EXPLOREMAP: An Exploration System for Choropleth Maps

Abstract

Software for interactive choropleth mapping typically focuses on design, with the assumption that the resulting map will be used like a traditional paper one. We believe that interactive graphics also should enable users to explore the database underlying a map. In this vein, we have developed software that will permit users to both design a map and explore the underlying database.The exploration component, the raison d'Ctre for the software, includes the following options: Overview, Areas, Reclass, Regions, Tables, and Graphs & Stats. Within Overview, users can display map elements in sequence, any combination of classes, and highlighted subsets of the data. Within Areas, users can determine values associated with areas, compare values for two areas, and determine minimum and maximum values for classes and the entire map. Reclass allows users to reclassify the map data temporarily, thus determining the effect of different classification schemes. The Regions option permits regions to comprise specified areas, while Tables and Graphs & Stats present tabular, graphical, and statistical displays of the data in pop-up windows.The user interface consists of pull-down menus and mouse input, and the software i s compatible with standard IBM VCA graphics hardware. Some potential future enhancements include the display of 256 colors at one time, which will speed display and permit animation; other symbol approaches such as three-D; and links with CIS.People who make maps tend to have a uni-map mentality; they search for the best single symbolization to use on a map. In actuality, a geographical topic may be better illuminated by multi-map display, using more than one form of symbolization for a single data set.More recently, MacEachren and Ganter (1990, 75) expanded o n this theme:Rather than developing expert systems that help find a single optimal map for representing a set of information, we need to develop systems that encourage exploration of multiple perspectives on the same data.In much the same way that Tukey (1977) advocated exploratory methods for aspatial data, cartographers need to develop exploratory methods for spatial data (DiBiase 1990, 14). In this vein, we have developed interactive soft-

Testing the Usability of Interactive Maps in CommonGIS

“…Geographical objects (areas) are rendered in these colors, depending on which intervals their attribute values fit in. When users have an opportunity to interactively change the intervals, classification turns from a pure presentation tool into an instrument for exploratory data analysis (Egbert and Slocum 1992;Andrienko and Andrienko 2001). In CommonGIS, one can dynamically manipulate classes and immediately observe the impact on visual grouping of objects on the map.…”

“…29, No. 4, 2002, pp.325-342 classes in a choropleth map (Egbert and Slocum 1992); • Various interactive devices for controlling map animation (e.g., Edsall and Peuquet 1997;Blok et al 1999;Harrower et al 2000;Slocum et al 2000).…”

GeoJabber: Enabling Geo-Collaborative Visual Analysis

“…It is a fundamental technique in geographic visualization (Mak and Coulson 1991;Egbert and Slocum 1992), in machine learning techniques (Whigham, McKay, and Davis 1992), and many other related fields. In fact, classification is a fundamental scientific Endeavour.…”

Developing Lightweight, Data-Driven Exploratory Geo-Visualization Tools for the Web

“…For more information on non-temporal animation, see: (DiBiase, et al, 1992;Egbert & Slocum, 1992;Peterson, 1993). Building such a sequence is accomplished by dragging variable labels from the list in the left margin to the slots in the "build animation sequence" row.…”