<html style="direction: ltr;">
<head>
<meta content="text/html; charset=windows-1255"
http-equiv="Content-Type">
<style type="text/css">body p { margin-bottom: 0cm; margin-top: 0pt; } </style>
</head>
<body style="direction: ltr;"
bidimailui-detected-decoding-type="preferred-charset"
bgcolor="#FFFFFF" text="#660000">
Here's an approach using Spatialite:<br>
You can use the spatialite functions DissolvePoints() or
DissolveSegments() to get each point or line segment along a
LINESTRING. Here's an example:<br>
<br>
(I created in advance a sample LINESTRING called 'seg')<br>
<tt>PRAGMA table_info("seg");</tt><br>
0 pk_uid integer 0 NULL 1<br>
1 label text 0 NULL 0<br>
2 Geometry LINESTRING 0 NULL 0<br>
<br>
<tt>SELECT * FROM seg;</tt><br>
1 a BLOB sz=176 GEOMETRY<br>
2 b BLOB sz=112 GEOMETRY<br>
<br>
(I have two simple LINESTRINGs)<br>
<tt>SELECT AsText(Geometry) FROM seg;</tt><br>
LINESTRING(1 1, 2 1, 2 2, 3 2, 4 2, 5 3, 6 2, 7 1)<br>
LINESTRING(2 2, 2 4, 4 4, 5 2)<br>
<br>
Now, I want to choose one of the linestrings, based on it's start
and end points:<br>
<tt>SELECT AsText(Geometry) FROM seg <br>
WHERE StartPoint(Geometry) = GeomFromText('POINT(1 1)', 4326)
AND<br>
EndPoint(Geometry) = GeomFromText('POINT(7
1)', 4326);</tt><br>
LINESTRING(1 1, 2 1, 2 2, 3 2, 4 2, 5 3, 6 2, 7 1)<br>
<br>
and to break up the LINESTRING into its segments:<br>
<tt>SELECT AsText(DissolveSegments(Geometry)) FROM seg <br>
WHERE StartPoint(Geometry) = GeomFromText('POINT(1 1)', 4326)
AND<br>
EndPoint(Geometry) = GeomFromText('POINT(7 1)', 4326);</tt><br>
MULTILINESTRING((1 1, 2 1), (2 1, 2 2), (2 2, 3 2), (3 2, 4 2), (4
2, 5 3), (5 3, 6 2), (6 2, 7 1))<br>
<br>
<br>
Maybe that will help.<br>
<br>
On 24/06/2012 10:53, chathura silva wrote:
<blockquote
cite="mid:CAA+c9bsUgHe-rthjjcd54dwnKeCQmSG-zWinpCtjTQRsKGexHw@mail.gmail.com"
type="cite">
<div id=":14q" dir="ltr" class="kl">suppose you are given the
co-ordinates of starting and end points of a road segment.</div>
<div id=":14s" dir="ltr" class="kl">Is there any way to extract
the other set of co-ordinates laying on the road segment</div>
<div id=":153" dir="ltr" class="kl">?<br>
<br>
</div>
<br>
This mail was received via Mail-SeCure System.<br>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
<pre wrap="">_______________________________________________
Qgis-user mailing list
<a class="moz-txt-link-abbreviated" href="mailto:Qgis-user@lists.osgeo.org">Qgis-user@lists.osgeo.org</a>
<a class="moz-txt-link-freetext" href="http://lists.osgeo.org/mailman/listinfo/qgis-user">http://lists.osgeo.org/mailman/listinfo/qgis-user</a>
This mail was received via Mail-SeCure System.
</pre>
</blockquote>
<font size="+1"></font><br>
<br>
<pre class="moz-signature" cols="72">--
Micha Silver
052-3665918
</pre>
</body>
</html>