2.5. Presentation of Language Data on Maps

Map data can be presented on maps in a number of ways. A particular language feature can, for instance, be visualized at particular geographic points, lists of connected points, and/or particular regions.

Point

In general, a point on the map is defined by a geo-coordinate, i.e. a latitude-longitude pair. At a higher abstraction level, a point may also represent a particular address. For example, the address “Markusstraße 3, Bamberg, Germany” can be presented as a point, defined by the latitude-longitude pair (49.895265, 10.884404).

Line

A line or path is defined as a list of connected points. If a certain feature can be associated with a set of connected points, the line representation is the most appropriate choice. Such lines are used quite frequently to map weather data, e.g. temperature, humidity etc.

Shape

A shape is a list of connected points where the last point is the same as the first, what results in it enclosing a geographic area. Shapes can be of any arbitrary form, in addition to regular forms like triangle, quadrangle, circle, ellipse etc. Since shapes imply geographic regions, they are often used in maps that present particular features on the region-basis. For example, the presentation of population density normalized over countries can be presented in maps, where country boundaries are rendered as shapes with different colors for different population densities.

Raster and Vector Map Displays

In order to present map data, two kinds of displays can be used: raster map display and vector map display. A raster map display breaks the map region into identical units, e.g. pixels, that completely occupy the map region (cf Kretzschmar 2013). Afterwards, each piece of information is presented as occupying one or multiple units on the map. A vector map display uses points, lines and shapes of arbitrary sizes, instead of breaking the map region into small units.

Base Map

A base map provides only the essential location outlines on which other information can be superimposed. ESRI provides two definitions for the term “base map”. They define it as a “map depicting background reference information such as landforms, roads, landmarks, and political boundaries, onto which other thematic information is placed. A base map is used for locational reference and often includes a geodetic control network as part of its structure.” The second definition is not that general but rather focused on the Graphical Information System (GIS). It defines a base map as a “map to which GIS data layers are registered and rescaled.” Base maps are used to create dynamic maps, where different sets of map data can be added or removed to or from the presentation dynamically.

Layer

Nicholas Chrisman defines layer as “a collection of related geographic data. In some cases, a layer may contain a coverage, hence provide an attribute value at all locations. In some cases, a layer simply collects all features with a common graphic symbolism, roads, national parks, political boundaries, and rivers might be considered different layers.” The layering technique is very essential, because it improves the visualization of map data considerably. Maps can be made interactive to enable users to select only the layers for the set of data they are interested in. Thus, they can extract the information they are looking for instead of being over-burdened by too much, often unnecessary information, for their purposes.

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