Selecting colour codes for a computer-generated topographic map based on perception experiments and functional requirements

Abstract

This paper describes a series of human factors analyses that guided the selection of chromaticities and luminances for a computer-generated topographic map. By virtue of its impressive computational capabilities, this CRT-displayed digital map will greatly facilitate the navigational accuracy and situational awareness of army helicopter aviators during low level and nap-of-the-earth flight. Colour codes were assigned to the digital map's point, linear and area features according to guidelines derived from four colour naming and two symbol search experiments. The design of each study was structured around the map's functional requirements: the five linear feature colours should have high luminance and support absolute colour identification; the three point symbol colours should be identifiable at small sizes; and the four area colours should minimize colour distortions, with the two terrain colours luminance-shaded to depict elevation information. Within these constraints, the results of the colour naming studies yielded an initial set of map colour codes by identifying the most frequently occurring colour confusions arising from the perceptual distortions of brightness contrast, colour contrast and Gaussian spread. The symbol search studies further refined colour selection by identifying the specific foreground/background colour combinations that hinder search, and by quantifying the conditions under which a colour or monochrome map facilitates symbol search.