Choropleth map

Abstract: Graduated point symbols are viewed as an appropriate choice for many thematic maps of data associated with point locations. Areal quantitative data, reported by such enumeration units as countries, are frequently presented with choropleth maps but are also well suited to point symbol representations. Our objective is to provide an ordered set of examples of the many point-symbol forms used on maps by showing symbols with linear, areal, and volumetric scaling on repeated small maps of the same data set. Bivariate point symbols are also demonstrated with emphasis on the distinction between symbols appropriate for comparison (separate symbols) and those appropriate for proportional relationships (segmented symbols). In this paper, the variety of point symbol use is described, organized, and encourage, as is research on these varied symbols and their multivariate forms.

Abstract: Modern computer technology provides cartographers with a host of new display potentialities not possible with traditional printed maps. One of these is sequencing, or the display of map elements in a particular order. This paper evaluates sequencing of choropleth maps via reaction time experiments with human subjects. Informal experiments reveal that subjects favor some form of sequencing, while formal experiments show no significant difference between traditional and sequenced maps for either information acquisition or memory. Since subjects find sequencing appealing and it does not appear to have negative effects on map learning, software developers may wish to consider including it as part of their cartographic display systems. Les cartographes ont acces, grâce a l'actuelle technologie informatique, a un eventail de nouvelles possibilites d'affichage jusque la inaccessibles avec l'impression des cartes traditionnelles. Une de ces possibilites repose sur l'affichage sequentiel d'elements cartographiques...

Abstract: spmap is aimed at visualizing several kinds of spatial data, and is particularly suited for drawing thematic maps and displaying the results of spatial data analyses. Proper specification of spmap options and suboptions, combined with the availability of properly formatted spatial data, allows the user to draw several kinds of maps, including choropleth maps, proportional symbol maps, pin maps, pie chart maps, and noncontiguous area cartograms. spmap completely supersedes its predecessor tmap.