On Fri, Jan 14, 2011 at 1:21 PM, Daniel Kastl <daniel@georepublic.de> wrote:

Sorry, I was wrong … it’s the right function you’re using. Somehow read driving directions somewhere before.

Driving directions does what you need, except that it returns you a list of vertices you can reach and the edges column doesn’t return anything useful.This custom wrapper function takes the vertices and calculates a polygon that contains all of them:

https://github.com/pgRouting/pgrouting/blob/master/extra/driving_distance/sql/routing_dd_wrappers.sql#L78Yes this creates a polygon consisting all vertices but I want to display a road network that show how to go from source to outlying vertices. Actually I think driving distance’s edge info should give that info since it calculates a distance from source. If that function know how distant is the vertice it should know the path am I wrong on this ?

As I wrote, calculating shortest path for each vertex from source does not seem feasible. Can we make driving distance to show edge info ? I am willing to conribute in that sense but I don’t want to redo what is done before.

Driving Distance function uses Dijkstra algorithm:

https://github.com/pgRouting/pgrouting/blob/master/extra/driving_distance/src/drivedist.c#L341

Dijkstra only goes from vertex to vertex.

I know that dijkstra works from vertex to vertex but the shortest path implementation of dijksta in pgRouting is giving edge id’s as an output that it passed.

Now I found a solution to this problem by marking edges who has source or target vertex ids that is listed in driving distance query’s vertex list. But this takes 25 seconds to calculate. With a given edge id.

Is there any indexing or configuration to postgre that can speed up driving distance calculation ? or is there a more noble solution to this edge selection problem ?

Emre

@Anton: do you have some hint?

Daniel

–

Georepublic UG & Georepublic Japan

eMail: daniel.kastl@georepublic.de

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