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

The potential for and ubiquity of multiscale mapping is growing as a result of contemporary research and development efforts in digital cartography. Past work on multiscale mapping discusses use of the ScaleMaster diagram, a conceptual schematic for organizing, maintaining, and sharing the scale-dependent design specifications of a multiscale mapping project. Here, we present a typology of multiscale mapping operators that can be implemented at the decision points identified within the ScaleMaster diagram in order to maintain legible map designs when changing scale. The ScaleMaster typology of multiscale mapping operators draws in part on extant literature on generalization, which primarily focuses upon changes to the geometry of map features. We argue that this past work on generalization should be appended with other work in map design to generate a comprehensive list of decisions available to a cartographer when changing scale. This extension results in four higher-level categories of multiscale mapping operators: content, geometry, symbol, and label. In the following, each operator in the ScaleMaster typology is introduced and explained, with discussion organized.