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Cartographic Lines

July 29 2009 | 0 comments
Categories: Cartographic Representations

I am placing decorations on dashed lines and the decorations are polylines stored in a feature class. Is there a way to lock the dashes distribution so I can align the decorations on the solid parts of the line. I lay them out correctly but the line dashes move when I export or print again. I know I should use representations but I need a easy way to get our line decorations into representation form. Is there an easy way to do this rather than converting to PDF then open in Illustrator and then saving as a TrueType font and importing then into the representation?

Mapping Center Answer:

There are two main types of geologic line symbol decorations. The first type is a line decoration that repeats at regular intervals along the line. An example of this would be the triangle used to represent a thrust fault.  The second type of line decoration is one that is palced manually along the line. An example of this are the double arrows used to represent an anticline.  In either case, the only way you can control the placement of the decorations relative to the line dash is by using representation symbology.

One way to simplify the process is to download the Geologic Mapping Template from the ArcGIS Map Templates Resource Center. The Geologic Mapping Template contains a file geodatabase schema with predefined representation geologic symbology, documentation and tools. All of the symbols have been designed following the specifications outlined in the FGDC Digital Cartographic Standard for Geologic Map Symbolization and under the guidance of the USGS.  By design, all line symbol decorations fall on the solid part of the line dash.

To use these symbols, you can either append your data to the corresponding feature classes in the template database or you can apply the representation symbology to the feature classes in your database. The Getting Started with the Geologic Mapping Template explains how to append your data to the template database.

If you choose to apply the predefined symbology from the template database to your feature classes, follow the steps outlined below.  Thrust faults are used in the example, but the process is the same for all symbols. 

To apply representation symbology from the template geodatabase to your database:

1. Save representation rules from template database to personal style

a. Load the "Faults" feature class from the “GeologicMap” feature dataset (ESRI_Geology.gdb) into a new ArcMap document

b. Right-click layer and select properties Select Representations on the Layer Properties Symbology tab Select “thrust fault (1st option) – Identity and existence certain, location approximate” (Symbol name and FGDC Reference Number 2.8.3) and click the lower right arrow and choose "Save Rule"
c. Repeat this for all the symbols needed and clear the map document (prevents locks)
2. Create a representation class for your feature class

a. Add your existing feature class to a blank ArcMap document

b. Symbolize features using the Single symbol option
c. Right-click layer and select Convert Symbology to Representation
3. Apply saved representations to your new representation class

a. In the layer properties menu under representations, click the black arrow again and select “load rule”

b. Scroll to the bottom of the symbol window and you’ll see the selected symbology you exported from the Geologic Mapping Template
c. Select symbol and rename symbol
d. Repeat this for all symbols you want to use

Calculate the RULEID field in your feature class attribute table to reflect the Rule ID integer value that corresponds to representation symbology you want to use for each feature type.

You can review the properties for representation symbology to determine whether or not a line decoration for a given symbol is placed at repeating intervals or placed manually. With the exception of folds, normal faults and strike-slip and oblique-slip fault symbols, all lines with decorations are composed of a repeating pattern for the line symbol decoration.

Folds, normal faults and strike-slip and oblique-slip fault line symbol decorations are placed on a line using a control point. You can add control points to a line manually in an edit session and/or by using the Set Representation Control Point at Intersect tool in the Cartography Tools toolbox. The Geologic Mapping Template details how to add control points to a line.

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