Cartographic Visualization

cdv, a cartographic data visualizer, is a piece of demonstration software designed for research and teaching. It uses established symbolism techniques for displaying spatially referenced information, and adds newer dynamic capabilities that are suitable for exploratory spatial data analysis (ESDA). The software takes advantage of the symbolism, dynamism and inherent spatial information afforded by the Tcl/Tk language and comprises interpreted scripts which provide a flexible environment for prototyping and extension. This introduction to the software and approach outlines some of the rationale behind the development and contains an overview of the cartographic and statistical ESDA functionality. The distributed scripts produce concurrent linked views of enumerated data sets. Views are available for statistical and geographic visualization of univariate, bivariate and multivariate distributions. These include dotplots, scatterplots, polygon maps, population cartograms and parallel co-ordinates plots. Each view is extremely dynamic so that transient maps can be produced to highlight specific cases and to focus on points of interest to suit the researcher. The ideas are applied to procedures for determining locality and assessing the characteristics of local variation, and some examples of dynamic graphical local indicators are provided. The examples and images provide a flavour of the approach and the dynamic and flexible nature of the software. One of the advantages of the approach is that, as the software is free and accessible on the Internet, the author is not restricted to static black-and-white graphics for communicating dynamic colourful ideas. Larger colour versions of the images can be downloaded to support the paper.