156 sYMBOLizaTiOn
gled mass; if they are colored a solid hue, individual circles are difficult to distinguish
and may be “blotted out” entirely. Solutions to this problem are
haloing and using
transparent circles. Haloing involves surrounding the circles with white or a lighter
tone. Transparent circles appear to be made of translucent or transparent layers so
that all of the circles can be seen. It is possible to draw circles that have a fill color,
gray tone, or pattern, but no outline. This tends to be a matter of personal prefer-
ence; it is not a subject that has been given much attention. To some, however, the
lack of an outline looks unfinished. Color and tonal choices are made according to
the guidelines in Chapter 4.
BAY AREA POPULATION
BY COUNTY
100,000-500,000
500,001-1,000,000
1,000,001-2,000,000
TOTAL POPULATION
fIgURe 8.12.
Redundancy with lightness and size. Some cartographers feel this reinforces
the
information, others believe it is confusing.
fIgURe 8.13.
When circles overlap they can be confusing; filling with masks and halos can
make the information more clear.
Designing and Choosing symbols 157
legends for Proportional and graduated symbols
In part the decision for type of legend is determined by the amount of space available,
but it is also governed by the type of proportional figure and the capabilities of the
software. Choices range from a simple statement to a complete range of circle sizes.
Figure 8.14 shows a variety of legend types. The nested type, Figure 8.14a, conserves
space; the style in Figure 8.14b allows the reader to estimate sizes for intermediate
circles not shown on the legend; and the style in Figure 8.14c, while using more space,
allows display of all circles for a range-graded map.
