What is Topology?

Topology in SIS Desktop 9 establishes relationships between geographical elements in a map dataset.

This is particularly helpful if the elements share any geometry. The topological relationship ensures all related elements are edited simultaneously.

The basic building blocks (or primitives) of a topological dataset are Links and Nodes.

  • A Link is a topological LineString item storing relationship data with other topological items.
  • A Node item is a topological Point item used to form the junction of two or more Links (or the end of a Link if it is only partially connected).

Together links and nodes are used to create a network or mesh.

  1. TopoLineStrings represent routes along a sequence of Links
  2. TopoPolygons represent the Polygons enclosed by a sequence of links.
  3. TopoPoints can be created at node locations to represent entities which exist at the node location.

Note: Topology is only supported in Cadcorp Base Dataset (*.bds) or Cadcorp Item Database (*.idb) formats.

Examples of topology

Here are some examples to better illustrate the principle of topology.