About migrating parcel data using geodatabase topology

This topic applies to ArcEditor and ArcInfo only.

In ArcGIS 10 a topologically clean, validated set of parcel feature class data can be migrated directly into the parcel fabric. Prior to ArcGIS 10, existing parcel datasets needed to be formatted into fabric source datasets to be migrated into a parcel fabric.

In this approach, a geodatabase topology is created in a feature dataset containing a feature class of parcel lines; a feature class of parcel polygons; and, optionally, a feature class of points (parcel corners). The topology is validated against a required set of rules, and once the topology is clean, the data can then be migrated to a parcel fabric using the Load A Topology To A Parcel Fabric geoprocessing tool.

Topology is the model used to describe how features share geometry and is the mechanism for establishing and maintaining spatial relationships between features.

Learn more about Topology in ArcGIS

If your existing parcel data consists only of polygons, you can convert the polygons to lines using the Polygon To Line geoprocessing tool.

Topology rules

When a topology is validated, features participating in the topology are validated against a set of defined rules, and violations of the rules are treated as errors.

When using the Load A Topology To A Parcel Fabric geoprocessing tool to migrate line and polygon features to a parcel fabric, the following set of topology rules is required:

1. [Line feature class] Must Be Covered By Boundary Of [Polygon feature class].
2. [Line feature class] Must Not Self-Overlap.
3. [Line feature class] Must Not Self-Intersect.
4. [Line feature class] Must Be Single Part.
5. [Line feature class] Must Not Intersect Or Touch Interior.
6. [Polygon feature class] Boundary Must Be Covered By [Line feature class].

Errors resulting from the [Polygon feature class] Boundary Must Be Covered By [Line feature class] rule can be marked as exceptions. This is so that connection lines and unclosed parcels can be migrated from source data. Connection lines are lines that connect to control points or lines that connect blocks of parcels. Unclosed parcels are polylines that are used to model parcel types such as street centerlines.

A topology can be validated in ArcCatalog or in ArcMap. In ArcCatalog, the entire dataset is validated. In ArcMap, you can choose to validate a subset of the data by using the Validate Topology in Current Extent or Validate Topology in Specified Area tools located on the Topology toolbar.

Once a topology is validated, any violations of the topology rules or errors are symbolized and displayed in the topology layer in ArcMap. Topology errors are symbolized by points, lines, and polygons.

Topology layer with errors

Topology errors can also be viewed in the Error Inspector dialog box located on the Topology toolbar. The Error Inspector lists the topology errors in the current visible extent. You can also choose to list all topology errors. Errors are listed by the rule that was violated.

Topology Error Inspector

Learn more about the Error Inspector dialog box

Once the validated topology is clean with no errors, the feature class data is ready for migration. The Load A Topology To A Parcel Fabric tool is located in ArcCatalog (or the Catalog window in ArcMap) under Toolboxes > System Toolboxes > Parcel Fabric Tools.tbx > Data Migration.

Migrating parcel line and polygon features

The Load A Topology To A Parcel Fabric geoprocessing tool is performance intensive, and the number of parcels you can load will depend on your computer configuration and memory availability. When working with a large parcel dataset, you can either split up the dataset into manageable sections of data or load selections of polygons or lines.

The tool can use either parcel line or the parcel polygon features as input; however, both polygon and line feature classes are required for the load to complete successfully.

Load A Topology To A Parcel Fabric geoprocessing tool

If there is a selection present on the input polygon or line feature class, only the selected features will be loaded into the fabric. When using a selection on lines, parcels will be imported as unclosed if all the lines are not selected for a particular parcel boundary. If lines are not unclosed parcel boundaries and represent, for example, dangling connection lines, the line feature should have a Category attribute, and the attribute value should be set to 3 (instead of 0 for the Boundary line category). Dangling lines should be marked as exceptions to the rule "Must Be Covered By Boundary Of". You will need to create a Category field on your parcel line feature class.

Note:

Any additional user-defined attributes existing on the polygon and line feature classes will also be migrated to fabric parcels and lines provided that the same attributes exist on the parcel fabric tables.

See how to add additional attributes to parcel fabric tables

Note:

There is a limit to the number of lines a parcel can have to be successfully migrated into a parcel fabric. Parcels containing more than five thousand lines or segments can not be migrated by the topology loader tool. Typically, parcels that have natural boundaries have a large number of boundary segments.

