Created Date: 10/20/2011 3:57:17 PM Thiessen polygons (also known as Dirichlet tessella- tions or Voronoi diagrams) de fine the area of influence of each focal point (e.g. nest-site) by a polygon encom- passing the area closer to the The Thiessen polygon is a commonly used methodlogy for computing the mean areal precipitation for a catchment from raingauge observations which was presented by A.H. Thiessen (1911).The Thiessen method is based on the assumption that measured amounts at any station can be applied halfway to the next station in any direction, which means that for any point rainfall is equal to the observed THIESSEN POLYGON METHOD Advantage quick if multiple storm (uses fixedsub-areas) PROCEDURES :-2nd APPROACH. Cont ' MEAN AREAL PRECIPITATION 1. CONNECT each precipitation STATION with STRAIGHT lines 2nd APPROACH. Cont ' MEAN AREAL PRECIPITATION 2. Thiessen's Polygon:The Method. Locate all rainfall stations on a base map and record the rainfall amount. Connect each station by straight lines with the several nearest stations to form a series of triangles. Erect perpendicular bisectors on each of these lines and extend them to the intersect with other bisectors, thus forming a series of Thiessen polygons (otherwise known as Voronoi polygons or Voronoi diagrams), are an essential method for the analysis of proximity and neighborhood. Thiessen polygons (cf. figure below on the right side) are used to allocate space to the nearest point feature. It defines an area around a point, where every location is nearer to this point than Thiessen polygons are generated from a set of sample points such that each polygon defines an area of influence around its sample point, so that any location inside the polygon is closer to that point than any of the other sample points. Thiessen polygons (also called Voronoi Diagrams) can be used to show catchment areas for a group of facilities. Thiessen polygon method. A method of assigning areal significance to point rainfall values. Perpendicular bisectors are constructed to the lines joining each measuring station with those immediately surrounding it. These bisectors form a series of polygons, each polygon containing one station. The value of precipitation measured at a station is A more practical application is found in the work by Alfred H. Thiessen, an American meteorologist, after whom the term "Thiessen polygon" was created. He used Thiessen/Voronoi polygons to obtain an improved estimation of regional rainfall averages (Thiessen 1911), which is one of the first examples of using the Voronoi diagram for spatial This video was created for classes in the department of Engineering and Computer Science at NCSSM.NCSSM, a publicly funded high school in North Carolina, pro A quick intro on breaking up an area using the Thiessen Polygon method. It's not pretty, but it is relatively straightforward.