A color scheme for the presentation of sound immission in maps: requirements and principles of design
Regular paper
HafenCity University
Monday 1 june, 2015, 15:00 - 15:20
0.3 Copenhagen (49)
Abstract:
Color is the graphical variable most frequently used for the representation
of
different levels of sound immission. If used appropriately it facilitates an
intuitive understanding of the distribution of, e.g., traffic noise in a
city
and thus fosters map usability. However, color design is complex because
color
perception is subjective and context dependent. In practice many
applications
use color in an inappropriate way that hinders map reading or makes it even
impossible for people with color vision deficiencies (e.g., red-green color
blindness). END noise maps are often an example of inappropriate use of
color:
they frequently combine red and green, which cannot be distinguished by 8%
of
male users and use saturated signal colors such as red for the
representation
of values located in the middle of the scale, which therefore are
inadvertently emphasized. Especially for public participation a usable map
and
consequently color design should be prioritized.
Therefore this work presents an alternative color scheme based on
cartographic
principles. A requirements analysis, looking especially at END noise maps,
was
the starting point of the design process. The requirements that were
prioritized were distinguishability for all users; consistency, independent
from object size or object location and that the colors are logically
assignable to the characteristics of the noise data; i.e., that presented
noise levels should not be under- or overestimated, hotspots and silent
areas
should be determined by the users without referring to the map legend and
colors should facilitate an association with the categories of noise levels.
The scheme was thereafter developed in an iterative process including four
user studies with more than 200 participants that ensured that the aims and
requirements were met. The scheme is especially recommended for major roads
in
END noise maps, but can also be used for other types of sound immission.