Edges

Edges represent a part of a line or boundary of a polygon, for example, a section of a road or county boundary.

The path of a line or polygon is a series of directed edges, with references to indicate the order of the connection. Each directed edge is flagged to indicate if it will be used in the same direction of the geometry, or reversed.

Every edge has a node at the start and a node at the end. If the line is made up of several edges, the nodes at the start and end of each edge are shared.

If two polygons (such as two buildings) share part of the boundary, the edges are shared. Sharing edges identifies the co-linearity of two features and ensures that no slivers are introduced between the edges.

Note: If the boundaries are close to touching, these will be snapped to share the edge.

In planar topology, edges never overlap. If any data is made up of overlapping or crossing lines, the edges are split and nodes are formed at the intersections.

In network topology, edges can overlap depending on the snapping type.

Edges exist in the system datastore as sys:edge.

An edge has the following references:

• sys: node_to_edge - Obtains nodes on either sides of an edge
• sys: area_to_edge (polygons) - Finds polygons that use an edge as the boundary
• sys: line_to_edge (lines) - Finds lines that use an edge as the boundary