How to snap nodes

[Markus Neteler]

On Tue, Aug 22, 2000 at 12:13:47AM +0000, David D Gray wrote:
> GRASS wrote:
> > 
> > Hi all,
> > 
> > I imported some DXF's as follows:
> > 
> >         v.in.dxf dxf=a.dxf lines=7111,7114
> >         v.in.dxf3d dxf=a.dxf lines=7111,7114
> >         v.support map=a.7111 option=build
> >         v.support map=a.7114 option=build
> >         v.patch input=a.7111,a.7114 output=a
> > 
> >         v.in.dxf dxf=b.dxf lines=7111,7114
> >         v.in.dxf3d dxf=b.dxf lines=7111,7114
> >         v.support map=b.7111 option=build
> >         v.support map=b.7114 option=build
> >         v.patch input=b.7111,b.7114 output=b
> > 
> >         v.patch input=a,b output=ab
> >         v.support map=ab option=build -s threshold=1
> > 
> > This failed to snap nodes.
> > 
> >         d.vect ab
> > 
> > draws two disconnected maps.
> > 
> > What's wrong?
> > 
> > Regards,
> > Huidae Cho
> 
> 
> Hi
> 
> Some thoughts:-
> 
> Is the snap distance enough? If it's not that, maybe try changing the
> scale value in v.digit (to a small value like 200 or 50). At present
> nodes will only snap to other nodes, not for example to lines. Perhaps
> that is a thought for future development.
> 
> David
> 

ANother comment:
Please check if a map scale has been set to the map. If not, the
snapping won't work (I already got that experience).

Use v.digit to set the map scale to a reasonable value.
If there is none, the v.in.dxf should be modified to set either
the correct scale (if it can be found in DXF file) or a 
default map scale. A map scale of 1:1 will not work.

Maybe this helps?

 Markus

-- 
Dipl.-Geogr. Markus Neteler *  University of Hannover
Institute of Physical Geography and Landscape Ecology
Schneiderberg 50 * D-30167 Hannover * Germany
Tel: ++49-(0)511-762-4494  Fax: -3984