In geographic information systems, defining boundaries around features is a fundamental task for visual emphasis, spatial analysis, and map layout customization. ArcGIS Pro offers multiple workflows to create outlines around selected features or to set map frame extents relative to index features. These techniques allow users to visually segregate areas of interest, apply symbolic emphasis, and control the spatial presentation of data. This article outlines the primary methods for generating feature outlines and managing map extents in ArcGIS Pro, based on documented procedures from Esri support resources.
Creating Outlines Around Selected Polygon Features
An outline can be used to define boundaries or highlight areas of interest within a polygon feature layer. In ArcGIS Pro, outlines are typically created by modifying the symbology of features or by generating new geometry that represents the boundary.
Symbology-Based Outlines
One approach to creating an outline involves adjusting the symbol properties for selected features within a polygon layer. This method does not alter the underlying geometry but changes the visual representation to emphasize boundaries.
- Select the polygon features to be outlined using standard selection tools.
- Access the Symbology pane for the feature layer.
- Set the primary symbology to Unique Values and add all attribute values.
- Customize the outline appearance (e.g., outline width and color) for the selected features within the Format Polygon Symbol pane.
- Apply the changes to render a visual outline around the selected polygons.
This technique is useful for quickly highlighting features without creating new geometry.
Geometry-Based Outlines Using the Buffer Tool
For a more permanent outline, the Buffer tool can generate new polygon features that represent the boundary of selected features. This method edits the existing feature class by adding outline features.
- In the ArcGIS Pro project, open the feature layer containing the polygons to be outlined.
- Select the desired features in the map view.
- Navigate to the Edit tab and click Modify, then search for and select the Buffer tool.
- In the Buffer pane, ensure the Dissolve option is checked under the Values section.
- Click Buffer to generate the outline features.
The resulting outline appears as a visual boundary around the selected features, which can be symbolized independently.
Selecting Features by Location
The Select By Location tool enables users to select features based on their spatial relationship to features in another layer. This tool is essential for identifying features that intersect, contain, or are contained by other features, which is often a prerequisite for creating outlines or setting extents.
Using Select By Location
To apply the Select By Location tool: - Click Selection > Select By Location to open the dialog box. - Choose the target layer(s) containing the features to be selected. - Specify the source layer(s) containing the features used to define the spatial relationship. - Select a spatial relationship operator (e.g., "intersect," "contain," "touch"). - Execute the selection to highlight features that meet the spatial criteria.
Spatial Relationship Operators
Several operators define how features relate spatially: - Intersect: Selects features that share any part of their geometry with the source features. - Contain: Selects features that completely contain the source features without sharing boundaries. - Touch: Selects features whose boundaries touch the source features, based on the Clementini definition. - Identical to: Selects features whose geometries are strictly equal to the source features. - Crossed by the outline of: Selects features whose boundaries share at least one edge, vertex, or endpoint with the source features but do not share a line segment.
These operators allow precise control over which features are selected based on their spatial relationships, which is critical for subsequent outlining or analysis.
Setting Map Extents with Map Series Constraints
In layouts containing a spatial map series, the extent of a map frame can be linked to index features to ensure consistent and accurate spatial representation across multiple pages or map series elements.
Linking Map Frame Extents
Map frame extents can be controlled using several options: - Linked map series center: Sets the map frame to the center of the index feature. A layer can be selected as an intersecting layer to include the boundaries of all features within the linked map frame extent. A margin can be added to set a fixed buffer between the extent and the map frame edge. - Linked map frame center and scale: Matches the center and scale of the linked map frame. Zooming and panning are disabled when the map frame is activated. - Linked map frame scale: Matches the scale of the linked map frame. Panning and rotation are allowed, but zooming is not.
Map Series Constraints
When a layout contains a spatial map series, map series constraints are automatically applied to the map frame containing the index layer. These constraints ensure that the map frame extent remains consistent with the map series requirements, such as centering on index features or maintaining a fixed scale.
Conclusion
Creating outlines around features and setting map extents are essential tasks in ArcGIS Pro for enhancing visual clarity and ensuring accurate spatial representation. By using symbology adjustments or the Buffer tool, users can generate clear boundaries around selected polygons. The Select By Location tool allows for precise feature selection based on spatial relationships, which is foundational for many GIS workflows. Additionally, linking map frame extents to index features through map series constraints ensures consistent and professional map layouts. These techniques provide users with the flexibility to emphasize areas of interest and control spatial presentation effectively.