[pgrouting-users] Splitting a network to create intersections

[Stephen Woodbridge]

Allen,

Jump on the postgis list archives, there has been a great exchange 
between Nicolas Ribot and myself on how to node a network of streets. 
The outcome is a very usable stored procedure, that will likely get 
included in pgrouting and has been posted on the list.

-Steve

On 5/7/2013 10:53 AM, Greg Allensworth wrote:
> Thanks a million. Steve, I'm not sure how I missed that link; it
> explains a lot. And dkastl, thank you too; that one small example of
> combining dump and split, clarifies some of the basic logic. Together
> these are a fine start.
>
> -G
>
>
> On 5/6/2013 8:50 PM, Stephen Woodbridge wrote:
>> On 5/6/2013 8:16 PM, Greg Allensworth wrote:
>>> A few weeks ago, Steve Mather posted, and one of his questions was about
>>> splitting up a trail network so as to create intersections, but without
>>> splitting unnecessarily.
>>>
>>> http://pgrouting-users.974093.n3.nabble.com/pgrouting-users-A-vs-Dijkstra-and-the-nature-of-the-A-implementation-td4025099.html
>>>
>>>
>>>
>>>
>>> The reply was basically "it's not that hard" which is good to hear,
>>> though I'm still trying to wrap my head around how exactly I would do
>>> this. Any explanation of the logic would be helpful there.
>>>
>>>
>>> This fellow at StackExchange posted some code, but but he says that it
>>> has problems that again I don't quite follow.
>>>
>>> http://gis.stackexchange.com/questions/34687/how-to-split-osm-roads-into-individual-segments-at-intersections
>>>
>>>
>>>
>>>
>>> Any comments on his approach, and what would be going wrong with it also
>>> creating the unsplit original segments?
>>>
>>>
>> Greg,
>>
>> I think you want to look at this thread:
>>
>> http://postgis.17.x6.nabble.com/Break-lines-at-intersections-td4663814.html
>>
>>
>> If you using postgis 1.5 then note 2nd & 3rd posts from the bottom.
>>
>> select st_astext(st_dump(st_union(the_geom)).geom) from lines;
>>
>> -Steve
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>
>