[pgrouting-users] Splitting a network to create intersections

[Greg Allensworth]

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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Greg Allensworth, Web GIS Developer
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