5.1 The range of visual resources
Cartographers can apply these resources to points, lines, and areas in a variety of ways.
Each of these resources can be used individually to draw attention to map features, or they may be used in combination. Sometimes cartographers deploy several of these resources simultaneously to stress particularly important information or to improve its legibility.
5.2 Strategies of symbolization
Ratio data is information that, like interval data, can be arranged along a scale but, in addition, the scale begins at a non-arbitrary zero point. At the zero point, no features are present. The operations of multiplication and division can be employed with ratio data to consider proportions and magnitudes. Elevation above sea level, precipitation, and population are all examples of ratio data.
5.3 Typography and lettering
Concise, carefully formulated captions and annotations make a tremendous difference to a map. Compare:
Bertin's semiotic resources apply to text just as they do to points,
lines, and areas. However, with respect to text, some of these resources
are given special names. Font refers to the shape and pattern of letters.
Hundreds of fonts have been created since the invention of the printing
press and are available using automated systems. Fonts are often grouped
into several broad categories. A distinction is made between
fonts, as well as between Roman and Italic fonts. The weight
of text is classified as , ,
fonts can be scanned more rapidly by most readers, although less information
seems to be retained than would be the case if the same text was displayed
font. Italic fonts are used for the titles of books and journals and for
some proper names. Since it was impossible to print italic characters with
was used to indicate the placement of italic characters. It is no longer
necessary to employ this convention with automated systems capable of printing
italic characters. Traditionally the size of lettering was measured in
picas or point size. Increasingly, automated systems measure size using
conventional units such as inches and millimeters. The horizontal and vertical
distances between lettering are traditionally referred to as leading
, but increasingly today as inter-character and inter-line spacing.
Although automated systems offer a wealth of fonts and sizes, good practice
dictates that these resources be used sparingly. Too many fonts (and sizes)
can potentially confuse the reader. Traditionally, typographers try to
use no more than four fonts or font sizes on a given page of print. Apply
the same principle to your maps. Use different fonts and sizes only when
you have a compelling reason to do so.
Lettering is also distinguished by case: UPPER CASE, lower case, and Mixed Case.
If you consider professionally produced maps, you find that font, size, and case are used very carefully to encode text. In effect, the text is used to group information into useful categories that reflect the theme of the map.
Special attention must be paid to the orientation of text with respect to the features being labeled. In this respect, text can be used as an important cue to different map features.
The arrangement of letters can also be used to convey quite subtle distinctions. For example, in the following map, lettering pertinent the map theme is aligned with the map frame whereas lettering that describes the background features is aligned with the graticule.
Quite apart from labeling features, text is used for convey other information about the map--sources, date, methods of compilation, projection, and cartographer. This ancillary information is usually placed in a subordinate position within the frame of the map. However, the readability of your map will be improved if you position this text in relation to the major map elements. That is, your map can be composed with implicit margins and tabs that can be used as a means of alignment for subsidiary text.
The key to resolving foreground-background relationships is to use color, value, and patterning to "raise" some map features into the foreground. In some respects this is like using color, value, and patterning to produce a sort of three-dimensional effect in which certain key features appear to rise off the map's two-dimensional surface. In fact, these resources can be used to create a sort of three-dimensional visual hierarchy.
This idea can be put to practical use in a wide range of situations where the reader would otherwise have difficulty sorting out information displayed on a map.
Understanding the dynamics of foreground-background relationships can also help resolve certain ambiguities that sometimes arise in mapmaking. Consider the following example:
Depending the map and mapping system you employ, any of the options might be used either singly or in combination.
5.5 Highlighting the theme
Bertin, Jacque. 1983. Semiology of Graphics: Diagrams, Networks, Maps. Translated by W.J. Berg. Madison: University of Wisconsin Press.
Board, C. and Taylor, R.M. 1985. Perception and maps: Human factors in map design and interpretation. Transactions of the Institute of British Geographers New Series 2: 19-36.
Cleveland, William S. and McGill, Robert. 1985. Graphical perception
and graphical methods for analyzing scientific data. Science 229:
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