The Parcel Fabric - Exploring the Need for a New Parcel Data Model
The Parcel Fabric Exploring the Need for a New Parcel Data Model SERUG Conference April 26 - 28, 2010 Frank J. Conkling
Sunday, April 25, 2010
Parcel Mapping Techniques have Evolved
Sunday, April 25, 2010
Roman Taxing Maps
Sunday, April 25, 2010
County Tax Maps
Sunday, April 25, 2010
Introduction of GIS
Sunday, April 25, 2010
1st Attempt: Modeling the Map Lines and Text reproduce the map elements
Sunday, April 25, 2010
Look Familiar?
Sunday, April 25, 2010
2nd Attempt: The GIS Data Model
Sunday, April 25, 2010
Conceptually.... • Parcels are contiguous • No Gaps or Discrepancies in Boundaries • All Measurements are Equal • COGO information is captured and stored
Sunday, April 25, 2010
These Models are all missing Something...
Sunday, April 25, 2010
Where did the data come from?
Sunday, April 25, 2010
Information not stored in the model is lost • Source Documentation • Problems in mapping • Overlaps or Gaps • Adjustments made Sunday, April 25, 2010
The current process / models are not sustainable
Sunday, April 25, 2010
COGO Information • Bearing Lines - Bearing Basis • • • •
True North? Assumed North? Grid North? Magnetic North?
• Source Information • Rotation Angle • Adjustments Applied Sunday, April 25, 2010
Adjustments with current models, you can never go back
Sunday, April 25, 2010
Especially Dangerous with Insufficient Control
Sunday, April 25, 2010
What we really need is a way to track information on a feature level Record Level Metadata Sunday, April 25, 2010
The Case for a New Data Model
Sunday, April 25, 2010
Two Components to a Parcel Definition • Geometry • Spatial Location
Sunday, April 25, 2010
Geometry - The “What”
Sunday, April 25, 2010
Spatial Location - The “Where”
Sunday, April 25, 2010
Spatial Location is Not Absolute It is relative to other controlling elements, i.e. “monuments”
Sunday, April 25, 2010
Adjacent Inconsistencies • Different Bearings • Different Measurements • Different Linear Units
Sunday, April 25, 2010
We Need a Way to Track the Adjustments / Inconsistencies How can we maintain features if we cannot identify the actions performed on those features?
Sunday, April 25, 2010
Solution • Adopt a model that tracks the origins of both the geometry and the spatial locations
• Adopt a system that allows the tracking of adjustments
• Adopt a system that allows
incremental introduction of more accurate data
Sunday, April 25, 2010
Parcel Fabric Data Model
Sunday, April 25, 2010
Plans
Sunday, April 25, 2010
Plan Attributes
Sunday, April 25, 2010
Parcels
Sunday, April 25, 2010
Parcel Attributes
Sunday, April 25, 2010
Lines
Sunday, April 25, 2010
Line Attributes
Sunday, April 25, 2010
Corners
Sunday, April 25, 2010
Corner Attributes
Sunday, April 25, 2010
Control
Sunday, April 25, 2010
Control Attributes
Sunday, April 25, 2010
Adjustments • Uses Least Squares Adjustment to Control Points
• Requires Connection Lines • Lines have Accuracy Levels
Sunday, April 25, 2010
Adjustment Vectors • Created after least squares adjustment • Used to Adjust Associated Layers
Sunday, April 25, 2010
Associated Layers • Layers outside the Cadastral Fabric that can be adjusted to coincide with the Fabric.
Sunday, April 25, 2010
What Does it Take to Convert Existing Data?
Sunday, April 25, 2010
Structural Requirements • Naming is IMPORTANT • _arcs • _node • _polygon • All Parcels MUST have Lines • All Lines MUST have Corners • All Curves are True, Parametric Curves Sunday, April 25, 2010
Line Conversion Process • Multi Part to Single Part (Explode Tool) • Split Lines at Vertices • Planarize Lines • Calculate COGO Attributes • Create Connectivity Lines • Convert Curves • Check Topology Sunday, April 25, 2010
Parcel Polygon Conversion Process • Create Parcel Centroids (Feature to Points) • Run Spatial Join Tool to attribute Parcel_ID & Subtype
Sunday, April 25, 2010
Once Complete, • Unless the COGO attributes were
originally complete, the parcel geometry reflects MAPPED geometry, not Source geometry.
• Still missing attribution Sunday, April 25, 2010
Including..... • Attribution of Plans (Controlling Source Documents)
• Importation and Connection to Control Points • Subtyping of Parcel Polygons
Sunday, April 25, 2010
Remaining Issues • What are the Best Practices? • What Features are Best Modeled in the Fabric?
• Public Land Survey System? • Subdivisions? • Blocks? • Lots?
• Should Tax Parcels be stored in Cadastral Fabric?
