Week 6: Following Rivers Through Time

Intro to Symbolization in AEJEE

Symbolization is the process of choosing how to represent the features on a map. The symbols we choose should help describe additional information about the features on the map. Poor symbolization leads to inaccurate, misunderstood, or even deceptive information, while effective symbolization helps to communicate information quickly and clearly.

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Download Geographic Data About Louisiana

• Right-click (Win) or control-click (Mac) the link below to download the zipped file to your computer.
• Unzip the file. A folder called LouisanaAE will be created.
• Move the entire LouisanaAE folder into the AEJEE Data folder. (Path: ESRI/AEJEE/Data/LouisianaAE)

Launch AEJEE, Open the Louisiana Project File, and Add a New Layer

• Launch AEJEE by double-clicking its icon on your desktop or by clicking its icon in the Dock (Mac) or Launch Bar (Win).
• Choose File > Open, navigate to ESRI/AEJEE/Data/LouisanaAE, select the LA_Rivers.axl file, and click Open.
  
• A map of Louisiana is displayed when the project opens. Parishes are shown in tan and the Mississippi River is blue.
• Click the Add Data button, navigate to the LouisianaAE folder, select cities.shp, and click OK. This layer maps cities in Louisiana and should now be the top layer on your map. Note: The cites layer is automatically turned on when it is added.

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Explore the Attribute Table of the Cities Layer

Each layer of a GIS project includes a database of information about its features. This information is presented in an Attribute Table, which is linked to the map features associated with that layer.

• Click the cities layer in the Table of Contents to make it the active layer. Right-click (Win) or control-click (Mac) the cities label in the Table of Contents and choose Attribute Table from the menu. Scroll through the fields (columns) and the data records (rows) in the Attribute Table.
  • To open the Attribute Table, right-click (Win) or control-click (Mac) the layer name in the Table of Contents and choose Attribute Table from the menu.
    
  • The Attributes of cities window opens. Drag the horizontal scroll bar to examine the different fields (columns) in the Attributes of cities table and drag the vertical scroll bar to see information for the different cities (records).
     
    Scroll across the Attribute Table.
     
• What type of data is given about cities?
  • FID (Feature ID.)
  • AREANAME (Official name of the area.)
  • CLASS (The type of area: city, town, village, borough, or CDP - Census Designated Place.)
  • PLACE (A numeric code for the individual places in the CLASS field.)
  • FIPS (5-digit place code assigned under the Federal Information Processing Standards.)
  • POP_90 (Population according to the 1990 Census.)
  • POP_98 (Population estimated for 1998 by the US Census Bureau.)
  • HOUSEUNITS (Number of housing units in the place in 1990.)
  • AREALAND (Area of land in the place, in square miles.)
  • AREAWATER (Area of water in the place, in square miles.)
• How do you find out what the field names mean?
• Close the Attributes of cities window.

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Adjust the Color, Size, and Type of Symbol Used to Represent Features on the Map

The Properties window in AEJEE.

When you added the cities layer, you may have noticed that it was automatically assigned a color. This initial color choice for the data is random. Compare the color of the city dots to the colors in the other layers. You may find that there is not enough contrast between colors or that the cities came in with the same color as another layer, making them difficult to see. It may be necessary to change the color of the city dots. The symbols used to represent features in a layer can be modified in that layer's Properties window.

• To open the Properties window for the cities layer, right-click (Win) or control-click (Mac) the cities label in the Table of Contents. Choose Properties from the menu. Then move the Properties window so you can see both it and the map at the same time.
  
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  • To open the Properties window for the cities layer, right-click (Win) or control-click (Mac) the cities label in the Table of Contents. Choose Properties from the menu.
    
  • Drag the Properties window to a location where you can see both it and the map at the same time.
    

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Symbolize by Color

In the Properties window, change the color of the cities to Brown. Select the following options:

• Draw features using: One Symbol
• Style Circle
• Color Brown
• Size 6
• Click Apply and Click OK

Show me how to change the color of the cities

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In the Properties window, choose a color that contrasts well with the map. Explore the built in color options as well as the custom ones in the Color drop down menu.

Show me some of the custom color options

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After choosing Custom from the drop down color menu these color Swatches are displayed in the Color Chooser. 

You can also select the HSB custom color option to adjust Hue, Saturation, and Brightness. 

In addition, you may want to select the RGB custom color option to adjust Red, Green, and Blue color options. 

Show me an example

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In this map, Louisiana cities are represented by bright green custom colored dots. 

Symbolize by Symbol Type

Instead of using dots to represent cities, you may want to choose a different type of symbol. In the Properties window, change the symbol style of the cities to Triangle. Select the following options:

• Draw features using: One Symbol
• Style Triangle
• Color Brown
• Size 6
• Click Apply and Click OK

Show me how to change the symbol style of the cities

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In the Properties window, click and hold on the Style pull down menu. Change the Style from Circle to Triangle. 
 
In this map, Louisiana cities are represented by Brown Triangles.

In the Properties window, choose a symbol that you think makes sense for representing cities. Experiment with other choices in the Style drop down menu.

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In this map, Louisiana cities are represented by Brown Squares.

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Symbolize by Size

If you chose triangles as your new symbol for cities, you may notice that they appear smaller than dots. In this case, you may wish to increase the size of the symbols. In the Properties window, change the size of the symbol of the cities to 10. Select the following options:

• Draw features using: One Symbol
• Style Triangle
• Color Brown
• Size 10
• Click Apply and Click OK

Show me how to change the size of the symbol of the cities

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In the Properties window, change the size by clicking on the up or down arrows of the Size menu.

In this map, the size of the symbols representing cities has been changed to 10. 

In the Properties window, choose a size that you think makes sense for the symbol you are using to represent cities. Experiment with other choices in the Size drop down menu.

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In this map, Louisiana cities are represented by Green Squares that are 8 points in size.

Show me a movie about changing the color, size, and type of symbol in AEJEE

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Add Meaning to the Symbols to Differentiate Between the Features on the Map

At this point, every city in Louisiana is represented by the same symbol and with the same color. The residents of these communities will be quick to tell you that Louisiana's cities are not all the same! Using appropriate symbolization, you can communicate information about the cities beyond their locations.

In the Properties window, change the symbolization for the cities using the following options:

• Draw features using: Unique Symbols
• Field for values AREANAME
• Color Scheme Random
• Style Circle
• Size 8
• Click Apply and Click OK

1. Right-click on the PC or control-click on the Mac the cities label in the Table of Contents. Then select Properties. Click on the Draw Features using: drop down menu and choose Unique Symbols.
   
2. Choose AREANAME for Field for values and Random for Color Scheme. The Style default is Circle and Size default is 8 points.
   
   
3. This polkadot map of cities in Louisiana is the result.