Visual Variables
Robert E. Roth · International Encyclopedia of Geography · 2017
The visual variables describe the graphic dimensions across which a map or other visualization can be varied to encode information. Twelve visual variables are introduced and discussed: (i) location, (ii) size, (iii) shape, (iv) orientation, (v) color hue, (vi) color value, (vii) texture, (viii) color saturation, (ix) arrangement, (x) crispness, (xi) resolution, and (xii) transparency. The perceptual basis of the visual variables is then summarized, which informs use of the visual variables for univariate and bivariate mapping.