Nederlands | MAND atlas ↓ cartography | GTRP transcriptions

Cartography: typology

Next follows a shortened version of the Dutch text.

Maps can be typified in several ways. First of all there is a distinction between maps using symbols versus maps using colored areas (choropleth maps). Next is a distinction between maps showing all places where some specific phenomenon has been found (qualitative maps) versus maps showing per place how much of this phenomenon has been attested or how many times (quantitative maps). A map is characterized, of course, by both distinctions at one and the same time. A caveat should be made with choropleth maps: the shape of colored areas is most often quite unrelated to the map's main theme. So the impression of expansion or of intensity of the mapped phenomenon, suggested by the size or by the color saturation of the pre-fixed areas, often does not reflect actuality or expectation. Boundaries of areas have no meaning when their shape has been determined in a way which is unrelated to the mapped data.	More in new window: symbol map line map isoglos choropleth more on zip codes frequency by symbols frequency by coloring arrow map Wattel map more on Wattel applications more on symbols map as starting point
Expectations of expansion or of intensity may be calculated though by statistical means; when such calculations include geographical variables to determine the shape of areas then we have a map where boudaries indeed bear meaning. 'Kriging' is one such method while the Wattel application used at the Meertens Institute uses another but similar approach. The idea behind these statistical maps is that the occurence of a phenomenon at one place influences the chance of occurence of the same phenomenon at another place. Before the advent of computers maps often served as databases: they showed 'what could where be found' but did so for many different phenomena at the same time. Computers make it easy to switch phenomena on and off; in this way themes can be compared while at the same time respecting the clarity of the map. Some more on graphical means:
symbol map: symbols represent phenomena; symbols may just overlap or symbols may reflect overlapping by the way they are constructed with each constructing element (or the absence of it) being assigned to one of the mapped phenomena. Think of shape, filling, grain, size, orientation, markedness. By focussing on one element one 'highlights' the appropriate phenomenon. The clarity of the map may be better served this way than having symbols stacked upon each other. A symbol may just represent a qualitative phenomenon but it may also represent a class of frequencies or other type of measurements. line maps: having established a symbol map first one may next draw a line between two places showing each a different symbol. Same symbols may group in single areas. Lines may cross when different phenomena are mapped together. choropleth maps: quite the same as line maps the difference being the coloring of areas. Coloring allows some gradient to be expressed by, for example, shading. Line maps can also express gradience, for example by the use of different types of lines. Meaninglessness of borders of colored areas is even greater when pre-fixed areas are used which are based on other (types of) knowledge. E.g. zip code areas or census districts. When formulas are used to calculate the shapes of areas on the basis of the mapped data these area borders become meaningful. For convenience sake we refer to the (English) article on the reasoning behind the → Wattel-application. A special category of maps consists of maps made by drawing arrows reaching from one place to another place. E.g. people may indicate which places they think of as speaking related dialects; by their number and the number of targeted locations arrows may seem to shape areas (or, reversely stated, blank areas may indicate borders). It is recommended to keep maps clear and effective - one should therefore limit the number and types of data expressed on the map. Once again, computers may be quite helpful in manipulating maps.	symbol map line map isoglos choropleth frequency by symbols frequency by coloring arrow map more on symbols Wattel map more on zip codes top
Visual answers As noted before a map should immediately convey its message to the beholder. "Nur leer scheinende Karten prägen sich dem Gedächtnisse ein", is a saying attributed to Alexander von Humboldt. Computers seem the way to comply with this aphorism.
The Frenchman Jacques Bertin wrote a masterpiece on the conveying of information by means of graphics, his Sémiologie graphique of 1967. Though nowadays hard to find the book has had its impact on the development of infographics, including maps. An English translation exits. The 'visual answers' Bertin set out to find require respect of limitations of visual language. His design principles are now within reach for everyone by the advent of desktop computers.	Sémiologie graphique Semiology of Graphics more on symbols top
A modest attempt at producing an ideal atlas has been made by the Morphology Atlas of Dutch Dialects in combining printed maps and manipulatable maps at the same time and providing for non-linguistic types of information as well. In this way a map will provide, as envisioned by the famous Dutch atlas designer Bos, "materials to digest and opportunity for reflection", since, to paraphrase Bos, "knowledge is in the eye of the beholder".	More in same window: MAND atlas applications map as starting point a history of the Bos atlas

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