Slicing OSA-UCS Color Space to Inspire Bivariate Color Scheme Design for Thematic...- Cynthia Brewer

Slicing OSA-UCS Color Space to Inspire Bivariate Color Scheme Design for Thematic Maps
Cynthia Brewer, The Pennsylvania State University
The Optical Society of America Uniform Color Scales (OSA-UCS) has an intriguing structure useful for designing bivariate thematic map color schemes: a cuboctahedral geometry, giving seven cleavage planes and twelve equally distant neighbors for each color. UCS notation is L for lightness, j for yellow (jaune), and g for green. Holding j constant at zero slices from light to dark through greens and reds. An example diagonal slice is L+g=2, giving 56 sample colors ranging from light pink to dark green and flaring to blue-purples on one side and yellows on the other. Choosing nine colors for a 3x3-square bivariate map scheme from these complex cleavage planes provides cartographers with inspiring options, getting past RGB or CMY mixture sets.
This presentation was made at the 2023 annual meeting of the North American Cartographic Information Society (NACIS). For more information on NACIS, check out NACIS.org.