Last modified August 17, 2007
Print all topics in : "Editing topology"
NOTE: You can create simple, temporary topological relationships between features in ArcView. Creating or editing geodatabase topology requires an ArcEditor or ArcInfo license.
Topology is used most fundamentally to ensure data quality and allow your geodatabase to more realistically represent geographic features. A geodatabase provides a framework within which features can have behavior such as subtypes, default values, attribute domains, validation rules, and structured relationships to tables or other features. This behavior enables you to more accurately model the world and maintain referential integrity between objects in the geodatabase. Topology may be considered an extension of this framework for behavior that allows you to control the geometric relationships between features and maintain their geometric integrity. Unlike other feature behavior, topology rules are managed at the level of the topology and dataset, not for individual feature classes.
Different people work with topology in different ways, depending upon their role in an organization and its GIS design and management work flow.
Initially, creating a topology requires a geodatabase designer. A topology organizes the spatial relationships between features in a set of feature classes. The designer analyzes an organization's data modeling needs, identifies the key topological relationships required in the geodatabase, and defines the rules that will constrain different features' topological relationships.
Once the participating feature classes have been added to the topology and the rules defined, the topology is validated. Data quality managers use the topology tools to analyze; visualize; report; and, where necessary, repair the spatial integrity of the database after it is initially created, as well as after editing. Topology provides these users with a set of validation rules for the topologically related features. It also provides a set of editing tools that let users find and fix integrity violations.
As the geodatabase is used and maintained, new features are added, and existing features are modified. Data editors update features in the geodatabase and use the topology tools to construct and maintain relationships between features within the constraints imposed by the database designer. Depending on the work flow of the organization, the topology may be validated after each edit session or on a schedule.
You can also impose a map topology on your data. A map topology allows you to simultaneously edit simple features that overlap or touch each other. You can create a map topology with an ArcView license (creating a geodatabase topology requires an ArcInfo or ArcEditor license) and apply a map topology to simple features in a shapefile or to simple feature classes in a geodatabase.
When you create a topology, you specify the feature classes that participate in the topology. These feature classes may have point, line, or polygon features in them. In the topology, the geometric relationships are between the parts of the features rather than the features themselves. Polygons in a topology have: