Topology of vector datasets

Topology of vector datasets

• • topology describes the spatial relationships of points, nodes, and lines, and when lines “close” the polygons interior vs exterior.
  • In the diagrams below 1 and 2 have the same topology but different geometry and 1 and 3 have the same geometry but different topology

    

  • The topology is broken or leaky when polygons won’t “close” with digitizing errors

• • digitizing errors can be avoided by having a “snapping tolerance” that causes points you want to become nodes to automatically align to one another (to the required seven decimal places !), while still allowing polygon or polyline traverses or chains.

Edited by NDB, January 13, 2025