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Adjacent polygons must have distinct random color

June 27 2008 | 0 comments
Categories: ArcGIS Methods, Cartographic Design, Cartographic Effects, Symbology

When symbolizing a polygon layer using a color ramp, it is necessary for us to guarantee that adjacent polygons have very distinct colors. Adjacent polygons symbolized in two similar shades of the same color are not easily distinguishable. Is there an automated way to do this?

Mapping Center Answer:

The unique values symbology method automatically chooses the set of most different colors from the color scheme you select. However, if you've got more than 12 unique values and a narrowly defined color scheme you are fairly likely to have adjacent polygons with similar colors.  If you are actually showing categorical data then the only think you can do is make sure you choose a color scheme with a high range of Hue, Value, and Satuation.  Even then, I would likely fuss with the colors manually afterwards just to fine tune what someone will see on my map.  The trick I use there is to use the colors already in my color scheme by right clicking on them and saving the color so I can apply it to another value that I want to change (see the "refining colors as you work" section of the Working with Color help topic)

But, if your task is only to show that the polygons are different features, i.e., not showing any particular values or categories, then you can try using a four-color solution, which we documented on our Los Angeles Ethnicity map.

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