[GRASS-dev] Re: [GRASS GIS] #835: v.out.ogr -c flag doesn't work?

[GRASS GIS]

#835: v.out.ogr -c flag doesn't work?
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  Reporter:  lutra   |       Owner:  grass-dev at lists.osgeo.org
      Type:  defect  |      Status:  new                      
  Priority:  normal  |   Milestone:  6.4.0                    
 Component:  Vector  |     Version:  6.4.0 RCs                
Resolution:          |    Keywords:                           
  Platform:  Linux   |         Cpu:  x86-32                   
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Comment (by mmetz):

 The -c flag only has an effect if some features of the selected type have
 no category in the selected layer.

 That warning can be misleading because islands consist of one or more
 areas within a larger area. One island can consist of holes (areas that
 don't have a centroid with category) and valid areas (with centroid and
 category) at the same time, or only areas or only holes. If all areas in
 all islands have a centroid with category, the -c flag will indeed have no
 effect.

 Tested with landuse in the Spearfish dataset, exporting to shapefile once
 with once without -c flag. Holes are preserved with the -c flag, i.e.
 appear as holes (not filled areas) surrounded by filled areas. Without the
 -c flag, holes become valid areas that are displayed like any other area.
 Displaying both shapefiles in QGIS, the one with holes preserved on top of
 the other one with holes converted to areas, immediately shows the
 differences between the two vectors.

 Markus M

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Ticket URL: <http://trac.osgeo.org/grass/ticket/835#comment:1>
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