[GRASS-user] problem with v.edit tool=merge

Martin Landa landa.martin at gmail.com
Thu Mar 29 07:28:26 EDT 2007


Hi,

2007/3/29, Jarek Jasiewicz <jarekj at amu.edu.pl>:
> Martin Landa napisał(a):
> > Hi,
> >
> > no, there is another problem. Merge tool has been updated and snap
> > tool not. Snap tool in v.edit is very simple:
> >
> > 1) select lines
> > 2) snap *first two* lines from the list [regardless of threshold -- it
> > is a bug]
> >
> > see [1,2]
> >
> > Behaviour of merge tool is a little bit different. It tries to merge
> > *all* selected lines.
> >
> > So there is *important* question for future development of v.edit,
> > should be snap tool updated (snap all selected lines) or merge tool
> > modified according to current simplified snap tool (i.e. merge only
> > first two selected lines and  leave rest of selected lines untouched)?

> I rather suggest simplified form (eg.only two lines at once) because
> there be the problem with which line merge with which first and the
> second. In simple situation like this ---- ------    ------- it seems
> very simple but with that:
>
>
> --------
>              -----------
> -----------
>
> how to solve the proper order (cat, ids??) so results may be unpredictable

If I understand well you mean (??), e.g.

+
 \
   1
     \
      +-----2------
     /
    3
   /
+

If you select all three lines, they will be not merged, but if you
select only two lines (e.g. 1,2), they can be merged (it will cause
broken topology, this can be useful for example during networking (two
different roads, to eliminate joint node (cross-road))

v.edit map tool=merge id=1,2

+
  \
    1,2
      \
       +-----1,2----+
      /
     3
   /
+

Martin




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