In the previous lesson, you added and symbolized a layer that showed a large number of bombing missions during the Vietnam War. Currently, the only reference data on the map is the default Topographic basemap. This basemap is alright, but it contains more information than you need and has a color scheme that clashes with your purple missions. You'll add a layer of world countries that you can symbolize to better complement your missions. Then, you'll create a layer that shows countries that comprise your area of interest: Vietnam, Laos, and Cambodia, where the majority of missions occurred. You'll symbolize this new layer to draw attention to the focus area.
Add and symbolize a layer of countries
First, you'll add a layer that shows the countries of the world. You'll symbolize the countries with a gray color scheme to emphasize your purple bombing missions.
- If necessary, open your Vietnam War Bombing Missions project in ArcGIS Pro.
- On the ribbon, in the Map tab, in the Layer group, click the top half of the Add Data button (the icon).
The Add Data window opens. You can choose to add data from your project, your portal (if you're using an ArcGIS organizational account, your portal is likely ArcGIS Online), and your computer. The layers in Living Atlas are hosted on ArcGIS Online.
- For Portal, click Living Atlas.
The window displays some of the layers available in Living Atlas, but not all. You'll search for a layer of world countries.
- In the search bar, type World Countries and press Enter. Scroll through the list of results until you find World Countries (Generalized) by owner esri.
- Click the layer to select it and click OK.
The layer is added to the map.
The default orange symbology isn't particularly appealing. Additionally, the basemap is still visible.
- In the Contents pane, check the boxes next to World Topographic Map to turn off the basemap.
- Click the arrow next to World_Countries_(Generalized) to display the layer's symbol. Then, click the symbol to open the Symbology pane.
The World_Countries_(Generalized) layer may be part of a group layer that is also called World_Countries_(Generalized), causing the name to appear twice in the Contents pane. Living Atlas layers are sometimes added in groups, which organize your layers in the Contents pane and have no effect on how the layer is displayed on the map. If you want, you can remove a group by right-clicking it and choosing Ungroup. Alternatively, you can add a group by right-clicking the map name and choosing New Group Layer.
You'll symbolize countries with a plain gray symbol that has thick borders, emphasizing the division between countries. To better emphasize country borders, you'll add a glow effect.
- If necessary, in the Symbology pane, click Properties. If necessary, click the Layers tab.
The default symbol has two layers: one for the outline (also called stroke) and one for the fill.
- Click the fill layer to select it.
- Click the menu for Color and click Color Properties.
- In the Color Editor, for Color Model, choose Grayscale. Change Gray to 225 and change Transparency to 40%.
- Click OK.
The fill color for the countries is now a semi-transparent gray color. The outline is still orange. Rather than change the outline layer to a single, plain color, you'll add multiple outline layers that you'll then symbolize with a gray gradient of colors, imitating a glow effect around country borders.
- At the top of the Symbology pane, click the Structure tab.
This tab allows you to add, remove, and manage effects for aspects, or layers, of a symbol. You'll add two more outline (or stroke) layers in addition to the one that already exists.
- Under Layers, click Add symbol layer and choose Stroke layer. Repeat the process to add another stroke layer and confirm that you have three stroke layers total.
- Return to the Layers tab. If necessary, select the first (topmost) stroke layer on the list of layers. Open the Color Editor for the layer (click the Color menu and click Color Properties).
- In the Color Editor, change the Color Model to Grayscale. Change Gray to 45 and Transparency to 60%, then click OK.
- In the Symbology pane, change the Width to 0.05 pt.
This layer is the topmost stroke layer, so it'll be thinner and darker than the others.
- Following the same procedure, give the second (middle) stroke the following parameters:
- Color Model: Grayscale
- Gray: 96
- Transparency: 90%
- Width: 3 pt
- Give the third (bottom) stroke the following parameters:
- Color Model: Grayscale
- Gray: 96
- Transparency: 95%
- Width: 7 pt
- Once all three stroke layers have been symbolized, click Apply.
The plain gray fill emphasizes the bombings, while the three-stroke outline makes national boundaries stand out.
Create a layer for the area of interest
Next, you'll further emphasize the three countries of particular interest to your map: Vietnam, Laos, and Cambodia. As your map already indicates, these three countries received the vast majority of bombings. To elevate these countries in the visual hierarchy of your map without overwhelming the bombing missions data, you'll change the outline of your focus area to a purple glow that complements the existing symbology. To change the symbols for only your focus area, you'll duplicate the countries layer and filter it to show only Vietnam, Laos, and Cambodia.
- In the Contents pane, right-click the World_Countries_(Generalized) layer and choose Copy. Then, right-click the Bombing Missions map item and choose Paste.
A copy of the layer is added to the pane, on top of the Bombing_Missions layer. You'll move the copy so that it doesn't obscure the missions.
- Drag the copy below the Bombing_Missions layer, but above the original World_Countries_(Generalized) layer.
Next, you'll change the copy's name and filter it to show only Vietnam, Laos, and Cambodia.
- Double-click the copy to open its Layer Properties window. In the General tab, change the name to Focus Countries.
