Dorling cartogram

Abstract

W artykule przedstawiono niekonwencjonalne możliwości prezentacji kartograficznej - mapy anamorficzne. Szczegółowo omówiono kartodiagram anamorficzny Dorlinga - metodę dość powszechnie stosowaną w kartografii brytyjskiej, która nie doczekała się jeszcze szerszego opisu w polskiej literaturze kartograficznej. Po krótkim rysie historycznym omówiono założenia metody i sposoby konstrukcji takich kartodiagramów. Pokazano przykłady map opracowanych w programie MapViewer oraz przykłady zastosowania tej metody w Wielkiej Brytanii.The world can be presented on maps in an unusual, unconventional way. The commonly known arrangement of continents or countries may be abandoned in order to expose changeability of a presented phenomenon. Such graphic presentations are referred to as anamorphic maps. Areas of presented units (e.g. countries) are proportional to statistical values, e.g. population, gross national product (fig. 2.). The article presents the assumptions and construction modes of one of anamorphic methods - Dorling cartogram. Examples of maps prepared in MapViewer and examples of application of this method in Great Britain are presented. Method of construction of Dorling cartogram is discussed on the example of maps published in A new social atlas of Britain [A1]. Fig. 6 presents two maps: traditional choropleth map showing the population density of Great Britain by electoral constituency in 1:10 000 000 (fig. 6A) and Dorling cartogram (fig. 6B). Constituencies are presented as circles with the area proportional to population. Location is preserved, but coastal line and borders are distorted. Preparation of such maps without a computer is almost impossible. Figures 8, 9 and 10 show Dorling cartograms of the population of Poland prepared in MapViewer 7 in 2002 and 2007. These maps are difficult to interpret, because readers are not used to seeing the world in unfamiliar shapes. Therefore when preparing them one should attempt to keep the shape and vicinity of particular units. It is advisable to help the users by showing ad-ministrative zones or by attaching a 'traditional' map. Skillful users of anamorphic maps can obtain new information from them