Vector topology cleaning

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Q: How can I patch to fitting area maps with have been digitized separately and correct the topology? I observe that the shared polygon boundaries do not perfectly match...

Polygon vector map with topology problems

A: You can use v.clean for this.

Tools to consider:

  • TBD
  • ...

Q: How about self-intersecting lines and boundaries?

A: In the GRASS topological model self-intersecting lines are allowed, self-intersecting boundaries are not. Self-intersecting lines are ok e.g. for v.net modules, e.g. to represent a bridge of a secondary road over a highway.

Note: There are some modules that do not like self-intersecting lines, e.g with v.buffer problems are expected.


Polygon import from SHAPE file:

Overlayed polygons after import from SHAPE file (Simple Features

v.clean applied:

Overlayed polygons topologically cleaned. Note the double categories.

See also