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Randolph Franklin, under the direction of David Douglas and Thomas Peucker (Poiker), at Simon Fraser University in 1973. The first triangulated irregular network program for GIS was written by W. The TIN model was developed in the early 1970s as a simple way to build a surface from a set of irregularly spaced points. Constrained Delaunay triangulations are also useful for minimizing the size of a TIN, since they have fewer nodes and triangles where breaklines are not densified. A constrained Delaunay triangulation can be considered when you need to explicitly define certain edges that are guaranteed not to be modified (that is, split into multiple edges) by the triangulator. Additionally, natural neighbor interpolation and Thiessen (Voronoi) polygon generation can only be performed on Delaunay conforming triangulations. This is because the resulting TINs are likely to contain fewer long, skinny triangles, which are undesirable for surface analysis. Delaunay conforming triangulations are recommended over constrained triangulations. TIN are based on a Delaunay triangulation or constrained Delaunay. While a TIN may be considered less suited than a raster DEM for certain kinds of GIS applications, such as analysis of a surface's slope and aspect, it is often used in CAD to create contour lines. Data input is therefore flexible and fewer points need to be stored than in a raster DEM, with regularly distributed points.
An advantage of using a TIN over a rasterized digital elevation model (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 create an accurate representation of the terrain. 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.Ī TIN used to represent terrain is often called a digital elevation model (DEM), which can be further used to produce digital surface models (DSM) or digital terrain models (DTM). Three-dimensional visualizations are readily created by rendering of the triangular facets. Associated with three-dimensional ( x, y, z ) that are arranged in a network of non-overlapping triangles.Ī 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. The vertices of these triangles are created from field recorded spot elevations through a variety of means including surveying through conventional techniques, Global Positioning System Real-Time Kinematic (GPS RTK), photogrammetry, or some other means. In computer graphics, a triangulated irregular network ( TIN) is a representation of a continuous surface consisting entirely of triangular facets (a triangle mesh), used mainly as Discrete Global Grid in primary elevation modeling.
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