A Change of Theme: The Role of Generalization in Thematic Mapping

Abstract

Cartographic generalization research has focused almost exclusively in recent years on topographic mapping, and has thereby gained an incorrect reputation for having to do only with reference or positional data. The generalization research community needs to broaden its scope to include thematic cartography and geovisualization. Generalization is not new to these areas of cartography, and has in fact always been involved in thematic geographic visualization, despite rarely being acknowledged. We illustrate this involvement with several examples of famous, public-audience thematic maps, noting the generalization procedures involved in drawing each, both across their basemap and thematic layers. We also consider, for each map example we note, which generalization operators were crucial to the formation of the map’s thematic message. The many incremental gains made by the cartographic generalization research community while treating reference data can be brought to bear on thematic cartography in the same way they were used implicitly on the well-known thematic maps we highlight here as examples.

Analysis of Articles on Labioplasty with Science Mapping Technique

“…Balloon size is proportional to cluster word occurrences. The position of the balloon is adjusted according to the centrality and density (15). Thematic Map consists of four themes: Emerging Theme, Highly developed and Isolated Theme, Motor Theme and Basic Theme.…”

Spatial Monitoring and Classifying of Urban Deterioration in the Egyptian Cities Using Geographic Information System (GIS) Approach: A Case Study of Mansoura City, Egypt

“…These dimensions were selected in accordance with the average lengths of residential blocks in the Mansoura city. In addition, the hexagonal shape has the advantage of having equal diameters, and therefore, it was chosen as one of the best geometrical shapes to express the phenomena [48][49][50]. This also helps to increase the accuracy of the spatial monitoring of urban elements, by measuring the percentage of concentration of those elements within each cell, like most urban indicators as shown in Table 2.…”

Heat Maps: Perfect Maps for Quick Reading? Comparing Usability of Heat Maps with Different Levels of Generalization

“…There can be no effective thematic map without simplifying input data and cartographically refining them. Raposo et al [26] underline the role of generalization in thematic mapping by stating that "generalization is ubiquitous and critical in all cartography, and by corollary that it is an important aspect of the highly popular thematic mapping currently capturing public and otherwise non-cartographer attention". The authors also applied the typology of generalization operators (for content, geometry, symbol and label) proposed by Roth, Brewer, and Stryker [27].…”

“…Therefore, in this study, we compared four heat maps with different levels of generalization-that is, a different kernel radius. The aforesaid level of generalization is crucial for thematic maps [25,26]; hence, we wanted to provide empirical evidence of if, and how, it differs in terms of usability metrics. We investigated whether heat maps are a good solution for making small-scale maps for quick reading, and if they allow young users to retrieve quantitative values quickly and correctly.…”

“…As generalization is substantial for thematic mapping [25,26], a significant amount of research on this subject could be expected. However, most papers on the topic of generalization incorporate theory or describe self-analysis by the authors [39,40].…”