Topology editing is an editing mode. When enabled, it creates a temporary topology based on all visible 2D line and polygon layers. In this mode, editing objects maintains topological continuity between them.

You can enable topology editing by checking the box in front of Topology Editing in the Features tab, Map Editing group. This will automatically enable multi-layer editing and turn on the editing status of all visible and editable layers in the map. During editing, different layers may be modified simultaneously.

Layers with read-only data sources or invisible layers cannot participate in topology editing.

Special tools for topology editing are provided: Align Edges, Trim, and Topology Edit Node. These three editing tools are only available when topology editing is enabled. In addition, when topology editing is enabled, moving topological edges and nodes is supported while maintaining topological continuity. When topology editing is not enabled, it is in normal moving mode and does not maintain topological continuity.

To help you better understand the topology editing function, the following provides a brief explanation of related concepts:

• Topological Nodes: Nodes are the intersection points of geometries in the map.
• Topological Edges: Topological edges are the shared linear boundaries between geometries. A topological edge consists of two topological nodes.
• Topological Graph: A topological graph consists of nodes and topological edges and is used to represent the topology of objects in the map. When topology editing is enabled, the topological graph is displayed on layers within the current map extent.

This chapter introduces the following content:

• Move: Describes how to move topological edges and nodes.
• Topology Edit Node: Describes how to use the Topology Edit Node tool to move, add, or delete object nodes.
• Trimming: Describes how to use the Trim tool to reshape topological edges.
• Align Edges: Describes how to reshape a topological edge so that it matches and coincides with another edge sharing two common topological nodes.