Difference between revisions of "Vector topology cleaning"

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'''Q:''' How about self-intersecting lines and boundaries?
 
'''Q:''' How about self-intersecting lines and boundaries?
  
'''A:''' In the GRASS topological model self-intersecting lines are allowed, self-intersecting boundaries are not.
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'''A:''' In the GRASS topological model self-intersecting lines are allowed, self-intersecting boundaries are not. Self-intersecting lines are ok e.g. for {{cmd|v.net}} modules, e.g. to represent a bridge of a secondary road over a highway.
Self-intersecting lines are ok e.g. for {{cmd|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 {{cmd|v.buffer}} problems are expected.
 
Note: There are some modules that do not like self-intersecting lines, e.g with {{cmd|v.buffer}} problems are expected.
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=== See also ===
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* [[Vector topology]]
  
 
[[Category:FAQ]]
 
[[Category:FAQ]]
 
[[Category:Vector]]
 
[[Category:Vector]]

Revision as of 17:39, 6 December 2011

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.

See also