[GRASS-dev] [GRASS GIS] #3030: v. generalize fails to generalize polygons in a random manner

GRASS GIS trac at osgeo.org
Tue May 10 23:39:07 PDT 2016

#3030: v. generalize fails to generalize polygons in a random manner
  Reporter:  dido    |      Owner:  grass-dev@…
      Type:  defect  |     Status:  new
  Priority:  major   |  Milestone:  7.0.5
 Component:  Vector  |    Version:  7.0.4
Resolution:          |   Keywords:  v.generalize
       CPU:  x86-64  |   Platform:  MSWindows 7

Comment (by mmetz):

 Replying to [comment:2 dido]:
 > Added attachments with generalized data over the original data, where
 the non-generalized polygons are well-visible.

 Area boundaries are not generalized if the modification would damage
 topology or if the boundaries would be over-generalized (zero-length
 boundaries). In your output, you see

 Generalization (douglas)...
 Using threshold: 120 meters
 WARNING: 1953 boundaries were not modified because modification would
 damage topology
 WARNING: 1951 lines/boundaries were not modified due to over-

 That means the not generalized boundaries are not random, instead their
 generalization would cause errors, they should not be generalized and they
 are copied unmodified to the output. Try a smaller threshold or stepwise
 increase the threshold using the output of the previous simplification as
 input for the next simplification.

Ticket URL: <https://trac.osgeo.org/grass/ticket/3030#comment:7>
GRASS GIS <https://grass.osgeo.org>

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