Geodatabase Topology Editing Sherry Fu CE697v Final project Dec. 08, 2006

Basics of Topology Objects Creating a geodatabase topology –Cluster tolerance –Ranks –Topology rules Dirty areas Validating a topology Managing errors and exceptions

Topology in the Geodatabase Spatial integrity of data – Finds topology errors (user sets the rules) – Fix with edit and topology tools Coincidence based topology – Snaps feature vertices –Single or multiple feature classes Feature topology is not stored – Only properties, errors, and exceptions are stored

Creating a Topology Topology properties – Participating feature classes – Cluster tolerance – Ranks – Topology rules

Cluster Tolerance Cluster tolerance should be very small A distance within which all geometry is considered coincident, or identical in location! (1 cm / 100 cm in a meter) / 10 (order of magnitude) = 0.001ArcGIS 9.2 : (1 cm / 100 cm in a meter) / 10 (order of magnitude) = 0.001

Ranks Control how vertices move during validation Lower-ranked vertices move to higher- ranked vertices –Ranks: 1 (highest) to 50 (lowest) –Set ranks between feature classes

Topology Rules Set as properties of the topology, 25 rules available –Between features on a single feature class –Between feature classes –Between subtypes

Validation Not Validated –Dirty areas exist Validated – Errors Exist –All dirty areas have been validated and errors were found Validated – No Errors –All dirty areas have been validated and no errors were found

Dirty Areas Areas in the dataset that have not been validated – Entire extent is “dirty” when topology is first created – May contain existing or undiscovered errors – Edits create dirty areas

Topology Editing Tools Validating a Topology Topology Errors Managing Errors

Overview Create a topology Validate the topology Examine topology errors Perform edits to fix topology errors