A color scheme for the presentation of sound immission in maps: requirements and principles of design
Monday 1 june, 2015, 15:00 - 15:20
0.3 Copenhagen (49)
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.
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