Triangulated irregular network
2857072
221284779
2008-06-23T21:17:55Z
DumZiBoT
6085301
robot Adding: [[it:Vertice geodetico]]
A '''triangulated irregular network''' ('''TIN''') is a digital [[data structure]] used in a [[geographic information system]] (GIS) for the representation of a [[surface]]. A TIN is a [[Array|vector]] based representation of the physical land surface or sea bottom, made up of irregularly distributed [[vertex (geometry)|nodes]] and lines with [[dimension|three dimensional]] [[coordinates]] (x,y, and z) that are arranged in a network of nonoverlapping triangles. TINs are often derived from the elevation data of a [[raster|rasterized]] [[digital elevation model]] (DEM). An advantage of using a TIN over a DEM in mapping and analysis is that the points of a TIN are distributed variably based on an [[algorithm]] that determines which points are most necessary to an accurate representation of the terrain. Data input is therefore flexible and fewer points need to be stored than in a DEM with regularly distributed points. While a TIN may be less suited than a DEM raster for certain kinds of GIS applications, such as analysis of a surface's [[slope]] and [[aspect (geography)|aspect]], TINs have the advantage of being able to portray terrain in three dimensions.
A TIN comprises a triangular network of vertices, known as mass points, with associated [[coordinates]] in three [[dimensions]] connected by edges to form a triangular [[tessellation]]. Three-dimensional visualizations are readily created by rendering of the triangular facets. In regions where there is little variation in surface height, the points may be widely spaced whereas in areas of more intense variation in height the point density is increased.
A TIN is typically based on a [[Delaunay triangulation]] but its utility will be limited by the selection of input data points: well-chosen points will be located so as to capture significant changes in surface form, such as [[topographical summit]]s, breaks of slope, ridges, valley floors, pits and cols.
Although usually associated with 3-dimensional data (x,y, and z) and topography, TINs are also useful for the description and analysis of horizontal (x and y) distributions and relationships.
==Related software==
*The first triangulated irregular network program for GIS was written by Randolph Franklin at [[Simon Fraser University]] in [[1973]].<ref>{{cite web |title=Research - Triangulated Irregular Network |accessdate=2007-07-26 |url=http://www.ecse.rpi.edu/Homepages/wrf/pmwiki/Research/TriangulatedIrregularNetwork }}</ref>..
==References==
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[[Category:Geography]]
[[Category:Cartography]]
[[de:Unregelmäßiges Dreiecksnetz]]
[[es:Red irregular de triángulos]]
[[it:Vertice geodetico]]
[[ja:TIN]]
[[pl:TIN]]