Our concern in this section of the lesson is to create symbols for discrete features like schools or police stations. Often there are variations (i.e. attributes) within the features that you may want to highlight. These differences could be nominal (i.e. qualitative), like different types of schools (e.g. public, charter, private), or ordinal (or quantitative) like different levels of schools (e.g. primary, intermediate, secondary). Qualitative differences are best symbolized with different hues or different shapes. Quantitative differences are best symbolized with color values, saturations or sizes. Refer to thesymbolization concept for more info on this. In this part of the lesson you again can make your own design choices. You can follow these steps as guidelines, or as practice, or just read through them.
Learn more about custom symbols in the Concept Gallery.
A. Custom Point Symbols
Following is an example of how you can customize point symbols.
- Symbolize schools by LEVEL (in the Symbology tab of the Layer Properties ). Remove the N/A and unnamed fields from the list (they will now appear as all other values). Uncheck the box next to <all other values>. And click OK to apply changes.
- In the Table of Contents, click on the symbol for Primary/Elementary schools. The Symbol Selector window opens. ArcMap includes a wide variety of symbols but not all of them are immediately visible.
- Click the Style References... button and choose Civic from the list of symbol sets. Notice the default visible sets are Esri and one named for your computer user profile.
- Scroll down through the list of symbols - it is now substantially longer - and click on School Building 1 (not School 1).
- You can change the color, size, and angle of the symbol in this window but let's look deeper. Click the Edit Symbol... button. This opens the Symbol Property Editor.
- Notice the Layers area in this window. Your schoolhouse symbol is actually constructed of two layers: a white fill color and a black outline. Both are individually editable.
- Click on the lower (white fill) layer and then change the Color drop-down menu to a color that will be visible on your borough color.Look back at the Layers area. There are some additional controls here that are worth a note. Each layer has a checkbox to the left that controls visibility. Below the layers are buttons that add a new layer, delete the selected layer, change the order (up and down) of the selected layer, copy, paste, import and edit tags on a layer.
- Click the Mask tab. Under Style, click Halo. You can change the size of the halo in this window. To change the color of the halo click the Symbol... button. It will open a new Symbol Selector window for the halo.
- For thefill color, in the options box, select the color you are using for your Bellefonte borough polygon. This way the halo will not be noticeable but will break the lines that the school symbol is touching. Click OK to accept the changes.
- Create new symbols for the Intermediate/Middle andSecondary/High schools. Because there is an inherent ordinal nature to schools (grades k through 12), you could reasonably use different values of the same hue for the other two school symbols. It is standard to associate darker values with higher or more. Or you may decide to symbolize the schools all alike.
- Explore these windows and settings to create symbols for the other data layers as you see appropriate.
B. Custom Line Symbols
All of the editor windows you visited in the last part are also available for line and polygon features. The process is one of drilling down into successive properties windows to find the settings of interest. The thing to remember is that every symbol - points, lines, polygons, and text - is constructed of editable properties. Here is an example for linear symbols.
- Symbolize the railway layer using Status as the Value field. Click Add All Values. "Active" and "Inactive" should appear as the two values. Deselect the check mark next to All other values.
- Double-click the symbol for Active railways to open the Symbol Selector.
- In the list of symbols, select railroad.
- Click the Edit Symbol... button to open the Symbol Property Editor . Like above, look at the Layers area. There should be two layers. The top layer is listed as a Hash Line Symbol in the Type drop-down menu. And the second layer is a Cartographic Line Symbol.Click through the tabs for these two layers to see some of the customizations possible. Experiment with settings, at least in the Template tab. Also look through the other lines possible under the Type drop-down menu.
- Click OK if you created an active railway symbol you would like to use. Or Click Cancel to get out of the editor and use the standard railroad symbol.
- Go into the Symbol Selector for the inactive railway symbol and edit or create a linear symbol that is different from the active railway symbol.
- Click OK to dismiss the windows.
C. Custom Polygon Symbols
There are many instances when you may want to arrange multiple polygon features on top of one another. How do you keep all of the features clear? Transparency is one option (Layer Properties > Display tab > Transparency), but color changes created by transparent layers are not easily understood by readers or correctly reflected in the legend. Another approach is to create a polygon symbol that is not a solid color. In this example from the Penn State parking map, some parking lots have solid color fills and other have see-through hatch symbols.
- Add the flood_plain shapefile to the map if you have not already.
- Open the Symbol Selector window for the flood_plain fill symbol. Click the Edit Symbol... button.
- Change the Type: drop-down menu to Line Fill Symbol.
- Add another Layer to the symbol ("+" button in lower left). The new layer should be a duplicate of the original.
- Select the upper symbol layer (if it is not already highlighted). Specify: Color: a medium blue; Angle: -45; and Separation: 7.0.
- Select the lower symbol layer. Specify: a white line, -45 angle, offset of 1, and Separation of 7. The pairing of dark and light lines in the new symbol will allow it to be visible over both light and dark colors.
There are times where you may want to truly create a symbol from scratch. You can create a symbol from a picture graphic by importing a picture file (as a BMP or EMF) via the Style Manager. This will be demonstrated in Lesson 3 for a road label.
D. Apply These Topics to Your Map
- Open your reference map document. Save your practice map if you want.
- Look over the features. Are there any that would benefit from the skills you have just learned? Take some time and experiment with the symbol editors, but remember the purpose of the map. Don't create symbols simply because you can, make sure that your choices add to the effectiveness of the map.
E. Save the Map Document
You have just completed Part III, which dealt with creating custom symbols. In Part IV, you will create a page layout.