Hi Markus, I was very surprised to read your comment about v.net.distance since the manual indicates the following:
> "v.net.distance - Computes shortest distance via the network between the > given sets of features. > Finds the shortest paths from each 'from' point to the nearest 'to' > feature and various information about this relation are uploaded to the > attribute table" > Is it possible that you had a mistake, or is it that the manual is incorrect? Is the manual *is* correct? How can I assign costs to the destination nodes to receive the "lowest cost" (shortest) path from each origin node to the nearest (cheapest) target node? Best, Dor 2013/3/29 Markus Metz <[email protected]> > On Thu, Mar 28, 2013 at 2:52 PM, דור פרידמן <[email protected]> wrote: > > Hello all, > > > > After I've got my v.net.distance up and running I have to adjust my > analysis > > method to the software's capabilities. Basically, I have a 3 layered > > network: myroads_net2 which contain layers as follow: > > > > Layer 1: Arch (roads) > > Layer 2: Points (Landfills - destinations) > > Layer 3: Points (Settlements - source) > > > > As one might understood I'm trying to calculate the lowest cost route > > between each settlement (layer 3) to each landfill (layer 2). > > I think v.net.distance is the wrong module for this task because it > finds for each 'from' feature the nearest 'to' feature and not the > shortest path from each 'from' feature to each 'to' feature. Actually, > I don't think any of the v.net.* modules does exactly that. You could > file a ticket for enhancement to request such a module. > > > Roads' costs > > are constant, which now set to 1 (currency per distance unit - I guess > that > > it is meter). I would like to include a cost for landfill (gate fee) > which > > will be measured with the same currency. MY attempt to use ncolumn (cost > for > > nodes) didn't go well. I have opened a new column (double precision) in > > layer 2 and named it gatefee. I have assigned 0 to all cats, except cat=3 > > which I have assigned with 60. My expectation was that at least some of > the > > settlements that were allocated to cat=3 on layer 2 will be allocated to > > another one. However after running v.net.distance again with > ncolumn=gatefee > > I have found out that more settlements were allocated to cat=3 of layer > 2. > > If I understand the code of v.net.distance correctly, node costs are > ignored. > > Markus M > > > > > Did I misused that option? I can't find any guide to how to use it in the > > manual or tutorials and will appreciate an explanation or a reference to > > such guide or tutorial. > > > > Best, > > > > Dor > > > > _______________________________________________ > > grass-user mailing list > > [email protected] > > http://lists.osgeo.org/mailman/listinfo/grass-user > > >
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