2D Topology Preprocessing
Feature Description
Before validating topology relations using topology datasets, it's necessary to perform topological preprocessing on the target data. This process adjusts problematic data within tolerance ranges. Skipping preprocessing may lead to erroneous topology validation results. 2D topology preprocessing methods include: node insertion, node-to-node snapping, and polygon orientation adjustment.
Feature Entry
- Data tab->Topology group->Topology Preprocessing drop-down button->2D Topology Preprocessing.
Steps
- Click Data -> Topology -> Topology Preprocessing -> 2D Topology Preprocessing.
- Click the Add button on the toolbar to include datasets requiring preprocessing in the dataset list box.
- Set the Tolerances value, which defines the distance threshold for topological adjustments. Nodes/lines within this range are considered coincident. For example: nodes from different lines within tolerance are merged; points within tolerance from lines are considered on the line. Detailed explanations can be found in Tolerance Description.
- Node Snap: Snaps nodes within tolerance range (adjusting coordinates to match). "Nodes" include point features and vertices of line/polygon features. When checked, select a reference dataset to use its node positions as snapping reference. Removes redundant adjacent points after snapping. Processing effects:
Before preprocessing After preprocessing - Insert between vertex and arc: When enabled, inserts perpendicular foot points on lines when point-to-line distances are within tolerance.
Before preprocessing After preprocessing - Insert for arc intersections: Inserts nodes at line intersections while maintaining original data orientation.
Before preprocessing: 
After preprocessing: 
- Adjust polygon direction: Adjusts polygon boundaries to standard orientation - outer boundaries clockwise, holes counter-clockwise, islands clockwise.
After preprocessing - Click OK to execute preprocessing.
Related Topics