1. Advanced Editing: Rules-Based Topology in ArcEditor

2. What is Topology?
Topology describes the spatial relationships between adjacent features, and uses x, y coordinates to identify the location of a particular point, line, or polygon. Using such data structures enforces planar relationships, and allows GIS specialists to discover relationships between data layers, to reduce artifacts from digitization, and to reduce the file size required for storing the topological data.

3. 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.

4. 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.

5. 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)

6. 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

7. 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

8. Why Use Topology Ensure data quality
Easily edit shared boundaries and features
More accurately model the real world

9. 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.

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

11. Properties of a Topology
Topologies also maintain a feature layer that store:
Areas that have been
edited since validation. Requires
another validation to discover any
errors.
Dirty Areas
Errors
Violations of a topology rule detected during validation.
Exceptions
Legitimate exceptions to a topology rule.

12. Topology Workflow Organize Data Setup the Topology
Validate Entire Topology
Check for Errors
Done
Errors Exist
Fix Errors/Mark as Exceptions
Validate Topology of Dirty Areas
No Errors
Edit Data

13. Building a Topology 1
Organize your data 2
Start the Topology Wizard

14. 3 4 Building a Topology Name the new topology.
Set the cluster tolerance. (in most cases, use the default value) 4

15. Building a Topology
Determine which features you want to participate in the topology. 5

16. 6 7 8 Building a Topology Set the number of allowed ranks.
Set the rank of each feature class. 8
Begin adding rules to your topology.

17. 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.

18. 10 9 Building a Topology The topology now appears in the geodatabase.
Review the Summary Report & validate the topology.

19. Reviewing a Topology’s Properties
Accessed through ArcCatalog or ArcMap

20. Time for Exercise 1 Follow the instructions in the handout.
Stop at the end of Exercise 1.

21. Review the Topology Workflow
Organize Data
Setup the Topology
Validate Entire Topology
Check for Errors
Done
Errors Exist
Fix Errors/Mark as Exceptions
Validate Topology of Dirty Areas
No Errors
Edit Data

22. 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)
Planarize lines: You can split selected lines that intersect each their intersections.
Topology Edit Tool
Fix Topology Error Tool
(AV Disabled)
Error Inspector Button
(AV Disabled)

23. Validating a Topology You have several options:
Using ArcCatalog
2) Using ArcMap (during an Edit Session).
c) Validate Entire Topology
b) Validate in Current Extent
a) Validate in Specified Area

24. Identifying Topology Errors
Use either the Error Inspector or the Fix Topology Tool to find and identify topology errors.
Error Inspector:

25. Identifying Topology Errors
Fix Topology Tool:
like a selection tool with more functionality

26. 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…

27. Fixing Topology Errors in Study Areas
Fixing Overlaps:

28. Fixing Topology Errors in Study Areas
Fixing Gaps:

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

30. Fixing Topology Errors in Streets
Self-Overlaps & Self-Intersections:

31. Fixing Topology Errors in Schools
Schools must be properly inside Study Areas:

32. Marking Errors as Exceptions
In some cases you will have errors that break a topology rule, but are legitimate exceptions to that rule.

33. Time for Exercise 2 Follow the instructions in the handout
Stop at the end of Exercise 2

34. Advanced Editing in ArcEditor
Questions?

35. Other Topology Editing
Moving shared features
Using features in one feature class to construct
features in other feature classes

36. Moving Shared Features

37. Constructing Features from Features in Different Feature Classes

38. Advanced Editing in ArcEditor
Questions?