Showing papers on "Choropleth map published in 1994"
01 Oct 1994-Cartographica: The International Journal for Geographic Information and Geovisualization
TL;DR: This paper examined the visual search process used by map readers when interacting with bivariate choropleth maps, and assessed the potential of one of psychology's models, Attentional Engagement Theory, for explaining that process.
Abstract: Searching is a fundamental but complex task in the map-reading process. Several psychologists have explored the role of visual search in cognition, and have proposed a number of models that may offer cartographers a basis for understanding how people search for specific map information. The purpose of this research was to examine the visual search process used by map readers when interacting with bivariate choropleth maps, and to assess the potential of one of psychology's models, Attentional Engagement Theory, for explaining that process. The study employed a standard search task that determined the efficiency of the search process by having subjects search for target colours among non-target colours across a map. An analysis of reaction times showed that the following variables affected search efficiency: target colour, the total number of objects on the map, and similarity of the target colour to all other non-target colours on the map.
18 citations
TL;DR: It is concluded that dasymetric and isarithmic maps are a desirable alternative and can be relatively easily generated using satellite imagery in a geographical information system.
Abstract: The spatially discontinuous choropleth map is a poor representation of the underlying continuous distribution of population density. A possible alternative is to derive dasymetric maps at a fine spatial resolution by making use of satellite imagery in a geographical information system. However, there are cartographic problems when these maps are displayed and further processing is needed in order to obtain approximations to a continuous density surface. Isarithmic maps of these density surfaces retain a high degree of spatial accuracy while providing pleasing and highly adaptable presentations.The methods used to generate dasymetric and isarithmic maps are readily implemented in most raster based geographical information systems. For example, the classification of remotely sensed imagery, the subsequent processing and integration of data, and most of the cartographic display, were all undertaken in this work using the low cost IDRISI GIS that operates on standard IBM PC compatible hardware.
TL;DR: In this article, three methods to predict the sand and clay content of Bas-Zaire using a reconnaissance soil map and 151 soil profiles are compared and a cross-validation showed that the combination method produced the most precise predictions with an acceptably small bias.