Geography Reference
In-Depth Information
like noise mapping, there might not be a suitable, ready-made color scheme.
Reasons for this are, e.g.:
Ready-made palettes are finite (Wijffelaars et al.
2008
) and color specifications
in
ColorBrewer
should never be treated as ironclad guarantees since color
reproduction, whether on screen or in print, is an inexact science (Harrower
and Brewer
2003
, p. 33).
ColorBrewer
, e.g., offers sequential schemes for up to nine classes, but due to a
low contrast caused by the high number of groups some colors are quite hard to
distinguish, which is especially a problem if the enabling of a correct identifi-
cation of classes is the objective.
Nature of data varies strongly for different applications (Harrower and Brewer
2003
) and can be ordered (ordinal, interval, ratio scale), with a neutral point, or
qualitatively (nominal). Transformed scales, as in our use case logarithmic
scales, are also ordered, but it should be considered that, in this case, arithmetic
operations are not valid and that higher values contribute more to a mean value.
To our knowledge, no guidelines or recommendations are available how this
characteristic can be reflected by color schemes.
Spatial distribution of data can be regular vs. irregular, ordered vs. unordered, or
coarse vs. finely detailed. This can lead to different perceptual effects: “The
more complex the spatial pattern of the maps, the harder it will be to distinguish
slightly different colors” (Harrower and Brewer
2003
, p. 32). Schemes with
lightness steps only, hence, are not appropriate for more than five or six classes.
With the increasing number of devices, and therefore variety of screen sizes,
resolutions, use cases and contexts, color design becomes even more complex. The
major challenge of color design for online maps is that output devices present colors
differently. Consequently colors have to be optimized to suit a variety of devices,
such as computer screens, tablets and smart phones.
Due to this high number of criteria influencing the suitability of schemes,
guidelines are highly dependent on use cases, user tasks, respective data and aims
that are achieved. Starting with fundamentals, such as color perception and scheme
types we thus introduce a framework that concentrates guidelines and combines
them with criteria that facilitate the decision on a suitable color scheme. As a proof
of concept, we give an outline of the guideline
s relevance for the design of
'
noise maps.
Fundamentals of Color Design
Color Perception
How color is perceived depends on many things: “All colors, whether they are seen
as direct or reflected light, are unstable. Every change in light or medium has the
