The parcel fabric offers a variety of flexible data quality management capabilities in ArcGIS Pro. These capabilities include the following:
- Geodatabase topology
- Attribute rules
- Least-squares adjustment
- Configured data quality layers
- Gap and overlap detection
These capabilities are configurable and can be used in quality-driven workflows to evaluate and fix common data quality issues in parcel data. Each capability has advantages and disadvantages described below.
A parcel fabric is created with a geodatabase topology containing a required set of topology rules. These topology rules define and enforce the topological relationships between parcel features.
You can configure additional topology rules for topological relationships between parcel feature classes and for topological relationships between parcel feature classes and other feature classes. For example, you can add a rule that requires a parcel type to be completely contained by another parcel type.
Topology rules are validated in the Error Inspector pane to identify rule violations. Rule errors are displayed as error features and can be fixed in the map.
One advantage of a geodatabase topology is its ability to model different behaviors for parcel types using different sets of rules. Rule violations can be viewed and fixed in the map using error features and predefined topological fixes.
A disadvantage of a geodatabase topology is its inability to distinguish between historic and nonhistoric parcel features. Validating a topology modifies the data by performing cracking and clustering.
The parcel fabric is created with a set of default attribute rules. Attribute rules are geodatabase rules that can be used to automatically populate attributes, constrain invalid edits during edit operations, and evaluate data.
Optional preconfigured parcel fabric attribute rules are also available for import. You can configure your own attribute rules in addition to the default and optional parcel fabric rules.
Attribute rules are configured using Arcade, which is a flexible scripting language that allows you to build custom expressions that reference both feature attributes and geometries. For example, you can configure attribute rules to perform batch field calculations, prevent incorrect edits from being saved, and evaluate data.
A least-squares adjustment can be run on a selection of parcels to evaluate and improve spatial accuracy. For the most reliable results, a least-squares adjustment should only be run on parcels with lines that have record-accurate COGO dimensions.
A least-squares adjustment can be used in two ways to evaluate and improve spatial accuracy:
- Perform a consistency check on a parcel network of COGO dimensions to detect possible mistakes or outliers. Point locations are not updated.
- Use control points in a weighted adjustment to estimated more accurate coordinates for points. Point locations are updated.
A least-squares adjustment requires good estimation of a-priori accuracies and may require several runs before the chi-test passes. The adjustment will not return meaningful results when run on parcel lines that have inversed dimensions (dimensions generated from shape geometry).
Currently the parcel fabric least-squares adjustment cannot be used for coordinate-based cadastres.
Configured data quality layers
Configured data quality layers are available for parcel fabric feature classes. Configured data quality layers are map visualisation layers that have been specifically configured to show potential data quality issues in the parcel fabric. Examples of issues are lines that are too short and lines with too many vertices. Configured data quality layers can be used to quickly identify erroneous features in parcel fabric feature layers.
The following configured data quality layers are available:
- Distance mismatch—Displays parcel lines with COGO distances that do not match their shape lengths.
- Too short—Displays parcel lines with shape lengths that are shorter than the configured tolerance.
- Line vertices—Displays parcel lines with vertices.
- Vertices—Displays parcel polygons with vertices.
Gaps and overlaps
Use the Highlight command in the Gaps and Overlaps group on the Quality tab to find gaps and overlaps between parcels. Gaps and overlaps are highlighted in the current map extent.