Mapping and Visualization

How to scatter stacked or clustered marker symbols for point features

By Charlie Frye, Esri Chief Cartographer

Point Disperse Options

One of the most frequently recurring topics on Mapping Center is what to do with stacks or clusters of point features on maps. In August 2007, I wrote a blog posting on how to use Maplex to display coincident points, and this worked for some scenarios, but not all.

New with 9.3 is a tool called Disperse Markers; it’s in the Cartography toolbox, in the Symbolization Refinement toolset.  The only caveat to using this tool is that your data need to be stored in a geodatabase because the tool works on representation symbology. This will be easier for many map makers, and it will work for more scenarios than the Maplex solution did.

Here is the basic procedure:

  1. Symbolize your point features.
  2. Convert the symbology to representations.
  3. Run the Disperse Markers tool with your point representation layer as the input.

Here is an example of my results (using the same voter data I used in the Maplex example in which each voter is represented by a point whose color is based on political party affiliation):

Scatter Clustered Features - Figure 1 Scatter Clustered Features - Figure 2
Before: The points are stacked on top of each other, and there is no way know how many voters live at the same location. After: The points are dispersed and it is easy to see all the voters, even those in apartment buildings versus single family dwellings.

Some things to note:

About

I am Chief Cartographer at Esri, and manage the Cartographic Projects Group on the Content Team. I have been with Esri in Software Products since 1994. I am currently the author of Esri's Ecological Land Unit services, global ecological content, and the World Population Estimate Services. Contact me at cfrye@esri.com with questions or feedback.

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