[Qgis-user] network building tool

[G. Allegri]

If your nodes have origin/destination attribute and a common id for
connecting nodes, I suppose you could use a VIEW, even if it would be
rather inefficient for big number of nodes.
It would work in Spatialite too.

giovanni


2013/11/21 Vincent Picavet <vincent.ml at oslandia.com>

> Hi,
>
> [...]
> > > > Then, a procedure would read the connections from the table and draw
> > > > automatically these connecting lines between the nodes.
> > >
> > > If you want straight lines between nodes, it is easy. Otherwise you
> would
> > > have > to state rules for making the lines between the nodes, and it
> can
> > > be  simple or very complicated to automate according to the rules.
> >
> > See my workflow in:
> > http://thread.gmane.org/gmane.comp.gis.qgis.user/24511/focus=24527
>
> If it is a matter of changing the last vertex of an already existing
> geometry,
> it is doable and quite easy, even if a bit more complicated than a simple
> makeline.
>
> > > Here is a PostGIS example of creating the edge geometry given to/from
> > > nodes : https://gist.github.com/vpicavet/7572293
> >
> > Do you think that this could be done as well with non-server based
> storage
> > (shapefile, sqlite/spatialite)?
> With spatialite you may be able to do the same thing, as sqlite has
> triggers
> too, but it is not as easy. You cannot create custom functions, so if your
> edge geometry creation is very complex it will probably be very tricky.
>
> > > This behaviour is transparent for a visualization client, QGIS for
> > > exemple.
> >
> > Great. give me some time to test on it.
> ok
>
> Vincent
>
> >
> > Thanks for your follow-up.
> >
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-- 
Giovanni Allegri
http://about.me/giovanniallegri
blog: http://blog.spaziogis.it
GEO+ geomatica in Italia http://bit.ly/GEOplus
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