[GRASS-user] Re: [GRASSLIST:1098] v.net.steiner

[M S]

more questions on v.net.steiner.  i think i'm getting closer.

through QGIS i was able to detrmine that:
layer 0 (arc) = the lines connecting the buildings to the streets
layer 1 (arc) = the street network
layer 1 (point) = the buildings.

then i run:
v.net.steiner input=network output=network_steiner alayer=1 nlayer=1
tcats=1-208

then i get this output:
Number of Terminals: 207    <--- Should that be 208?
Number of Steiner points set to 205  <--- is that correct, given 1-208?
Killed
GrassPrompt->

any suggestions?  do all the arcs (the street connectors and the streets)
have to be on one layer? if so how do you do this?



On 6/15/06, M S <mseibel at gmail.com> wrote:
>
> seems like the terminals are identified by a layer number and range of
> categories.
>
> how do you get the layers associated with each feature type like arc,
> node, point? to input into the function?
>
> are the categories created while numbering basic elements first, and then
> complex ones?  meaning if you have two nodes and an arc, would the category
> number for the arc be 3?
>
>
>
> On 6/14/06, Markus Neteler <neteler at itc.it> wrote:
> >
> > On Wed, Jun 14, 2006 at 08:52:37AM -0400, M S wrote:
> > > nice document!  this is great stuff.
> >
> > Thanks. And note that data elaboration with the current
> > 6.1-CVS is even easier...
> >
> > > The v.net.steiner seems to be a realistic functional model by using an
> >
> > > existing (road) network to know what physical routes it can follow to
> > the
> > > given terminals.  this looks fantastic, and i cant wait to build some
> > test
> > > data.
> >
> > There should be a roads_net in spearfish6.0 which was recently
> > updated by Radim.
> >
> > > is there a function (raster or vector) that would allow for building
> > the
> > > network links/lines by inputting only the points without regards to an
> > > existing (road) network?  (using something like the minimum spanning
> > tree
> > > example below).  This function would be great as a first cut in
> > network
> > > analysis.
> >
> > You could use v.hull and then v.type to make it lines or use
> > v.extract to only extract the boundaries, then v.type for
> > boundaries -> lines. (untested)
> >
> > > the page below illustrates the minimum spanning tree, but if i
> > understand
> > > right, just nodes are inputted.  then the algorithm does at a minimum
> > 3
> > > things 1) identifies clusters of sites 2) builds the links to connect
> > the
> > > clusters to each other, and 3) then finds from each cluster, the
> > nearest
> > > point to other clusters.
> > > http://www.cs.sunysb.edu/~algorith/files/minimum-spanning-tree.shtml
> > <http://www.cs.sunysb.edu/%7Ealgorith/files/minimum-spanning-tree.shtml>
> > <http://www.cs.sunysb.edu/%7Ealgorith/files/minimum-spanning-tree.shtml>
> > >
> > > i dont think the v.net.steiner function does what the steiner-tree
> > function
> > > below illustrates, because the GRASS version uses an existing (road)
> > network
> > > to realistically model the existing pathways (nice implementation!).
> >
> > Kudos to Roberto Micarelli and Radim.
> >
> > >  This was the steiner tree example from the same site.
> > > http://www.cs.sunysb.edu/~algorith/files/steiner-tree.shtml<http://www.cs.sunysb.edu/%7Ealgorith/files/steiner-tree.shtml>
> > > I'm working with a Network Engineer on using GRASS to solve the
> > network
> > > analysis problems.  Using the NON-GRASS steiner tree (from example
> > above)
> > > wont work becuase as it goes to build the links, but connects lines to
> > > lines, rather than given nodes.  in the network implementaion this
> > would be
> > > a mid-span junction, or splicing the fiber at this junction to connect
> > the
> > > lines.  the minimum spanning tree is more applicable.  However, i
> > suspect
> > > that the GRASS minimum steiner tree is the most applicable and
> > realistic
> > > model/function.
> >
> > It would be great to have some examples online, for
> > http://grass.itc.it/applications/index.php
> >
> > > The GRASS minimum steiner tree is a realistic functional model that
> > uses
> > > real network data in conjunction with the terminals.  this seems like
> > a
> > > great deployment of the steiner tree in conjunction with consideration
> > to
> > > the existing network such as roads.  I cant wait to have some fun with
> > GRASS
> > > and give this a whirl!
> > >
> > > as usual, keep up the great work, and thanks to everyone who makes
> > GRASS GIS
> > > be all it can be!  feels great to find a GIS like this one which is
> > fun to
> > > work with, and has such community invovlement.  truely a great
> > environmant
> > > that makes GIS fun (again for me).
> >
> > Welcome!
> >
> > Markus
> >
> > >
> > > On 6/14/06, Markus Neteler <neteler at itc.it> wrote:
> > > >
> > > >M S wrote on 06/14/2006 03:13 AM:
> > > >
> > > >> The input parameter seems to be terminals.  Can they be points?
> > > >
> > > >They can be points (nodes) which have to be connected to the network.
> > > >You may take a look at:
> > > >http://mpa.itc.it/corso_dit2004/grass04_4_vector_network_neteler.pdf
> > > >slide 19
> > > >
> > > >Markus
> > > >
> > > >_______________________________________________
> > > >grassuser mailing list
> > > >grassuser at grass.itc.it
> > > > http://grass.itc.it/mailman/listinfo/grassuser
> > > >
> >
> > --
> > Markus Neteler     <neteler itc it>       http://mpa.itc.it
> > ITC-irst -  Centro per la Ricerca Scientifica e Tecnologica
> > MPBA - Predictive Models for Biol. & Environ. Data Analysis
> > Via Sommarive, 18        -       38050 Povo (Trento), Italy
> >
> > _______________________________________________
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> >
>
>
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