Mapping

Polygon fill symbols add realism to your maps

By Aileen Buckley, Mapping Center Lead

Polygon Fill Symbols - Thumb

When working with polygon data, it is common to symbolize these features with a colored fill and an outline (figure 1). However, if you are trying to create a realistic impression on your map, this symbology works against you. In the real world, we rarely see lines around areas, and the inside of those areas is rarely the same color everywhere.

Polygon Fill Symbols - No Realism

Figure 1. Commonly used polygon fills with outlines, solid fills, and regularly placed interior patterns do not add a realistic appearance to a map.

To add realism to polygon features, here are three tricks you can use (figure 2):

Polygon Fill Symbols - With Realism

Figure 2. To add a realistic appearance to a map, remove outlines, vary fill colors, use random patterns within fills, and do not clip marker fill symbols at polygon edges.

You saw an example of adding variation to a polygon symbol using gradient fills in our sun glints example. That is a great solution, but in our next two blog entries, you will see how to use picture and marker fill symbols to add variation as well. You will also see how you can use cartographic representations to create fill symbols that do not clip at the edges of the polygons.

This example is a map of southwestern Oregon in the Crater Lake area (figure 3). On this map, there are a variety of features to experiment with, including dry lakes, intermittent lakes and swamps/marshes.

Polygon Fill Symbols - No Realism

Figure 3. The Crater Lake area map

In the next blog entry, you will see how to symbolize the lakes using picture fill symbols. In the blog entry after that, you will see how to use marker fill symbols to symbolize the marshes.

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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