# Advanced Editing: Rules-Based Topology in ArcEditor

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Advanced Editing: Rules-Based Topology in ArcEditor Slide 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.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. Slide 3 What is Topology? Historically, topology is the set of geometric relationships, determined mathematically, between connecting or adjacent features in a geographic dataset.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.e.g. FNODE#, TNODE#, LPOLY#, RPOLY# fields in a line (streets) ArcInfo coverage. Slide 4 What is Topology? With advances in GIS software, topology has been taking on more of a rule-based approach.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.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. Slide 5 ArcEditor ArcView vs. ArcEditor Editing shared features is the same.Editing shared features is the same. ArcEditor Topology or Map Topology ArcView Map Topology ArcEditor Rule-based (Topology)ArcEditor Rule-based (Topology) ArcView Non rule-based (Map Topology)ArcView Non rule-based (Map Topology) Slide 6 Topology and Feature Geometry Geometries involved in a topology: Nodes Edges- Line segments that define lines or polygons - Points at the end of an edge Slide 7 Topology and Feature Geometry Ways of sharing a geometry: Line features can share edges and nodes Polygon features also share edges and nodes Vertices define the shape of edges Slide 8 Why Use Topology Ensure data qualityEnsure data quality Easily edit shared boundaries and featuresEasily edit shared boundaries and features More accurately model the real worldMore accurately model the real world Slide 9 Characteristics of a Topology Requires an ArcEditor or ArcInfo license.Requires an ArcEditor or ArcInfo license. Can only be created for feature classes in a geodatabase. (not shapefiles)Can only be created for feature classes in a geodatabase. (not shapefiles) Feature classes participating in a topology must have the same spatial reference.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 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.A feature class cannot participate in more than one topology. Slide 10 Properties of a Topology Topologies store three sets of parameters:Topologies store three sets of parameters: Control which features may be moved to other features during validation. Define the permissible spatial relationships between features. The distance at which vertices are considered coincident. 1) Rules 2) Cluster Tolerance 3) Ranks Slide 11 Properties of a Topology Topologies also maintain a feature layer that store:Topologies also maintain a feature layer that store: Exceptions Errors - Areas that have been edited since validation. Requires another validation to discover any errors. Dirty Areas - Violations of a topology rule detected during validation. - Legitimate exceptions to a topology rule. Slide 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 Slide 13 Building a Topology Start the Topology Wizard Organize your data Slide 14 Building a Topology Name the new topology. Set the cluster tolerance. (in most cases, use the default value) Slide 15 Building a Topology Determine which features you want to participate in the topology. Determine which features you want to participate in the topology. Slide 16 Building a Topology Set the number of allowed ranks. Begin adding rules to your topology. Set the rank of each feature class. Slide 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. Slide 18 Building a Topology Review the Summary Report & validate the topology. The topology now appears in the geodatabase. Slide 19 Reviewing a Topologys Properties Accessed through ArcCatalog or ArcMapAccessed through ArcCatalog or ArcMap Slide 20 Time for Exercise 1 Follow the instructions in the handout.Follow the instructions in the handout. Stop at the end of Exercise 1.Stop at the end of Exercise 1. Slide 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 Slide 22 The Topology Toolbar Topology Drop Down Menu Map Topology Button Construct Features Button Planarize Lines Button (AV Disabled) Topology Edit Tool Show Shared Features Validate Topology in Specified Area (AV Disabled) Validate Topology in Current Extent (AV Disabled) Validate Entire Topology (AV Disabled) Fix Topology Error Tool (AV Disabled) Error Inspector Button (AV Disabled) Slide 23 Validating a Topology You have several options:You have several options: 1)Using ArcCatalog 2) Using ArcMap (during an Edit Session). a) Validate in Specified Area b) Validate in Current Extent c) Validate Entire Topology Slide 24 Identifying Topology Errors Use either the Error Inspector or the Fix Topology Tool to find and identify topology errors.Use either the Error Inspector or the Fix Topology Tool to find and identify topology errors. Error Inspector: Slide 25 Identifying Topology Errors Fix Topology Tool: like a selection tool with more functionality Slide 26 Fixing Topology Errors All topology fixes are done during an edit session in ArcMap.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.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 lookDifferent rules have different fixes available. Lets take a look Slide 27 Fixing Topology Errors in Study Areas Fixing Overlaps: Slide 28 Fixing Topology Errors in Study Areas Fixing Gaps: Slide 29 Fixing Topology Errors in Streets Intersect or Touch Interior, Dangles, Self-Intersections, Self-OverlapsIntersect or Touch Interior, Dangles, Self-Intersections, Self-Overlaps Intersect or Touch Interior: Dangles: (Or select the features and click Planarize Lines ) Slide 30 Fixing Topology Errors in Streets Self-Overlaps & Self-Intersections: Slide 31 Fixing Topology Errors in Schools Schools must be properly inside Study Areas:Schools must be properly inside Study Areas: Slide 32 Marking Errors as Exceptions In some cases you will have errors that break a topology rule, but are legitimate exceptions to that rule. Slide 33 Time for Exercise 2 Follow the instructions in the handoutFollow the instructions in the handout Stop at the end of Exercise 2Stop at the end of Exercise 2 Slide 34 Advanced Editing in ArcEditor Questions? Slide 35 Other Topology Editing Moving shared featuresMoving shared features Using features in one feature class to constructUsing features in one feature class to construct features in other feature classes Slide 36 Moving Shared Features Slide 37 Constructing Features from Features in Different Feature Classes Slide 38 Advanced Editing in ArcEditor Questions?