Showing papers on "Choropleth map published in 1984"
1 Jan 1984
TL;DR: Applications of a computer program, BICHOR, designed to produce unclassed bivariate choropleth maps interactively on a line plotter or CRT are discussed.
Abstract: Many cartographers subscribe to the view that unclassed choropleth maps and multivariate choropleth maps exceed map readers' abilities to process visual information. This paper examines recent evidence which controverts both of these beliefs and discusses applications of a computer program, BICHOR, designed to produce unclassed bivariate choropleth maps interactively on a line plotter or CRT. The maps utilize crossed-line symbolism and putatively overcome both the quantization error inherent in conventionally classed choroplethic displays and the perceptual difficulties associated with color-encoding schemes used for earlier bivariate maps.
10 citations
TL;DR: An alternative approach to encoding choropleth maps where the neighbourhood relationships are encoded using the node as the organisational unit, which should permit the development of general purpose display algorithms.
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.
2 citations
TL;DR: In this article, a method has been developed for selecting intervals between successive observations on transects such that the risk of omitting boundaries remains constant and in this sense the method is optimal.
1 citations
1 Sep 1984
TL;DR: In this article, a method of relatively inexpensive production of several hundred or even several thousand choropleth maps of census data involving the joint application of computational and microfiche technologies is described.
Abstract: A method of relatively inexpensive production of several hundred or even several thousand choropleth maps of census data involving the joint application of computational and microfiche technologies is described. The method involves three stages: data preparation, classification and mapping. These are exemplified by the use of data from the 1981 Australian Census of Population and Housing. The same method can be applied to any region in the world for which census data are available. In the not too distant future it is envisaged that students, teachers, planners and researchers around the world will use microfiche which present choropleth maps of census data—a new and an important infonnation resource.
TL;DR: This paper studied the methods by which map readers interpret the spatial variation in the relationship between the two variables mapped within each choropleth zone, using two different map designs, the United States Bureau of the Census colour-coded map and the continuous tone map, subjects were to form regions of contiguous zones based on perceived relationships between the variables.
Abstract: The major function of a two-variable map is to depict the spatial variation in the relationship between the two variables mapped. This research studies the methods by which map readers interpret this relationship within each choropleth zone. Using two different map designs, the United States Bureau of the Census colour-coded map, and the continuous tone map, subjects were to form regions of contiguous zones based on perceived relationships between the variables. Both map reading groups performed the task satisfactorily; their methods of solution were similar, and the regions selected were very similar. Each map design produced reasonable results, and each showed some limitations.