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