3 - Topological polygon#

Algorithm ID: hedgetools:topologicalpolygon

This tool splits polygons using the:

polygon layer created by Topological Arc
line and point layer created by Topological Node.

Polygons are split at every non-extremity node (i.e., nodes with a degree greater than 1). The primary key (PK) and foreign key (FK) fields in the related layers are automatically updated to reflect the new topology.

Warning

The algorithm checks whether the polygon–arc relationship is one-to-one at the end of the process. A warning is raised for polygons that contain either no arc or multiple arcs.

Proceeding without correcting or removing these errors may cause issues in following steps.

When correcting these issues, make sure to update all primary key (PK) and foreign key (FK) fields across the related layers, or run the Update Link algorithm afterwards.

Parameters#

Label	Name	Type	Description
Input polygon layer	`INPUT_POLY`	[vector: polygon]	Polygon vector layer with a `pid` field to be split by the topological arcs.
Input arc layer	`INPUT_ARC`	[vector: line]	Line vector layer with `pid`, `eid`, `src_vid`, `tgt_vid` fields representing the topologcal arcs.
Input node layer	`INPUT_NODE`	[vector: point]	Point vector layer with a `vid` field representing line junctions and extremities.
Node type	`NODE_TYPE`	[field: string] Default: `node_type`	Field storing the node type.
Output polygon layer	`OUTPUT_POLY`	[vector: polygon] Default: `[Create temporary layer]`	Output polygon vector layer.
Output arc layer	`OUTPUT_ARC`	[vector: line] Default: `[Create temporary layer]`	Output line vector layer.

Outputs#

Label	Name	Type	Description
Output polygon layer	`OUTPUT_POLY`	[vector: polygon]	Split polygon vector layer.
Output arc layer	`OUTPUT_ARC`	[vector: line]	Line vector layer with updated `pid` and `eid` fields.