A Triangulation Data Structure for Choropleth Base Maps
Author: Cromley, Robert G.
Source: Cartographic Journal, The, Volume 21, Number 1, June 1984 , pp. 19-22(4)
Publisher: Maney Publishing
Abstract:Most early methods for encoding choropleth maps have used the region or individual data zone as the organisational unit for storing the locational and topological properties of the map. This paper presents an alternative approach to encoding choropleth maps where the neighbourhood relationships are encoded using the node as the organisational unit. The direct relationship between choropleth base maps and a Thiessen diagram enables the same triangular data structures developed to store a Delauney triangulation to be used to store a choropleth map. Individual polygons are retrieved by enumerating the sequence of nodes that comprise their outline in a clockwise manner. The commonality among the data structures for storing different types of maps should permit the development of general purpose display algorithms.
Document Type: Research Article
Publication date: 1984-06-01