[GRASS-user] Snap across layers

[Martin Landa]

Hi,

2008/1/28, Luca Casagrande <luca.casagrande at gmail.com>:
> Markus Neteler ha scritto:
> > - v.edit does it:
> >       bgmap   Name of background vector map(s) snap to
> > - the new digitizer in wxgrass does it (not yet enabled by default)

Luca:
> Before moving to my data, I am doing some tests with 2 vector layers:
>
> http://img337.imageshack.us/my.php?image=schermatamapdisplay1vp5.png
>
> Basically the small one, should snap to the bigger one.
> The command line I use is this:
>
> v.edit map=origine bgmap=destinazione cat=1-999 tool=snap thresh=-1
>
> But nothing change.
>
> In the log I have got a lot of line like this, both if i set thresh -1
> or 500
> [..]
> D1/1: Vect_set_thresh(): thresh = 0.000000
> [..]
>

tool 'snap' in v.edit uses library fn Vect_snap_lines() which doesn't
support snapping to the vector features from background map layer.

Snapping mode (no, node, vertex) and background map option works
currently only for tool='add'. For now, try to create an empty vector
map, export to ascii format the map you want to modify and update the
empty map, e.g.

v.edit a3 tool=create
v.out.ascii a2 format=standard | v.edit a3 tool=add bgmap=a1 id=1-999
thre=500 snap=node

Martin

-- 
Martin Landa <landa.martin at gmail.com> * http://gama.fsv.cvut.cz/~landa *