About associated feature classes and the parcel fabric
This topic applies to ArcEditor and ArcInfo only.
It is common for feature classes to be related to parcel boundaries. For example, road centerline and sewer feature classes must maintain a spatial distance from the boundary of a land parcel, zoning districts must follow the boundaries of land parcels, and building footprints must lie inside the boundaries of land parcels. It is thus typical for feature classes to be edited using parcel boundaries as a background reference. For example, road centerlines are constructed at a specified distance from the road frontage boundary of a parcel.
The parcel fabric acts as a background reference for related feature classes. When the parcel fabric is adjusted through a least-squares adjustment, parcel corner point coordinates may change and update with new values, resulting in discrepancies between the fabric parcels and overlying feature classes. It is important for feature classes based on the parcel fabric to be adjusted similarly, thereby maintaining their relative position.
The feature adjustment tool
For standard feature class layers to maintain alignment with the parcel fabric, they must receive the same adjustments as the parcel fabric. Feature classes that are associated with the parcel fabric can be adjusted to maintain alignment with the parcel fabric using the parcel fabric feature adjustment tool. The feature adjustment is based on the rubbersheeting process used in the ArcGIS spatial adjustment.
When parcel fabric points are adjusted, new coordinates for the adjusted points are compared against the original coordinates. A set of displacement vectors between the new and original coordinates are generated and stored in the Fabric_Vectors table in the geodatabase. The parcel fabric stores a sequential record of all the displacement vectors occurring from all least-squares adjustments. The feature adjustment tool uses these displacement vectors in a rubbersheeting transformation to adjust associated feature classes back into alignment with the adjusted parcel fabric.
It is important to distinguish between a feature adjustment and the fabric least-squares adjustment. The least-squares adjustment adjusts parcel fabric coordinates, which generate displacement vectors (between the old and new coordinates). The feature adjustment uses the displacement vectors to spatially adjust associated feature classes.
A feature adjustment can only be done if a least-squares adjustment has been performed on the parcel fabric.
For standard feature classes to be eligible for feature adjustments, they must be associated with the parcel fabric.
Feature classes can be associated with the parcel fabric if they are in different feature datasets or are standalone, but they must be in the same geodatabase as the parcel fabric.
The feature adjustment data model
Displacement vectors are stored in an adjustment vectors table (Fabric_Vectors) after a least-squares adjustment is run and the edit session is saved. All vectors stored for a single adjustment are tagged with a sequence ID, called an adjustment level. The adjustment level orders feature adjustments relative to other feature adjustments in the system. Each adjustment level has a corresponding date and time stamp and an associated job ID (stored in the Fabric_Adjustments table). The Fabric_Levels table stores associated feature class IDs, their source parcel fabric, and the most recent adjustment level applied to the feature class.
Because each set of displacement vectors is associated with an adjustment level, feature adjustments can be applied ad hoc. Since feature classes are tracked by their last adjustment level, previous displacement vectors are never reapplied and vector sets are always executed in sequence and not omitted.
Associating feature classes in a versioned environment
In a versioned environment, feature classes must be associated to the parcel fabric in the default version. You can associate feature classes in the Catalog tree or by using the Feature Adjustment command under the Parcel Editor menu on the Parcel Editor toolbar in an edit session on the default version. You would then need to reconcile any versions of the parcel fabric to pick up newly associated feature classes.