A typology of operators for maintaining legible map designs at multiple scales

Abstract

The potential for and ubiquity of multiscale mapping is growing as a result ofcontemporary research and development efforts in digital cartography. Past workon multiscale mapping discusses use of the ScaleMaster diagram,a conceptualschematic for organizing, maintaining, and sharing the scale-dependent designspecifications of a multiscale mapping project. Here, we present a typology ofmultiscale mapping operators that can be implemented at the decision pointsidentified within the ScaleMaster diagram in order to maintain legible map designswhen changing scale. The ScaleMaster typology of multiscale mapping operatorsdraws in part on extant literature on generalization, which primarily focusesupon changes to the geometry of map features. We argue that this past work ongeneralization should be appended with other work in map design to generatea comprehensive list of decisions available to a cartographer when changingscale. This extension results in four higher-level categories of multiscale mappingoperators: content, geometry, symbol, and label. In the following, each operator inthe ScaleMaster typology is introduced and explained, with discussion organized according to the four higher-level categories. For each operator, we include aformal definition, a standard two-character code for use in the ScaleMaster diagram, a sample illustration, a description of its use in the cartographicliterature, and our approach to reconciling contradicting uses (whereappropriate). The key contribution of this work is the synthesis and integrationof existing generalization and map design research into a logical framework foruse as a classroom teaching tool, a pragmatic guide for completing multiscalemapping projects, and a conceptual foundation for future scientific research.