Many Thanks Steve, much clearer,
The Google Summer of code solutions, do they work ?
I am trying to work out how to use the Driving Distance version, the one
documented at http://www.pgrouting.org/docs/1.x/dd.html
I am confused as to what the distance function should be set up, but the page
http://underdark.wordpress.com/2011/05/13/catchment-areas-with-pgrouting-driving_distance/
Is very helpful which describes this value as
'the only new value is “distance”. That’s the maximum distance/cost you
want to be contained in the result set. “distance” has to be specified in
the same units as the cost attribute (which is specified in the “sql” text
parameter).'
Dave.
Stephen Woodbridge wrote:
On 1/30/2012 5:26 PM, Dave Potts wrote:
Is there a generic introduction which list what each of the route method
does and why I would what to use it with a given data set/There is a tutorial
http://www.pgrouting.org/docs/foss4g2008/index.html
and here is my assessment:Dijkstra solution:
This is a node based solution that converts a graph into a tree and the
tree has all nodes that are reachable from the start node. This is used
in the driving distance solution and has other applications where you
might want the cost to get to multiple node. The default output is to
only return that path from the start node to the destination node.Astar search solution:
This is a modified Dijkstra solver that uses a Heuristic to direct the
solver to the destination node. As a result, the graph solution is
typically faster the Dijkstra because you only have to solve part of the
graph needed to find the solution.ShootingStar solution:
This is an edge based solver. IT IS CURRENT BROKEN! and as best as I can
tell the last version that worked is v1.03. It is current running
significantly (2-4x slower than the above two solutions). The reason it
was created was because it support turn restrictions.These are the main three solvers.
We just added a new branch TRSP (turn restricted shortest pat