Ask A Cartographer

Overlapping polygon outlines with representations

September 12 2007 | 0 comments
Categories: ArcGIS Methods, Cartographic Effects, Cartographic Representations, Symbology

Sometimes when displaying data, for adjacent polylines, the same line for the adjacent
polylines have the same symbol, the pattern may overlap, but not consistently. For instance a
solid line with an open circle (marker) that overlaps another line with the same symbol, how do you make the markers overlap each other, like the lines overlap each other. The markers intersect but do not overlap 100%. Is this easy to do?

Mapping Center Answer:

There are two aspects to this problem that will need to be addressed.

First, there is no way to assign a line symbol to your polygon’s outline that will work as you require. The reason is that when two polygons share an edge there’s no way to predict where that edge starts and ends relative to the start/end node of each of the polygons. Thus, the outlines will need to be converted to and symbolized as line features. The Polygon to line tool will create the line features you need to do this. Specifically, the results of polygon to line collapse the topology of the polygons (this effectively replicates what the old ArcInfo command BUILD LINE did).

Second, to properly symbolize the result of the Polygon to line tool, you’ll need to store that line feature class in a geodatabase, because you will need to use some of the new (at 9.2) cartographic representations symbology to get the markers to align. To do that, follow these steps:

(These steps turned into a Mapping Center blog entry called Creating dash-dot symbols for polygon outlines)

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

Contact Us | Legal | Privacy |