Dirty areas are created to flag areas where edits have been made to feature geometry and network attributes or where error features exist in the network. They serve as an indicator that a change to the network has occurred that is not reflected in the network topology. Dirty areas are cleared when the network topology is validated as long as no error features exist within the validation extent.
When the network topology is enabled, dirty areas are created to track edits. Edits can include creation of features, updating feature geometry, or modification of fields associated with network attributes. When the network topology is disabled, a single dirty area covering the entire extent of the network's spatial reference is displayed and any edits made will not generate additional dirty areas.
A dirty area is represented by a purple translucent polygon and tracks the extent of the edited feature, the type of edit, the global ID of the feature, and the editor who performed the edit. If a feature's geometry is modified, two dirty areas are generated for the single feature. One represents the envelope of the feature's previous geometry, and the other represents the feature's new geometry.
Operations that create dirty areas
Modifications to the following create dirty areas:
- Geometry
- Fields that are defined as network attributes
Error features that are created when you enable or validate the network topology will result in dirty areas.
View and manage dirty areas
You can access dirty areas as a sublayer of the trace network and symbolize them using core symbology tools. You can visualize dirty areas by turning them on and off like any other layer. For example, if you are editing your network and the dirty areas are visually distracting, you can turn off the layer. The dirty areas are still there, but you will not see them on the map. You can symbolize dirty areas based on attributes in the dirty areas layer. For example, editor tracking fields can display dirty areas in which a certain editor performed work or based on when the edit occurred. Use the UpdateType field to symbolize the dirty area by the operation type that created it.
Dive-in:
The type of dirty area is represented by the UpdateType field in the dirty areas attribute table. This field is assigned a system-provided coded value domain to classify how the dirty area was generated. Values for the coded value domain are insert, update, delete, and error as shown in the following table:
| Update type | Dirty area type |
|---|---|
0 | Insert |
1 | Update |
2 | Delete |
3 | Error |
Dirty areas associated with error features (UpdateType = 3) are not evaluated when the network topology is validated and will remain until the error situation is addressed through an edit to the feature in error.
Validating the network topology maintains consistency between what you see on the map and what is stored in the network topology. Analytic operations rely on the network topology and may return unexpected results if dirty areas exist. For example, if the path of a trace traverses a dirty area, the results may not be consistent with what you see on the map. The Validate Consistency option in the Trace tool ensures that trace results do not include results that intersect dirty areas.