Sunday, April 25, 2010
Incremental Adoption • Create a Cadastral Fabric using existing data
• Leave existing structure in place • Begin inputting new parcels in Cadastral Fabric
• Use Associated Layers to adjust existing structure
Sunday, April 25, 2010
Questions? Frank J. Conkling Panda Consulting www.pandaconsulting.com 561-691-3277
Sunday, April 25, 2010
Sunday, April 25, 2010
Parcel Mapping Techniques have Evolved
Sunday, April 25, 2010
Roman Taxing Maps
Sunday, April 25, 2010
County Tax Maps
Sunday, April 25, 2010
Introduction of GIS
Sunday, April 25, 2010
1st Attempt: Modeling the Map Lines and Text reproduce the map elements
Sunday, April 25, 2010
Look Familiar?
Sunday, April 25, 2010
2nd Attempt: The GIS Data Model
Sunday, April 25, 2010
Conceptually.... • Parcels are contiguous • No Gaps or Discrepancies in Boundaries • All Measurements are Equal • COGO information is captured and stored
Sunday, April 25, 2010
These Models are all missing Something...
Sunday, April 25, 2010
Where did the data come from?
Sunday, April 25, 2010
Information not stored in the model is lost • Source Documentation • Problems in mapping • Overlaps or Gaps • Adjustments made Sunday, April 25, 2010
The current process / models are not sustainable
Sunday, April 25, 2010
COGO Information • Bearing Lines - Bearing Basis • • • •
True North? Assumed North? Grid North? Magnetic North?
• Source Information • Rotation Angle • Adjustments Applied Sunday, April 25, 2010
Adjustments with current models, you can never go back
Sunday, April 25, 2010
Especially Dangerous with Insufficient Control
Sunday, April 25, 2010
What we really need is a way to track information on a feature level Record Level Metadata Sunday, April 25, 2010
The Case for a New Data Model
Sunday, April 25, 2010
Two Components to a Parcel Definition • Geometry • Spatial Location
Sunday, April 25, 2010
Geometry - The “What”
Sunday, April 25, 2010
Spatial Location - The “Where”
Sunday, April 25, 2010
Spatial Location is Not Absolute It is relative to other controlling elements, i.e. “monuments”
Sunday, April 25, 2010
Adjacent Inconsistencies • Different Bearings • Different Measurements • Different Linear Units
Sunday, April 25, 2010
We Need a Way to Track the Adjustments / Inconsistencies How can we maintain features if we cannot identify the actions performed on those features?
Sunday, April 25, 2010
Solution • Adopt a model that tracks the origins of both the geometry and the spatial locations
• Adopt a system that allows the tracking of adjustments
• Adopt a system that allows
incremental introduction of more accurate data
Sunday, April 25, 2010
Parcel Fabric Data Model
Sunday, April 25, 2010
Plans
Sunday, April 25, 2010
Plan Attributes
Sunday, April 25, 2010
Parcels
Sunday, April 25, 2010
Parcel Attributes
Sunday, April 25, 2010
Lines
Sunday, April 25, 2010
Line Attributes
Sunday, April 25, 2010
Corners
Sunday, April 25, 2010
Corner Attributes
Sunday, April 25, 2010
Control
Sunday, April 25, 2010
Control Attributes
Sunday, April 25, 2010
Adjustments • Uses Least Squares Adjustment to Control Points
• Requires Connection Lines • Lines have Accuracy Levels
Sunday, April 25, 2010
Adjustment Vectors • Created after least squares adjustment • Used to Adjust Associated Layers
Sunday, April 25, 2010
Associated Layers • Layers outside the Cadastral Fabric that can be adjusted to coincide with the Fabric.
Sunday, April 25, 2010
What Does it Take to Convert Existing Data?
Sunday, April 25, 2010
Structural Requirements • Naming is IMPORTANT • _arcs • _node • _polygon • All Parcels MUST have Lines • All Lines MUST have Corners • All Curves are True, Parametric Curves Sunday, April 25, 2010
Line Conversion Process • Multi Part to Single Part (Explode Tool) • Split Lines at Vertices • Planarize Lines • Calculate COGO Attributes • Create Connectivity Lines • Convert Curves • Check Topology Sunday, April 25, 2010
Parcel Polygon Conversion Process • Create Parcel Centroids (Feature to Points) • Run Spatial Join Tool to attribute Parcel_ID & Subtype
Sunday, April 25, 2010
Once Complete, • Unless the COGO attributes were
originally complete, the parcel geometry reflects MAPPED geometry, not Source geometry.
• Still missing attribution Sunday, April 25, 2010
Including..... • Attribution of Plans (Controlling Source Documents)
• Importation and Connection to Control Points • Subtyping of Parcel Polygons
Sunday, April 25, 2010
Remaining Issues • What are the Best Practices? • What Features are Best Modeled in the Fabric?
• Public Land Survey System? • Subdivisions? • Blocks? • Lots?
• Should Tax Parcels be stored in Cadastral Fabric?
Sunday, April 25, 2010
Incremental Adoption • Create a Cadastral Fabric using existing data
• Leave existing structure in place • Begin inputting new parcels in Cadastral Fabric
• Use Associated Layers to adjust existing structure
Sunday, April 25, 2010
Questions? Frank J. Conkling Panda Consulting www.pandaconsulting.com 561-691-3277
Sunday, April 25, 2010
