ( DEM) is a Digital representation of ground Surface Topography or Terrain. The "geography" of Mars, also known as areography, entails the delineation and characterization of regions on Mars. A digital system uses discrete (discontinuous values usually but not always Symbolized Numerically (hence called "digital" to represent information for Hypsometry is the measurement of land Elevation relative to Sea level. Bathymetry is the underwater equivalent to Hypsometry. The name comes from Greek βαθυς deep, and μετρον measure. A terrestrial planet, telluric planet or rocky planet is a Planet that is primarily composed of Silicate rocks Within our 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). In Digital imaging, a pixel ( pict ure el ement is the smallest piece of information in an image 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. Radar is a system that uses electromagnetic waves to identify the range altitude direction or speed of both moving and fixed objects such as Aircraft, ships Sonar (which started as an Acronym for sound navigation and ranging) is a technique that uses Sound propagation (usually underwater to navigate
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. Scientific modelling is the process of generating abstract, conceptual, Graphical and or mathematical models. Topological relationships between geometric entities traditionally include adjacency (what adjoins what), containment (what encloses what), and proximity (how close something is to something else).
- 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. Neuroscience is a field 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/ Pharmacology of the Brain EEG topography is a Neuroimaging technique in which a large number of EEG Electrodes are placed onto the head following a geometrical array of even-spaced Brain mapping is a set of Neuroscience techniques predicated on the Mapping of (biological quantities or properties onto spatial representations of the (human or In ophthalmology, corneal topography is used as a technique for mapping the surface curvature of the cornea. Ophthalmology is the branch of Medicine which deals with the diseases and surgery of the visual pathways including the Eye, Brain Corneal topography, also known as photokeratoscopy or videokeratography, is a non-invasive Medical imaging technique for mapping the surface The cornea is the transparent front part of the Eye that covers the iris, Pupil, and Anterior chamber.
In human anatomy, topography is superficial human anatomy. Human anatomy, which with physiology and biochemistry is a complementary basic medical science is primarily the scientific study of the morphology of the adult Human body Superficial human anatomy is the part of Human anatomy dealing with Superficial anatomy.
See also
References
- ^ What is topography? - Center for Geographic Information
- ^ Definition from WordNet Search - princeton. See also Topography Starting in Ancient Greece, places have been described in topography ( and an author of such writing has been called a Geomorphology (from Greek: γη ge, "earth" μορφή morfé, "form" and λόγος Logos, "knowledge" edu
- ^ Definition from Federal Citizen Information Center - pueblo. gsa. gov
- ^ Online Etymology Dictionary - etymonline. com
- ^ For example, see the website of the London Topographical Society
- ^ Oxford English Dictionary "Ordnance Survey"
- ^ http://fr.wikipedia.org/wiki/Cartographie#Histoire#France
- ^ Topographical Engineers - History and Personnel
- ^ see for example the publications of National Geographic Trails Illustrated Maps and Delorme products
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