Using Color Harmony to Select the Geographical Map Colors

Abstract

The perception of information from geographical maps should be comfortable and free from errors. Therefore, a technically validated choice of adjacent colors in different maps is an important and relevant issue. An analysis of published sources did not make it possible to identify quantitative lighting requirements for the colors of geographical maps. This circumstance prompted the authors to use the results from studies on selecting harmonious and well-distinguishable adjacent colors as applied to geographical maps and to calculate the color thresholds between these colors in a uniform-chromaticity system. Geographical maps with harmonious colors and with poor color solutions have been found and analyzed. The selected combinations were subjected to computational studies using Professor A.B. Matveev’s uniform-chromaticity system along with subjective experiments on evaluating well-distinguishable and harmonious adjacent colors using the quality scale of the method of categories on the laptop screen. The estimations of observers and the calculation results were used to determine the average rating grades of color combinations characterizing the degree of harmony between the adjacent colors and color contrasts. As a result, it was suggested to use color combinations in geographical maps with scores above 3.5 points (i.e., a combination of colors assessed, in terms of their harmony, above the boundary between the categories "satisfactory" and "good"). It has also been determined that the color contrast of 15 thresholds is positively discernible, although it follows from the comments of individual observers that such a difference of colors in their combination may be insufficient and still difficult to perceive in reading the maps. A conclusion has been drawn that it is more appropriate to use combinations with a color contrast of at least 20 thresholds in geographical maps. Specific fragments of geographical maps containing poorly matched colors are pointed out, for which more harmonious colors were suggested (by 1.2 points on average for all combinations considered in the article), as well as comfortable ones (with a color contrast of more than 28 thresholds) for the perception of observers with the measured chromaticity and brightness coordinates.