This study analyzed 16 multi-scale maps from national mapping agencies and private producers to identify common practices for representing map content across zoom levels. The analysis found that individual buildings and urban areas are commonly represented across a similar scale range. It also identified the levels of abstraction (LoA) - simplification, selection, aggregation, and typification - used to represent settlements at different zoom levels. Guidelines on the relations between definition scales, used for initial map production, and display scales, used for online viewing, are proposed to avoid readability issues. The authors plan to use mixed representations and add intermediate levels to existing maps to smooth content changes between zoom levels and improve user navigation.

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Acknowledgments
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References
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