Monday, March 04, 2013

Visualising overlapping boundaries of polygons side by side in ArcMap

I am writing post to show how to display symbology differentiating the overlapping polygon borders. This process involves symbology changes for layer being displayed.


Initially when a polygon layer is added and symbolized as unique values the map looks similar to this.
Polygon with unique value symbols

Then the individual polygon symbology is changed using "symbol selector".  In the symbol selector "Edit Symbol" is used to define the new symbol.
Symbol selector

The "symbol property editor" with the default fill symbol is as shown below:
Symbol property editor - default with simple fill symbol

In this "Symbol Property Editor" the following changes are made for each symbology 
  1. Type - Gradient Fill Symbol
  2. Intervals - 2 (splits into 2 colors, one for fill other for different color at border)
  3. Percentage - 3 (can be set to a lower value, based on the visual appearance)
  4. Style - Buffered
  5. Color Ramp - Select a required color ramp.

Symbol Property Editor - With final values for Gradient fill with Buffered style.

After individually changing the symbology of each polygon symbol, the final output is shown below.


One of the  issue found here is that the percentage seems to be is based on area of the polygon, making the Kerala polygon symbology to be smaller width.

This would help in better visualization of the polygons which overlap and both the borders need to be depicted with different colors.