[GRASS-user] v.net.path algorithm problem

[Markus Neteler]

On Wed, Mar 24, 2010 at 8:45 AM, schorschli <matthiasoswald at hotmail.com> wrote:
>
> Hi,
>
> I'm using v.net.path in a simple example:
>
> http://n2.nabble.com/file/n4789540/Network.png
>
> In my example I calculate the shortest path from all green dots (101, 102,
> 103) to all grey squares (1, 2, 3,...).The nodes are piped in with a
> textfile:
>
> 1 101 1
> 2 101 2
> 3 101 3
> 4 101 4
> 5 101 5
> 6 101 6
> 7 101 7
> 8 101 8
> 9 101 9
> 10 101 10
> 11 101 11
> 12 102 1
> 13 102 2
> 14 102 3
> 15 102 4
> 16 102 5
> ...
>
> It seems to me, that the algorithm has some problems. It can not find a path
> for all combinations. I get the following warning:
>
>
> WARNING: Point with category [7] is not reachable from point with category
>         [102]
> WARNING: Point with category [8] is not reachable from point with category
>         [102]
> WARNING: Point with category [9] is not reachable from point with category
>         [102]
> WARNING: Point with category [10] is not reachable from point with category
>         [102]
> WARNING: Point with category [11] is not reachable from point with category
>         [102]
> WARNING: 5 destination(s) unreachable (including points out of threshold)

Perhaps some nodes are missing? I have success in the past by applying
http://grass.osgeo.org/grass64/manuals/html64_user/v.net.html

to the map.

Markus