Parcel Data Models for Parcel Data Models for the Geodatabasethe Geodatabase

Indiana GIS Conference 2012

WelcomeWelcome

Joyce WestGIS Account ManagerThe Sidwell Company

Presentation AgendaPresentation Agenda

Parcel-based GIS editing to maintain common boundaries with:◦Polygon Model◦Coincident Boundary Model◦Parcel Fabric Model

Some backgroundSome background

Coverage Format◦Legacy Esri format◦Contain features organized into feature classes-

arc, node, label point, polygon, and annotation◦Support shared geometry and polygon

adjacency◦Maintain topology

Some backgroundSome background

Shapefile format◦Supports simple point, line, area features◦Non-topological geometry◦Attributes have one-to-one relationship with

shapes◦Common for data sharing

Some backgroundSome background

Geodatabase format◦Data storage and management◦Uses standard RDBMS products

MS Access MS SQL Server Oracle

◦Map graphics and attributes stored together◦Supports relationships and business rules◦Supports multi-user access and editing

Geodatabase EditingGeodatabase Editing

Appropriate software to support◦Advanced Cartography ◦Coordinate Geometry◦Create and edit feature relationships

i.e. feature linked annotation◦Topology rules and fix operations◦Multi-user editing◦Distributed geodatabases

Polygon ModelPolygon Model

The polygon model is a simple, straightforward GIS data model where map features exist as separate polygons or data layers.

Polygon ModelPolygon Model

Store map features as separate polygons such as parcels, subdivisions, corporate limits

Edit lines or edit polygons directlyMay use cut and paste operationsPlacement of edits is user-controlledUse map topology tools to maintain

alignments in personal or file geodatabaseRun topology checks to insure data integrity

Features on top of

features on top of

features

Can result in this…

Coincident Boundary ModelCoincident Boundary Model

The Coincident Boundary Model is based on the concept of using common geography to represent multiple features. To accomplish this, a linear feature class is created in the geodatabase that stores all boundary features.

Common Coincident Common Coincident BoundariesBoundaries

Cadastral/Ownership Parcel Line Lot Line Subdivision Road Right-of-Way City/State/County boundary

EasementsZoningGovt Districts

Tax DistrictsCensus data

Coincident Boundary ModelCoincident Boundary Model

Map features occupy the same place in the same plane

Map features that are common to two or more data layers

User selects which features will participate in this model

Assign multiple feature identities or boundary types

Coincident Boundary ModelCoincident Boundary Model

Establish a hierarchy to symbolize map features

Edit map features as lines, often just by changing a tag

After edits, polygons can easily be updated by querying and extracting lines attributed with the appropriate features from the editable layer

Coincident Boundary ModelCoincident Boundary Model

Coincident Boundary ModelCoincident Boundary Model

The Parcel Fabric ModelThe Parcel Fabric Model

The Parcel Fabric is a data model and geodatabase maintenance environment developed by Esri. The Parcel Fabric is a modeling solution that stores cadastral information as a continuous surface of connected parcels.

What is The Parcel Fabric?What is The Parcel Fabric?

• A specialized grouping of core Arc feature classes• Control points• Line points• Points• Lines• Polygons (Parcel, Lot, etc…)

• Detailed Relationships are tracked between them

Fabric Sub LayersFabric Sub Layers

Control Points ◦Used to run the Least

Squares AdjustmentLine Points

◦Track intersections from adjacent parcels that don’t require a “Node” pointPoints

◦Track “Node” points for a given parcel◦Often called “Parcel Points”

Fabric Sub LayersFabric Sub LayersLines

◦Boundary lines of Fabric polygons

◦Can be categorized to track additional line types

Fabric RelationshipsFabric Relationships

Lines to Points◦Every Fabric line know it’s “from” and

“to” Fabric point

Lines for every boundary◦Every Fabric line knows the parcel

polygon it defines the boundary of

Fabric Sub LayersFabric Sub LayersParcels

◦Parcel Polygon◦Can be categorized to

track multiple polygon types

Results in overlapping geometry

Data Integrity and Data Integrity and RedundancyRedundancy

Topological accuracy is ensured◦Joining parcels with shared points

Each parcel has its own set of lines◦Overlapping for a common boundary◦More lines define relatively fewer points

012 31 32

33 34

9 Points16 Lines

Parcel Fabric EditingParcel Fabric Editing

Parcel editor toolbar in core Editing workflows allow easy input of

fabric featuresSimple merge and split functionsGroups transactions by Plans

Parcel Fabric BenefitsParcel Fabric Benefits

Improves data accuracy ◦least squares adjustments

Adjusts related featuresAutomatically stores historical geometryTopology rules can be established

between features and the fabric

LGIMLGIM

Local Government Information Model◦Organization of data◦Extends use of GIS◦Easy to deploy Maps & Apps

Parcel Fabric Layer

In SummaryIn Summary

Polygon Model ◦ Run topology checks◦ Relies on editor vigilance◦ May take more steps

Coincident Boundary Model◦ One feature – multiple representations◦ Keeps polygon edges aligned◦ Efficient editing

Parcel Fabric Model◦ Interconnected and related point, line and polygon

features◦ Automatically stores history◦ Uses edit wizards and spatial adjustment

Thank youThank youJoyce West

GIS Account ManagerThe Sidwell Company | www.sidwellco.com