Ask A Cartographer

Contrast style for district data representation - reg.

August 10 2010 | 0 comments
Categories: Cartographic Design, Symbology

I want to depict the district with contrasting colors as the adminstrative boundary does not have any measured value.
1. Do we have specialized style and you would like to share?
2. There are two situations a) more and small polygons b) less and big polygons. My question is can I have two styles together for depicting single layer.

Mapping Center Answer:

Regarding your first question, a quick and easy way to assign different colors is to use the Unique Values type of renderer (on the Symbology tab of the Layer Properties dialog) and then use a value field like the Object ID (so that each polygon has a unique value, and then select one of the default color schemes (as in the attached image) that are in the Esri default style. The only problem with this is that since the colors are randomly assigned, you may have two polygons next to each other with the same or nearly the same color. Simply edit one of the colors and you should be good to go.

An alternative is a method that we wrote up in the bottom notes of our Making Beautiful Maps...with GIS session from this year's user conference -- this was done pretty easily by adding a new field to the polygon feature class, selecting the polys that would contain a certain color, and then calculating the field value to be that color name. Then this was repeated for the polys that would have the second color, and so one.

A third solution is a script that you can download that does this for your automatically. The Four Color Map tool is the solution. It will add a field to your data and assign one of four values to the field, then all you have to do is assign a unique color to each of the four values.

Regarding your second question, you can assign two different symbologies to the same feature class but you need to have two copies of the feature class in your table of contents in ArcMap. For one, on the Definition Query tab of the Layer Properties, use a query that defines which features you want to show with one of the symbology methods, then set the symbology. This will only be applied to the features that you define in the Def Query – the others will not show up in ArcMap. Then, for the other copy of the feature class in the table of contents, use the Def Query to show the other features and set the symbology for them. The two copies of the feature class will then show all of the features collectively, but the symbology is set for the select set of features defined by the Def Queries.

If you would like to post a comment, please login.

Contact Us | Legal | Privacy |