[postgis-users] breake lines

[Andrea Peri]

St_node could work with a collection.
I guess the collection could have the two geometries.
A.

Il mar 3 set 2019, 19:36 Martin Davis <mtnclimb at gmail.com> ha scritto:

> If I'm understanding the requirement correctly, the problem with ST_Node
> is that it accepts a single geometry and nodes all lines in that geometry.
>
> It sounds like what's required is an ST_Node variant which would accept
> two arguments: a target geometry and a noding geometry.  The target
> geometry would be noded against the noding geometry, and then returned
> without incorporating any additional linework from the noding geometry.
>
> On Tue, Sep 3, 2019 at 10:22 AM Andrea Peri <aperi2007 at gmail.com> wrote:
>
>> Hi,
>> I will a chance trying to use the ST_Node.
>>
>> A.
>>
>>
>>
>>
>> Il mar 3 set 2019, 19:18 Martin Davis <mtnclimb at gmail.com> ha scritto:
>>
>>> Have you tried using ST_Split passing each input line and for the second
>>> argument a MultiLineString comprised of all lines that it might intersect
>>> (obtained via BBOX or ST_Intersects query)?  It seems like that should not
>>> create any duplicate linework from the input line.
>>>
>>> As far as I know there's no other way to do this using current PostGIS
>>> functions.   It's an interesting requirement - it sounds like essentially
>>> you want to node one layer against another.  There's actually the machinery
>>> to do this internally in PostGIS/GEOS, but it's never come up as a
>>> requirement before, so has not been exposed as a function.
>>>
>>> What is your use case?
>>>
>>> On Tue, Sep 3, 2019 at 9:48 AM <paul.malm at lfv.se> wrote:
>>>
>>>> If I split lines with another line layer, I will get a lot of
>>>> duplicaded line segments since the lines could be intersected several
>>>> times. It is not possible to use update on the table when splitting one
>>>> geomety to two.
>>>> I think it must be possible, but I’m not that skilled in SQL and I’ve
>>>> not found any examples on the net.
>>>>
>>>>
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>>
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