[GRASS-dev] [GRASS GIS] #1595: v.clean break apparently does not work

GRASS GIS trac at osgeo.org
Sun Dec 2 10:54:16 PST 2012


#1595: v.clean break apparently does not work
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 Reporter:  pcav    |       Owner:  grass-dev@…              
     Type:  defect  |      Status:  new                      
 Priority:  normal  |   Milestone:  6.4.3                    
Component:  Vector  |     Version:  6.4.1                    
 Keywords:          |    Platform:  Linux                    
      Cpu:  x86-64  |  
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Comment(by mmetz):

 Replying to [ticket:1595 pcav]:
 > v.clean input=patched at paolo type=line tool=snap,break,rmdupl,rmsa
 > thresh=1,0,0,0 output=patched_1
 >
 > The lines are not broken.

 The vector 'patched' is the result of patching a 2D vector (region) with a
 3D vector (contour). The lines are not broken because there are no
 intersections in 3D space, only in 2D space. You need to transform the z
 coordinates of either the contour vector or the patched vector to be all
 zero with v.transform zscale=0, then the lines are broken.

 About the other problem described in the thread in comment [comment:2],
 how to snap bad polygons to good polygons, this is now possible with
 v.overlay, using the good polygons as ainput and the bad polygons as
 binput with operator=or. The snapping threshold may need to be set to some
 larger value than default=1e-8.

 Markus M

-- 
Ticket URL: <https://trac.osgeo.org/grass/ticket/1595#comment:3>
GRASS GIS <http://grass.osgeo.org>



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