[GRASS-dev] Re: [GRASS GIS] #829: v.in.ogr: when pointing to a folder import of vectors can produce wrong results

[GRASS GIS]

#829: v.in.ogr: when pointing to a folder import of vectors can produce wrong
results
----------------------+-----------------------------------------------------
  Reporter:  lutra    |       Owner:  grass-dev at lists.osgeo.org
      Type:  defect   |      Status:  closed                   
  Priority:  major    |   Milestone:  6.4.0                    
 Component:  Vector   |     Version:  6.4.0 RCs                
Resolution:  invalid  |    Keywords:  v.in.ogr                 
  Platform:  All      |         Cpu:  x86-32                   
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Changes (by mmetz):

  * status:  new => closed
  * resolution:  => invalid

Comment:

 The overlap area becomes a separate area because a topological vector
 format like in grass does not allow overlapping areas. You can try to
 preserve the original areas with

 {{{
 v.in.ogr -c
 }}}

 (don't apply topological cleaning to areas), but may need to manually
 place centroids of overlapping areas in a non-overlapping part of the
 area; this is supported in grass and will give you a vector without
 errors. Shapefiles are not topological, i.e. there is no connection
 whatsoever between two polygons, be they separate, adjacent or
 overlapping. Some other (proprietary) GIS applications with native
 topological vectors don't even allow partially overlapping areas like
 grass does.

 In short, the results you got are the expected ones and the ticket is
 invalid, but I hope I could clarify nevertheless why grass behaves the way
 it does. Some more info is in the vector intro part of the manual.

 Markus M

-- 
Ticket URL: <http://trac.osgeo.org/grass/ticket/829#comment:1>
GRASS GIS <http://grass.osgeo.org>