[GRASS-dev] [GRASS GIS] #2669: v.net.iso: different results depending on direction

[GRASS GIS]

#2669: v.net.iso: different results depending on direction
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 Reporter:  mlennert                          |      Owner:  grass-dev@…
     Type:  defect                            |     Status:  new
 Priority:  normal                            |  Milestone:  7.0.1
Component:  Vector                            |    Version:  svn-trunk
 Keywords:  network v.net.iso direction cost  |        CPU:  Unspecified
 Platform:  Unspecified                       |
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 Testing v.net.* modules to see whether the number of vertices in lines
 makes a difference for results (for info: it doesn't), I came upon a weird
 bug.

 I digitized three +/- parallel lines (with different number of vertices)
 and start points at more or less similar positions on these lines.

 Then:

 {{{

 v.net test_lines points=test_points op=connect thresh=500 out=network
 v.db.update network col=cost qcol="length/(speed*1000/60)"
 v.net.iso input=network at isochrones output=isos center_cats=1-3
 costs=5,10,15,20,25,30,35,40 arc_column=cost

 }}}

 So cost is the same in both directions. However, the result I get is very
 different depending on the direction from the starting point (cf attached
 image - numbers are the categories from v.net.iso, blue circles are the
 start points).

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Ticket URL: <https://trac.osgeo.org/grass/ticket/2669>
GRASS GIS <http://grass.osgeo.org>