[GRASSLIST:2866] Re: shortest path
blazek at itc.it
Mon Mar 8 03:34:24 EST 2004
On Sunday 07 March 2004 10:58, you wrote:
> Hello dear all,
> At first I want to say : "Thank you so much" with your
> help now I can do many things :)
> At this time I want to know more about network
> analysis in GRASS. Specifically about the algorithm
> that GRASS uses to find shortest path between points
> in 'v.net.path' module. I want to know if we don't
> determine the 'afcol', 'abcol' and 'ncol' costs, then
> what is measured for finding path?
Length of network segments and 0 for nodes.
> and when we specify
> these values how they influence in algorithm?
These values are taken as costs of whole segments, i.e.
the length of segments is not used. For example, if you have for each
line in the network attribute 'max_speed' and 'length', you can get
more precise results, if you are looking for fastest path, using
afcol=length/max_speed (pg driver)
> Is there any document that can help me in this way?
> Any suggestion will be so appreciated.
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