[pgrouting-users] Optimize routing - use new sew-devel-2_0 functions

[Frédéric Bonifas]

I agree the the routes will be relatively short for pedestrian routing, but :
* if I understand correctly how Dijkstra works, the routing time will
mostly depend on the size of the graph, as the whole graph will be
visited before giving the shortest_route.
* the fastest it is, the more I like it :)
* I show to the user different possible routes (4) so the routing time
is multiplied by this factor.

2013/5/22 Tao Romera Martinez <taoromera at gmail.com>:
> Hi Frederic,
>
> I once developped something similar to what you're doing, but since the use is for pedestrian routes, do you really need to generate routes longer than 30 or 40 km? Within this range, our very modest server works out routes in 1 second or so.
>
> I would be interested in knowing how to tackle your problem, though.
>
>
>
> 2013/05/22 18:25、Frédéric Bonifas <fredericbonifas at gmail.com> のメッセージ:
>
>> Hello,
>>
>> I have begun using PgRouting 3 months ago for pedestrian routing. So I
>> don't use reverse_cost nor tun restrictions.
>>
>> I have written my own wrapper in order to :
>> * set the start and end points as geographic points, the wrapper finds
>> the nearest edge, splits it in two parts and create a temporary vertex
>> (that will be used as start or stop vertex)
>> * compute the route with the "shortest_path" function
>> * output the route as a GeoJSON with additional information like the
>> total legnth of the route/
>>
>> It works fine for what I want but it is slow, especially on big
>> graphs. I guess this is partially because of the use of the Dijkstra
>> algorithm. I would like to improve that.
>>
>> With the recent developments around the sew-devel-2_0 branch, I would
>> like to use another routing algorithm. I am thinking of bidirectional
>> A*. To adapt my wrapper :
>> * would bidirectional A* be a good choice in my case ?
>> * is there a function in the sew-devel-2_0 branch to find the nearest
>> edge from a geographic point, split it in two parts and union this to
>> the graph for the routing ? I have looked here but I don't find this :
>> https://github.com/pgRouting/pgrouting/blob/sew-devel-2_0/src/common/sql/pgrouting_matching.sql
>> Otherwise, I will adapt my wrapper.
>> * is it good to output a GeoJSON in my wrapper as I do, or is there a
>> better way to go ?
>>
>> Thanks a lot for your ideas
>>
>> Best
>>
>> --
>> Frédéric Bonifas
>> +33672652807 skype:fredericbonifas
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--
Frédéric Bonifas
+33672652807 skype:fredericbonifas