[GRASS-dev] Re: [GRASS GIS] #1470: v.out.ascii with sql where option exports only centroids and not areas

[GRASS GIS]

#1470: v.out.ascii with sql where option exports only centroids and not areas
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 Reporter:  marisn       |       Owner:  grass-dev@…              
     Type:  defect       |      Status:  new                      
 Priority:  normal       |   Milestone:  6.4.3                    
Component:  Vector       |     Version:  svn-trunk                
 Keywords:  v.out.ascii  |    Platform:  Unspecified              
      Cpu:  Unspecified  |  
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Comment(by mmetz):

 Replying to [comment:3 martinl]:
 > Replying to [comment:2 mlennert]:
 > > Replying to [ticket:1470 marisn]:
 > > This is logicial in the sens that only the centroid has a cat=5109. No
 boundary has this cat. So this would mean implementing a specific
 algorithm to check which boundary needs to be exported together with this
 centroid.
 >
 > Basically it could be possible. Currently `v.out.ascii` opens vector map
 on level 1 (without topology). This would require level 2 (topology). I
 can imagine special flag which writes out also areas (boundaries and
 centroids), not only centroids. The problem is that boundaries of adjacent
 areas will printed twice. I am not sure whether it's a good idea to extend
 functionality of this module in this direction. Any opinion?

 There is enough code in GRASS (other modules, libs) that takes care of
 such cases, boundaries would not be written twice. Basically a boundary
 would be written out if the centroid of any of its two areas has a cat
 value which is in the list. I would like to see that option/functionality
 in `v.out.ascii` because most of the time the vector objects a user works
 with are points, lines, areas. Modules/libs then take care of appropriate
 handling of boundaries and centroids.

 my2c

 Markus M

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Ticket URL: <http://trac.osgeo.org/grass/ticket/1470#comment:5>
GRASS GIS <http://grass.osgeo.org>