Mapping the Universe - Mapping Scientific Frontiers: The Quest for Knowledge Visualization - page 51

Orientation of the textural elements is more important in figure development than is
the positioning of the elements. The cartographic literature also provides evidence
that texture and texture discrimination lead to the emergence of figures.
Adding clear edges to figural objects can produce a strong figure in two-
dimensional visual experience. Conversely, reducing edge definition can weaken
figural dominance. There are many ways to form edges, for example, using contrasts
of brightness, reflection, or texture. If the cartographer overlooks the role of figures
and grounds, the resultant maps are likely to be very confusing.
A significant geographical clue is the differentiation between land and water,
if the mapped area contains both. This distinction has been suggested as the first
important process in thematic map reading. Maps that present confusing land-water
forms deter the efficient and unambiguous communication of ideas. Land-water
differentiation usually aims to cause land areas to be perceived as figures and water
areas as ground. In unusual cases, water areas are the focal point of the map and
would therefore be given graphic treatment to cause them to appear as figures.
Cartographers have developed comprehensive guidelines for using letters in a
map. Here are four golden rules:
1. Legibility
2. Harmony
3. Suitability of reproduction
4. Economy and ease of execution
Good lettering design on the map can be achieved by contrast of capitals and
lowercase. A map that contains only one form or the other is exceptionally dull and
usually indicates a lack of planning. In general, capitals are used to label larger
features such as countries, oceans, and continents, and important items such as
large cities, national capitals, and perhaps mountain ranges. Smaller towns and less
important features may be labeled in lower case with initial capitals.
Careful lettering placement enhances the appearance of the map. There are
several conventions, supported by a few experimental studies. Most professional
cartographers agree that point symbols should be labeled with letters set solid (no
letter spacing). Upper right positioning of a label to a point symbol is usually
recommended.
The visual hierarchy, also known as organizational hierarchy, is the intellectual
plan for the map and the eventual graphic solution that satisfied the plan. The
cartographer sorts through the components of the map to determine the relative
intellectual importance of each, then seeks a visual solution that will cast each
component in a manner compatible with its position along the intellectual spectrum.
Objects that are important intellectually are rendered so that they are visually
dominant within the map frame (See Fig. 2.3 ).
The planning of visual hierarchy must suit the purpose of the map. For example,
water is ordinarily placed beneath the land in the order. Fundamental perceptual
organization of the two-dimensional visual field is based on figure and ground.
The figure-ground phenomenon is often considered to be one of the most primitive