[pgrouting-users] implement directions

[Pedro Costa]

Thank you for helping me Stephen and Greg.

I'm searching a code example of doing that but i don't find yet...
Do you know something? In wiki pages i don't find...
I'm working with my own data (pedestrian mode)  but if someone point me 
examples with other type (such osm) would be great to start


Thanks







Em 30-07-2012 19:09, Stephen Woodbridge escreveu:
> On 7/30/2012 1:24 PM, Greg Allensworth wrote:
>> On 7/30/2012 9:57 AM, Pedro Costa wrote:
>>> Em 30-07-2012 17:54, Pedro Costa escreveu:
>>>> Hi guys,
>>>> Can someone point to me some links or information about implement
>>>> driving directions in a pgrouting project?
>>> With driving directions i mean information about the select route like
>>> "turn right" ...
>>
>> http://postgis.refractions.net/pipermail/postgis-users/2007-November/017768.html 
>>
>>
>>
>> That's what I was going to use as a start, when I get to that phase of
>> our routing system. The "left" or "right" would be the difference
>> between the two lines' azimuth: if the difference is positive, and more
>> than 0.15 radians then it's a slight right, more than .50 radians it's a
>> sharp right, if the difference is negative then it's a left, if the
>> difference is <0.15 radians in either direction then it's not even a
>> turn that I care to mention, ....
>>
>> But I'm sure someone has developed and documented more of the math here,
>> beyond these first steps. I'm sure I'll be asking a few questions along
>> these lines, in a few weeks when I get to that phase.
>>
>
> Hi Guys,
>
> I have written a lot about this and implemented it for various 
> projects. Here is a google search that should find most of what I have 
> written:
>
> https://www.google.com/search?q=woodbridge+pgrouting+driving+directions
>
> Start by reading some of these and if you have questions I am willing 
> to help. The big issue with writing a "generic" solution is that it 
> really needs to be customized around the data you are using. The 
> pgrouting part gives you a list of edges, the driving directions 
> starts with this list of edges and then has to analyze things like are 
> the names the same on adjacent edges so you can compress the edges 
> into a single maneuver, when you get to an intersection, do the 
> analysis that Greg mentions to explicate the instruction, etc.
>
> If you want to see an integrated example of it look at:
>
> http://gis.imaptools.com/routing/leaddog/?zoom=11&lat=33.86651&lon=35.51184&layers=B0TTTF&start=35.493583%2033.826664&stop=35.565174%2033.864285&method=STS&lang=eng 
>
>
> You might think about this as a family of functions like
>
> -- basic pgrouting query, returns edge ids
> select * from shortest_path(...);
>
> -- convert route edge ids into maneuvers
> select * from maneuvers(shortest_path(...));
>
> -- convert maneuvers into textual directions
> select * from explicate(maneuvers(shortest_path(...)));
>
> The maneuvers are generic definition of an instruction. The 
> explication can then be a table driven instruction generation based on 
> a fixed set of maneuvers. If you want to have multi language support 
> like my example above, you just change the table from English template 
> to say French, German, Arabic, etc.
>
> Hope this helps,
>   -Steve
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