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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Hi,
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">If I understand your question correct, yes I would like to break all lines in the intersections with another layer.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">No I have not tried MultiLinestrings comprised of all lines that are intersecting the lines to be broken. Don’t know how to do this.
</span><span lang="EN-US" style="font-size:11.0pt;font-family:Wingdings;color:#1F497D">L</span><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">This is how far I have come:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">CREATE TABLE splittedlayer3
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">AS SELECT ST_CollectionExtract(ST_Split(o.the_geom, c.the_geom),2) as the_geom
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">FROM "orgLayer" o, "cutLayer" c WHERE ST_Intersects(o.the_geom, c.the_geom)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">But this gives duplicate line segments when intersecting the cutting lines twice.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">/Paul<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">Från:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> postgis-users [mailto:postgis-users-bounces@lists.osgeo.org]
<b>För </b>Martin Davis<br>
<b>Skickat:</b> den 3 september 2019 19:18<br>
<b>Till:</b> PostGIS Users Discussion<br>
<b>Ämne:</b> Re: [postgis-users] breake lines<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">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.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">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. <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">What is your use case?<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Tue, Sep 3, 2019 at 9:48 AM <<a href="mailto:paul.malm@lfv.se">paul.malm@lfv.se</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">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.<br>
I think it must be possible, but I’m not that skilled in SQL and I’ve not found any examples on the net.<br>
<br>
<o:p></o:p></p>
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