Marker fill symbols add realism to your maps

By Aileen Buckley, Mapping Center Lead

Marker Fill Symbols - Thumb

Another way to create polygon symbols that appear more realistic is to use marker fill symbols that mimic what you would see on the ground, but also to vary them so that they do not clip at the polygon edges (figures 1 and 2).

Marker Fill Symbols - No Realism

Figure 1. A marsh symbol created as a marker fill symbol that clips at the edge of the polygon appears abrupt and unrealistic

Marker Fill Symbols - With Realism

Figure 2. Using cartographic representations, the symbol can be modified so that the marker symbols are not clipped, thus appearing more realistic

The approach we took to create the symbol for the swamp/marsh features on the Crater Lake area map used the following steps.

  1. In ArcMap, right-click the polygon layer and click Properties.
  2. On the Symbology tab, use the Features renderer (assuming this layer only contains marsh/swamp features).
  3. Double-click the symbol patch and click Edit Symbol.
  4. Change the Type to Marker Fill Symbol and click the Marker button.
  5. In the Symbol Selector dialog box, search for a marsh symbol. Scroll to the bottom to see the “Marsh, saltmarsh, or reeds” symbol in the Ordnance Survey style (figure 3).

    Marker Fill Symbols - Symbol Selector
    Figure 3. The marsh symbol in the Ordnance Survey style

  6. Select it and change the size to something that looks realistic for your map, for example, we used 4 points.
  7. Click OK.
  8. Change the color (we used HSV 95 27 68).
  9. Click the Outline button and change the color to No Color. Click OK.
  10. Select the Random option for the placement of the markers within the fill symbol (figure 4).
    Marker Fill Symbols - Symbol 1

    Figure 4. The Symbol Property Editor dialog box for the marsh marker fill symbol

  11. On the Fill Properties tab, experiment with the Separation X and Y values to find something that looks realistic on your map—generally, I find that I need to drop these values a bit (figure 5).
    Marker Fill Symbols - Symbol 2

    Figure 5. The Fill Properties tab of the Symbol Property Editor dialog box for the marsh marker fill symbol

  12. Click OK to keep all your changes.
  13. Make sure the polygon data you are symbolizing is in a geodatabase so that you can convert to representations.
  14. Right-click the layer in the table of contents and click Convert Symbology to Representations.
  15. Right-click the layer in the table of contents and click Properties.
  16. On the Symbology tab, click the Marker layer. You may have to reset the marker size. For Clipping options, choose either Whole markers cross boundary or No markers touch boundary (figure 6).
    Marker Fill Symbols - Reps

    Figure 6. The settings for the marker layer of the cartographic representations for the marsh symbol

  17. Click OK to keep all your changes.

Although the difference is subtle, a map reader with an experienced or inquisitive eye will notice your high-quality symbology.

Thanks to David Barnes, Cartographic Product Engineer, for his Crater Lake area map.

About the author

Dr. Aileen Buckley has been making maps since she was an undergraduate student. She has a Bachelors in Geography and Spanish from Valparaiso University, a Masters in Geography from Indiana University, and a Ph.D. in Geography from Oregon State University. She is a senior product engineer on the Living Atlas team, and her work focuses on determining and sharing best practices for mapping and analysis with modern GIS. She publishes and presents world-wide on many aspects of mapping and GIS. She is a co-author of Map Use: Reading, Analysis, Interpretation, and she is a co-editor for the Atlas of Oregon. Aileen is a former president of CaGIS (the U.S. cartographic association) and is actively involved with the International Cartographic Association in which she is the lead delegate for the United States.

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