Advanced Editing: Rules-Based Topology in ArcEditor

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Advanced Editing Rules-Based Topology in
ArcEditor
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What is Topology?

• Historically, topology is the set of geometric
  relationships, determined mathematically, between
  connecting or adjacent features in a geographic
  dataset.
• e.g. FNODE, TNODE, LPOLY, RPOLY fields in a
  line (streets) ArcInfo coverage.

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What is Topology?

• With advances in GIS software, topology has been
  taking on more of a rule-based approach.
• In a geodatabase, a topology is a set of
  governing rules applied to feature classes that
  explicitly defines the spatial relationships that
  must exist between feature data.

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ArcView vs. ArcEditor

• Editing shared features is the same.
• ArcEditor Topology or Map Topology
• ArcView Map Topology
• ArcEditor Rule-based (Topology)
• ArcView Non rule-based (Map Topology)

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Topology and Feature Geometry

• Geometries involved in a topology

• Edges

- Line segments that define lines or polygons

• Nodes

- Points at the end of an edge
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Topology and Feature Geometry
Ways of sharing a geometry
Line features can share edges and nodes
Vertices define the shape of edges
Polygon features also share edges and nodes
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Why Use Topology

• Ensure data quality
• Easily edit shared boundaries and features
• More accurately model the real world

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Characteristics of a Topology

• Requires an ArcEditor or ArcInfo license.
• Can only be created for feature classes in a
  geodatabase. (not shapefiles)
• Feature classes participating in a topology must
  have the same spatial reference.
• A topology can only describe relationships
  between features within the same feature dataset
  of the same geodatabase.
• A feature class cannot participate in more than
  one topology.

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Properties of a Topology

• Topologies store three sets of parameters

Define the permissible spatial relationships
between features.
1) Rules
2) Cluster Tolerance
The distance at which vertices are
considered coincident.
3) Ranks
Control which features may be moved to
other features during validation.
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Properties of a Topology

• Topologies also maintain a feature layer that
  store

Dirty Areas

• Areas that have been
• edited since validation. Requires
• another validation to discover any
• errors.

Errors

• Violations of a topology rule detected during
  validation.

Exceptions

• Legitimate exceptions to a topology rule.

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Topology Workflow
Organize Data Setup the Topology Validate
Entire Topology Check for Errors Done Er
rors Exist Fix Errors/Mark as Exceptions Validat
e Topology of Dirty Areas
No Errors
Edit Data
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Building a Topology
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Organize your data
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• Start the Topology Wizard

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Building a Topology

• Name the new topology.

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Set the cluster tolerance. (in most cases, use
the default value)
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Building a Topology

• Determine which features you want to
  participate in the topology.

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Building a Topology
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• Set the number of allowed ranks.

Set the rank of each feature class.
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Begin adding rules to your topology.
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Building a New Topology

• Rules used by DDP

• Study Areas Must Not Overlap
• Study Areas Must Not Have Gaps
• Streets Must Not Self-Intersect
• Streets Must Not Self-Overlap
• Streets Must Not Have Dangles
• Streets Must Not Intersect or Touch Interior
• Schools Must be Properly Inside Study Areas.

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Building a Topology
The topology now appears in the geodatabase.
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• Review the Summary Report validate the
  topology.

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Reviewing a Topologys Properties

• Accessed through ArcCatalog or ArcMap

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Time for Exercise 1

• Follow the instructions in the handout.
• Stop at the end of Exercise 1.

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Review the Topology Workflow
Organize Data Setup the Topology Validate
Entire Topology Check for Errors Done Er
rors Exist Fix Errors/Mark as Exceptions Validat
e Topology of Dirty Areas
No Errors
Edit Data
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The Topology Toolbar
Topology Drop Down Menu
Show Shared Features
Map Topology Button
Validate Topology in Specified Area (AV Disabled)
Construct Features Button
Validate Topology in Current Extent (AV Disabled)
Planarize Lines Button (AV Disabled)
Validate Entire Topology (AV Disabled)
Topology Edit Tool
Fix Topology Error Tool (AV Disabled)
Error Inspector Button (AV Disabled)
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Validating a Topology

• You have several options

2) Using ArcMap (during an Edit Session).

1. Using ArcCatalog

c) Validate Entire Topology
b) Validate in Current Extent
a) Validate in Specified Area
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Identifying Topology Errors

• Use either the Error Inspector or the Fix
  Topology Tool to find and identify topology
  errors.

Error Inspector
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Identifying Topology Errors
Fix Topology Tool like a selection tool with
more functionality
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Fixing Topology Errors

• All topology fixes are done during an edit
  session in ArcMap.
• Select an error with the Error Inspector or Fix
  Topology Tool and apply one of the pre-described
  fixes.

• Different rules have different fixes available.
  Lets take a look

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Fixing Topology Errors in Study Areas
Fixing Overlaps
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Fixing Topology Errors in Study Areas

• Fixing Gaps

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Fixing Topology Errors in Streets

• Intersect or Touch Interior, Dangles,
  Self-Intersections, Self-Overlaps

Dangles
Intersect or Touch Interior
(Or select the features and click
Planarize Lines )
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Fixing Topology Errors in Streets
Self-Overlaps Self-Intersections
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Fixing Topology Errors in Schools

• Schools must be properly inside Study Areas

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Marking Errors as Exceptions

• In some cases you will have errors that break a
  topology rule, but are legitimate exceptions to
  that rule.

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Time for Exercise 2

• Follow the instructions in the handout
• Stop at the end of Exercise 2

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Advanced Editing in ArcEditor
Questions?
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Other Topology Editing

• Moving shared features

• Using features in one feature class to construct
• features in other feature classes

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Moving Shared Features
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Constructing Features from Featuresin Different
Feature Classes
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Advanced Editing in ArcEditor
Questions?