<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<meta name="Generator" content="Microsoft Word 14 (filtered medium)">
<!--[if !mso]><style>v\:* {behavior:url(#default#VML);}
o\:* {behavior:url(#default#VML);}
w\:* {behavior:url(#default#VML);}
.shape {behavior:url(#default#VML);}
</style><![endif]--><style><!--
/* Font Definitions */
@font-face
{font-family:Wingdings;
panose-1:5 0 0 0 0 0 0 0 0 0;}
@font-face
{font-family:Wingdings;
panose-1:5 0 0 0 0 0 0 0 0 0;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0cm;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman","serif";}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
p
{mso-style-priority:99;
margin:0cm;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman","serif";}
p.xmsonormal, li.xmsonormal, div.xmsonormal
{mso-style-name:x_msonormal;
margin:0cm;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman","serif";}
span.E-postmall19
{mso-style-type:personal-reply;
font-family:"Calibri","sans-serif";
color:#1F497D;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page WordSection1
{size:612.0pt 792.0pt;
margin:70.85pt 70.85pt 70.85pt 70.85pt;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang="SV" link="blue" vlink="purple">
<div class="WordSection1">
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Thanks Lars, I will have this in mind, but for now I would like to learn SQL and will take a look at Topology later on.<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">Kind regards,<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>
<div>
<div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm">
<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>Lars Aksel Opsahl<br>
<b>Skickat:</b> den 6 september 2019 14:31<br>
<b>Till:</b> postgis-users@lists.osgeo.org<br>
<b>Ämne:</b> Re: [postgis-users] breake lines<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black">Hi<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black"><o:p> </o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black">Another option to handle merging off different simple feature datasets into a single dataset can be Postgis Topology.<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black"><o:p> </o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black">What we basically do is that we pipe the datasets into Postgis Topology which solves the problems related to breaking up lines and snap to.<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black"><o:p> </o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black">Then we take the data out as simple Feature from Postgis Topology and the users can continue to work on a nice a clean simple feature dataset. <o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black"><o:p> </o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black">We have done this for datasets containing millions of points and it works quite nice..</span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black"><o:p> </o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black">Lars <o:p></o:p></span></p>
</div>
<div>
<div>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:black"><o:p> </o:p></span></p>
</div>
<div class="MsoNormal" align="center" style="text-align:center">
<hr size="2" width="98%" align="center">
</div>
<div id="divRplyFwdMsg">
<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:black"> postgis-users <postgis-users-bounces@lists.osgeo.org> on behalf
of paul.malm@lfv.se <paul.malm@lfv.se><br>
<b>Sent:</b> Wednesday, September 4, 2019 1:53 PM<br>
<b>To:</b> postgis-users@lists.osgeo.org <postgis-users@lists.osgeo.org><br>
<b>Subject:</b> Re: [postgis-users] breake lines</span> <o:p></o:p></p>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
</div>
<div>
<div>
<p class="xmsonormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Hi,
</span><o:p></o:p></p>
<p class="xmsonormal"><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.</span><o:p></o:p></p>
<p class="xmsonormal"><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><o:p></o:p></p>
<p class="xmsonormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
<p class="xmsonormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">This is how far I have come:</span><o:p></o:p></p>
<p class="xmsonormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
<p class="xmsonormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">CREATE TABLE splittedlayer3
</span><o:p></o:p></p>
<p class="xmsonormal"><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
</span><o:p></o:p></p>
<p class="xmsonormal"><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)</span><o:p></o:p></p>
<p class="xmsonormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> </span><o:p></o:p></p>
<p class="xmsonormal"><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.</span><o:p></o:p></p>
<p class="xmsonormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">/Paul</span><o:p></o:p></p>
<p class="xmsonormal"><span lang="EN-US"> </span><o:p></o:p></p>
<p class="xmsonormal"><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</span><o:p></o:p></p>
<p class="xmsonormal"> <o:p></o:p></p>
<div>
<div>
<p class="xmsonormal">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>
</div>
<div>
<p class="xmsonormal"> <o:p></o:p></p>
</div>
<div>
<p class="xmsonormal">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>
</div>
<div>
<p class="xmsonormal"> <o:p></o:p></p>
</div>
<div>
<p class="xmsonormal">What is your use case?<o:p></o:p></p>
</div>
<p class="xmsonormal"> <o:p></o:p></p>
<div>
<div>
<p class="xmsonormal">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>
</div>
<blockquote style="border:none;border-left:solid #CCCCCC 1.0pt;padding:0cm 0cm 0cm 6.0pt;margin-left:4.8pt;margin-top:5.0pt;margin-right:0cm;margin-bottom:5.0pt">
<p class="xmsonormal" 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.<o:p></o:p></p>
</blockquote>
</div>
</div>
</div>
</div>
</div>
</div>
</body>
</html>