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MaP Design
that are separate from one another. In Figure 4.8 the two squares are the same gray,
but when they are placed on darker or lighter shades, they look different. In addition,
although it is easy through software to create 10 shades of gray, the human eye can-
not distinguish that many shades easily. The gray scale in Figure 4.4 shows 10 light-
ness steps, but adjoining steps are not easy to differentiate from one another. This is
one reason that most quantitative black-and-white maps use only five or six shades.
Because lightness steps usually imply quantitative value, using different shades
of gray for different qualitative categories is misleading. In such cases, patterns can
be used and the orientation of lines can be varied (although this can create an “old-
fashioned” look). Pictorial area symbols can also be used, such as the grassland and
tree patterns in Figure 4.9. These visual variables are described in Chapter 7, on
symbolization.
If one knows at the beginning of the design process that the map will be limited
to black and white, it is easiest to simply design in those neutrals. However, if the
map may be viewed in both black and white and color, then colors that reproduce
in distinct shades of gray must be chosen. This requires some care. For example, if
a color map might be printed in both color and black and white for different pur-
poses, or if it is likely that black-and-white copies will be made on a copy machine,
for example, handouts of a PowerPoint presentation, this must be considered before
choosing colors. The ramp (shades of gray) may not be a smooth gradation or the