Steps for migrating parcel line and polygon feature class data using the topology loader

The following steps can be used as a guide for migrating sections of parcel feature class data to the fabric:

1. Create a new topology in the feature dataset containing your existing parcel polygon and line feature classes.
2. Add the required set of rules described above to the topology.
3. In ArcMap, load the target fabric and the topology containing both the parcel polygon feature class and the parcel line feature class.
4. Zoom to the area of data that you would like to load into the fabric.
5. Start editing and validate the current map extent of your data. (Click the Validate Topology In Current Extent button on the Topology toolbar).
6. Fix any errors resulting from the topology validation. The lines or polygons that you select and load into the fabric must be clean and have no errors.
7. Stop editing and save your edits.
8. Using the Select By Rectangle tool on the Tools toolbar and select the polygons that will be loaded into the fabric. (You can also select lines instead.)
9. On the Catalog window, open the Load A Topology To A Parcel Fabric geoprocessing tool located under Toolboxes > System Toolboxes > Parcel Fabric Tools.tbx > Data Migration.
10. Specify the fabric loaded in the map as the target parcel fabric and the parcel polygon feature class as the Input (Topology) Feature Class. Enter any other necessary parameters for your migration and run the tool.

    Load selected polygon features into the fabric.

    Once the load is complete, the migrated fabric parcels are displayed in ArcMap.

    

11. Repeat the steps above to migrate an additional selection of parcel feature class data.

Migrating point features (optional)

You would migrate existing point features to the parcel fabric when you need your user-defined attribute values on those points to be reflected in corresponding points in the parcel fabric. As with polygon and line features, if there is a selection on the point feature class layer, only the selected points will be migrated.

Populating system attributes

During migration, you can populate system attributes on the fabric parcels and fabric lines tables if the same attributes are created and populated in your line and polygon feature classes. For example, you will need a Type attribute on both your polygon and line feature classes to migrate across parcel and line types. In another example, you will need a Category attribute on your lines feature class if you want to migrate lines as connection lines.

Attributes on the lines feature class

The following attributes can be created on your lines feature class, and their values will be reflected in corresponding system attributes in the fabric lines table:

Field name	Field type	Description
Category	Long integer	The line category (for example, boundary line or connection line)
Calculated	Long integer	True if dimensions are inverted from line shape geometry
Type	Long integer	Used for custom subtypes on the lines (for example, road frontage, back lot line)
AccuracyCat (or ACCURACY)	Long integer	The accuracy level of the line

A table listing the optional fields that you can have on your source parcel lines

Tip:

If you have no COGO attributes on some or all of your source parcel lines, the data migration process will automatically generate COGO attributes for you by inverting the line shapes. If you have a Calculated field on your source parcel lines, you can set the field value to True for all lines with generated COGO attributes. This will help you distinguish between the lines in your parcel fabric that have inverted COGO dimensions and the lines that have COGO dimensions that match the record.

The Type field is used when you have your own custom subtypes on your source parcel lines. You will need to create the same subtype on the system Type field of the parcel fabric lines table for your subtypes to migrate successfully.

If any of the optional fields are missing on your source parcel lines, corresponding fields in the parcel fabric lines table will have the following values:

• No Category field: Category = Boundary line (All lines in your parcel fabric will be set to the Boundary line category.)
• No Calculated field: Calculated = NULL
• No Type field: Type = NULL
• No AccuracyCat field: Accuracy level = 3

Attributes on the polygon feature class

The following attributes can be created on your polygon feature class, and their values will be reflected in corresponding system attributes in the fabric parcels table:

Field name	Field type	Description
Area (or StatedArea)	Double	The parcel area as stated on the plan or record of survey
PlanName (or Plan)	String	The name of the plan or record of survey
AccuracyCat (or Accuracy)	Long integer	The accuracy level of the parcel
Type	Long integer	Used for custom subtypes on the polygons (for example, commercial/residential parcel)
Historical	Long integer	True (1) if the parcel is historic
LegalStart (or LegalStartDate)	Date	The date of the legal transaction that created the parcel (in other words, the date on the record of survey)
LegalEnd (or LegalEndDate)	Date	The date of the legal transaction that retired the parcel, that is, the date of the record of survey of the replacing parcel

A table listing the optional fields on your source parcel polygons

If any of the optional fields are missing on your source parcel polygons, corresponding fields on the parcel fabric parcels table will have the following values:

• No Area field: StatedArea = the area of the polygon shape geometry
• No PlanName field: Plan = the name of the feature class being migrated (For example, if there was no PlanName field on the AlachuaCounty_polygon table, the plan name for all parcels would be AlachuaCounty.)
• No AccuracyCat field: Accuracy of all parcels = 3 (default)
• No Type field: Type = NULL
• No LegalStart field: LegalStartDate = NULL
• No LegalEnd field: LegalEndDate = NULL
• No Historical field: Historical = NULL, which is also false