[GRASS-user] to separate a polygon

[Vincent Bain]

well,
depends on what accuracy you require, but an automated method could
however fit your needs :
v.to.rast -> r.thin -> r.to.vect -> v.clean

i.e :
turn your polygon into a raster map,
perform a thinning on the resulting map,
turn back this rasterized/thinned network into a vector map,
optionnally clean extra nodes with v.clean.

Hope this helps,
Good luck,

Vincent


Le mardi 09 février 2010 à 16:41 +0100, Yvan Paillé a écrit :
> Yes, that's it!
> Good well, I'll take my pain with patience and digitize point by point.
> 
> Thank you
> 
> yvan
> 
> 
> 
> 
> 
> 
> 
> Vincent Bain a écrit :
> > AFAIU :
> > * your network was digitized as a single polygon, contouring
> > streets/roads and crossroads in one go ;
> > * you would like to turn it into a linear reference network.
> > Am I right ?
> > If no special splitting was initially performed on boundaries to
> > distinguish between connected street sections I fear you'll have to do
> > things manually...
> > 
> > Vincent
> > 
> > 
> > Le mardi 09 février 2010 à 16:03 +0100, Yvan Paillé a écrit :
> >> My road network was digitized into a polygon. Initially, I need to 
> >> separate into two distinct parts by half. In a second time, I need to 
> >> cut each polygon based on the streets and of belonging to adjacent 
> >> parcels. As if I would define a sidewalk.
> >>
> >> Only the first step is already causing me problems.
> >>
> >> Thank you
> >>
> >> Yvan
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >> Vincent Bain a écrit :
> >>> Yvan,
> >>> could you please state your intention ? and clarify how your network is
> >>> represented : are roads delimited by polygon boundaries and crossroads
> >>> by nodes ? or was the network digitized as a polygon (I mean giving
> >>> roads thickness) ?
> >>>
> >>> First, about data type conversion, you can have a look at v.type.
> >>>
> >>> Yours,
> >>> Vincent.
> >>>
> >>>
> >>> Le mardi 09 février 2010 à 15:14 +0100, Yvan Paillé a écrit :
> >>>> Hello,
> >>>> I would like to separate a polygon that represents a road network into 
> >>>> several polygons or polylines. I do not know what functions to use to 
> >>>> display vertices and nodes.
> >>>> Thank you in advance for answers that guide me.
> >>>>
> >>>> Yvan
> >>>> _______________________________________________
> >>>> grass-user mailing list
> >>>> grass-user at lists.osgeo.org
> >>>> http://lists.osgeo.org/mailman/listinfo/grass-user
> >>>>
> >>
> 
>