A comparative study of existing multi-scale maps: what content at which scale?

Abstract

GIScience 2016 Short Paper Proceedings A comparative study of existing multi-scale maps: what content at which scale? Marion Dumont 1 , Guillaume Touya 1 , Cecile Duchene 1 Laboratoire COGIT, IGN, 73 avenue de Paris, 94165 Saint-Mande Cedex, France Email: {marion.dumont; guillaume.touya; cecile.duchene}@ign.fr Abstract This paper presents a comparative study of existing topographic multi-scale maps, regarding relations between display scale and level of abstraction (LoA) of the map content. The general trends in zoom levels distribution across scale and the original patterns in transitions between LoAs are especially highlighted. 1. Objectives Multi-scale maps are displayed in mapping applications, i.e. websites where a multi-scale navigation in topographic maps is available. Each producer chooses the display scale and the map content for each zoom level. When users zoom in or out, they actually change the displayed zoom level in the multi-scale map. In some multi-scale maps, the difference of content between two consecutive zoom levels can be strong, partly due to the change of scale. Mackaness (2007) explains that map scale also relates to a level of abstraction (LoA) of the map. It represents the amount of complexity of the map content: which geographic phenomena are represented, and with how much detail? Due to these changes, we believe that general users may have difficulties to recognize the depicted location or the different representations of a same object across zoom levels. Figure 1. Zoom levels of this multi-scale map (IGN France) present large differences To build knowledge from multi-scale maps specifications, we study sixteen existing multi-scale maps, provided by national mapping agencies, private companies or collaborative communities. In this paper, we study the correlation between zoom levels, display scale and level of abstraction of the map content, in general (section 2), then focusing on a particular geographic theme: the settlement areas (section 3). 2. How Zoom Levels, Display Scale and Map Content Are Related? To compare the distribution of zoom levels across scale between multi-scale maps, we first need to define and measure the scale of each zoom level. Besides, most national mapping agencies build their multi-scale map from their topographic paper map series, where each map is designed for a specific printing scale. This map can then be displayed at one or more