------------------------------
Message: 2
Date: Wed, 24 Mar 2010 15:34:28 +0100
From: Markus Neteler <[email protected]>
Subject: Re: [GRASS-user] v.net.path algorithm problem
To: schorschli <[email protected]>
Cc: GRASS user list <[email protected]>
Message-ID:
<[email protected]>
Content-Type: text/plain; charset=ISO-8859-1
On Wed, Mar 24, 2010 at 8:45 AM, schorschli <[email protected]> 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
Agreed, Markus. I get caught by this from time to time - it can drive me
nuts on a bad day.
Matthias - if you zoom very closely to any of the categories in the
error report, do you see a lack of connection between those points and
the network lines?
Richard Chirgwin
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