[GRASS-dev] [GRASS GIS] #2936: v.net.distance: wrong directions in one-way streets

[GRASS GIS]

#2936: v.net.distance: wrong directions in one-way streets
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  Reporter:  mlennert    |      Owner:  grass-dev@…
      Type:  defect      |     Status:  new
  Priority:  normal      |  Milestone:  7.0.4
 Component:  Vector      |    Version:  svn-trunk
Resolution:              |   Keywords:  v.net.distance network one-way
       CPU:              |  direction
  Unspecified            |   Platform:  Unspecified
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Comment (by mlennert):

 Replying to [comment:1 mmetz]:
 > Manual:
 >
 > "Each path consist of several lines. If a line is on the shortest path
 from a point then the category of this point is assigned to the line. Note
 that every line may contain more than one category value since a single
 line may be on the shortest path for more than one from feature."
 >
 > That means lines are copied directly from input to output, line
 directions are not adjusted and lines are not merged to unique paths for
 each `from` category.
 >
 > Unfortunately, the paths as reported by v.net.distance (irrespective of
 the direction) are wrong: the shortest path from 7779 to 7780 should take
 the long route, and the shortest path from 7780 to 7779 should take the
 short route. Fixing this bug would require a new function in
 lib/vector/neta. Hopefully the dglib interface allows for an easy solution
 to provide an inverse to
 lib/vector/neta/path.c:NetA_distance_from_points().
 >
 > This ticket should be closed and a new ticket should be opened that
 v.net.distance calculates paths in reverse (from to to from instead of
 from from to to).


 I don't understand why we need a new ticket. Maybe my formulation was a
 bit awkward, but the problem reported in the ticket is exactly that
 v.net.distance calculates paths in reverse...

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Ticket URL: <https://trac.osgeo.org/grass/ticket/2936#comment:2>
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