- Click the Definition Query tab.
A definition query is an expression that you create using values and fields within a layer's data to filter or select specific attributes of that layer. For instance, if you wanted to display only Vietnam in the Focus Countries layer, you'd create a query clause that said Country is Equal to Vietnam. You want to display three countries―Vietnam, Laos, and Cambodia―so you'll create three query clauses, one for each country.
- Click New definition query.
- Use the menus to create the query clause Country is Equal to Vietnam. Press Enter to input the clause.
- Click Add Clause and add the query clause Or Country is Equal to Laos. Press Enter.
For query clauses beyond the first, you're given the option to begin the clause with And or Or. And means that the features selected by the query must conform to both clauses, while Or means that the features conform to only one or the other. No country can be both Vietnam and Laos at once, so Or is the appropriate choice.
- Add a third clause: Or Country is Equal to Cambodia. Press Enter.
- In the Layer Properties pane, click OK.
The definition query is applied to the layer. All features that fail to meet the criteria you specified are hidden. It's currently difficult to tell whether your query was successful, because the original layer of countries is still active.
- In the Contents pane, check the box next to the World_Countries_(Generalized) layer to turn it off.
While the layer contains only the countries that are most relevant to the map, they're still depicted as three separate features. When highlighting your map's area of interest with a glow effect, it'll be better to have the effect only border the area as a whole, not the national boundaries within it. You'll merge the three features into one with the Dissolve geoprocessing tool.
- Open the Geoprocessing pane (on the Analysis tab, click Tools).
In the search box, type Dissolve. Click the Dissolve tool.
- For Input Features, choose Focus Countries. For Output Feature Class, confirm that the output location is the project's geodatabase (Vietnam War Bombing Missions.gdb) and change the output name to Focus_Countries_Merged.
The remaining fields allow you to dissolve only certain features based on specific fields or statistics. You want to dissolve all features in the layer, so you'll leave these parameters unchanged.
- Click Run.
The tool runs and the layer is added to the map. The new layer contains Vietnam, Laos, and Cambodia, but the boundaries between the countries are dissolved so that only a single feature remains.
- Turn off the original Focus Countries layer.
Highlight the area of interest
Next, you'll symbolize the dissolved feature layer to give it a purple gradient that will emphasize the area without clashing with or overwhelming the bombing missions. Although the gradient will mostly appear around the border, you'll use existing gradient effects for the symbol's fill to represent it.
- Open the Symbology pane for the Focus_Countries_Merged layer. If necessary, click Properties and go to the Layers tab.
The symbol has the three stroke layers you created earlier, which you'll turn off so they don't overlap with the stroke layers for the World Countries (Generalized) layer. Then, you'll adjust the settings for the fill layer to create a purple gradient near the border.
- Uncheck the boxes next to the three stroke layers to turn them off. Click the fill layer to select it, then click the layer's menu and choose Gradient fill.
First, you'll change the leftmost color on the gradient, which represents the color closest to the border of the feature. This color will be the darkest color in the gradient in order to emphasize the border around the area of interest.
- In the Appearance section, for Colors, click the left color menu (not the gradient menu) and choose Color Properties.
You'll use the same deep purple color you used for the missions. Unlike the missions, the gradient fill won't overlap with many other features, so increasing its transparency will cause it to appear much lighter than the missions (and prevent the gradient from concealing them).
- In the Color Editor, change the Color Model to RGB. Change the HEX # to 4C0073 and the Transparency to 90%.
- Click OK.
Next, you'll change the rightmost gradient color. You'll use the same color, but increase the transparency to 100 percent, causing the gradient to fade away completely as it extends from the border.
- In the Symbology pane, for Colors, click the right color menu and choose Color Properties.
- In the Color Editor, change the HEX # to 4C0073 and the Transparency to 100%. Click OK.
- In the Symbology pane, click Apply.
The color looks good, but the gradient's pattern has problems. Because you're using the fill layer to the set the gradient, the default pattern causes the gradient to spread across the entirety of the feature. Additionally, the default interval (the rate at which the color changes from the first gradient color to the last) is low, causing the gradient to look unnatural. You'll reduce the size of the pattern and increase the gradient interval for a more natural effect that only appears around the feature's border.
- In the Symbology pane, click Pattern to expand it.
- Change the Interval to 12. Change the Size to 12%.
- Click Apply.
- In the Contents pane, turn on the World_Countries_(Generalized) layer.
When the world countries are turned back on, the light purple gradient becomes darker because of the gray countries symbol under it. You'll adjust the layer transparency of the focus countries to make the gradient appear lighter.
- In the Contents pane, click the Focus_Countries_Merged layer to select it. On the ribbon, click the Appearance tab. In the Effects group, adjust the Layer Transparency to 60.0%.
The area of interest is now more subtly highlighted on the map.
- Save the project.
In this lesson, you contextualized your bombing missions with data about the countries in the area where the mission occurred. You symbolized the countries with an unobtrusive gray color and highlighted the focus area with a purple gradient. In the next lesson, you'll add reference data about cities and terrain, then symbolize and label the data appropriately.