[RouterGeocoder] building different layer for routing.

[Stephen Woodbridge]

As a follow up on my previous post and to address a different aspect of 
layer. Many routing engines take a layered approach to routing, in that 
they break the routing into three stages.

Stage 1: search from the start point using Dijkstra algorithm with some 
kind of distance cut-off looking for access to a major route network.
Stage 2: reverse search from the end point using Dijkstra algorithm with 
some kind of distance cut-off looking for access from a major road network.
Stage 3: Check if there is a common node between Stage 1 and Stage 2, if 
so then declare victory. Otherwise, do an A* search from best node in 
Stage 1 to best node in Stage 2.

If road class (at least major vs minor) is maintained for arcs in the 
graph, then the router can choose to follow any or just major roads 
depending on the state it is in.

Best regards,
   -Steve

Ashraf Hossain wrote:
> Hi Steve,
> I must want to work with Nestor if I  have the opportunity.
> I have also a research group with one of my close friend.
> We both are interested and we will be honoured if we can contribute.
> 
> We already started our study about the performance for huge number of vertices.
> I think soon we can send some updates in this group, though we do not
> have huge big layer like USA and CANADA.
> If you have some suggestion about this please let me know.
> And another issue I have to know that if any operator updated their
> graph with USA and CANADA but if he want to add mexico(as a different
> layer) what should be our plan.
> Because if we make it as different graph then we have to start our
> plan in different way.
> 
> 
> And another one research about hybrid routing which is being used in
> google transit.
> If a user want to minimize bus route + taxi + walking in a single
> routing path generation,
> I already started thinking about this but the main problem is that how
> can we have the data?
> 
> If anyone have some suggestions please let me know.
> 
> With Regards
> Roni
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