[postgis-users] breake lines

[paul.malm at lfv.se]

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.
Kind regards,
Paul

2 sep. 2019 kl. 07:41 skrev Malm, Paul (Operations AIM) <paul.malm at lfv.se<mailto:paul.malm at lfv.se>>:

Thanks, Simon!

Från: postgis-users [mailto:postgis-users-bounces at lists.osgeo.org] För Simon Norris
Skickat: den 30 augusti 2019 18:14
Till: PostGIS Users Discussion
Ämne: Re: [postgis-users] breake lines

You probably want ST_Split().
If you are working with your previous example, one way to avoid precision problems after applying the split might be to use the linear referencing funtions to shrink the lines by your preferred tolerance.

In case you haven't already seen it, this illustrates the numerical precision difficulty:
https://observablehq.com/@mourner/non-robust-arithmetic-as-art



On Aug 30, 2019, at 1:51 AM, paul.malm at lfv.se<mailto:paul.malm at lfv.se> wrote:

Hi,
What PostGIS command do I use to  breake linestrings or multilinestrings using  another “breaking” table including linestrings or multilinestrings, without erasing any points or adding anything from the “braking” layer?
Thanks in advance,
Paul
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