[postgis-users] routing and network analysis

[Justin Deoliveira]

Hi Robin,

I have built a network building/walking framework that is precisley for 
solving problems like the one you describe. It is part of the geotools 
project, in a module called "graph". See http://www.geotools.org/

The way it works is you pull all of the relevant geometries (in your 
case road linestrings) out of the database and build a graph. Then walk 
the graph to answer questions like give me the shortest path from node 1 
to node 2.

The main drawback is that the entire graph has to be stored in main 
memory. So if you are working with mass amounts of data then you might 
need something a bit more elegant.

Let me know if you are interested and I can send you some sample code.

Justin

Robin Chauhan wrote:
> I have a PostGIS database of geographic points which I would like to
> find shortest paths between.
> 
> a) I have access to road network data.  I've heard the new GRASS can
> be used to do network analysis.  anyone heard if it would be promising
> in combination with postGIS, or could suggest another package?
> 
> b) as an alternative, can anyone suggest or point to an efficient
> approach for computing the shortest path between two points which does
> not go through, say, water polygons?
> 
> thanks in advance,
> -Robin Chauhan
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-- 
Justin Deoliveira
Refractions Research Inc.
jdeolive at refractions.net
(250) 885-4387