<div dir="ltr">I tried saving a few layers that had arcs and circles (x,y, r coords), but QGIS converts each curve to a bunch of straight line segments instead of saving them as curves. :-(</div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Apr 22, 2019 at 3:33 AM McDonaldR <<a href="mailto:McDonaldR@angus.gov.uk">McDonaldR@angus.gov.uk</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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<p class="MsoNormal"><span style="font-size:11pt;font-family:"Century Gothic",sans-serif;color:rgb(31,73,125)">As your data is in PostGIS and assuming that they are arcs (curved lines part of a circle) you could use some geometry and
spatial SQL functions to calculate the radius of any curve knowing the coordinates of the end points of the curve.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:"Century Gothic",sans-serif;color:rgb(31,73,125)"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:"Century Gothic",sans-serif;color:rgb(31,73,125)">To quote the pseudo code on the linked page:<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:"Century Gothic",sans-serif;color:rgb(31,73,125)"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:"Century Gothic",sans-serif;color:rgb(31,73,125)">“</span><span style="font-family:Arial,sans-serif;color:black;background:rgb(251,251,251)">To calculate the radius of an arc, take
the height -- "H" -- of the arc and divide it by two. Call the result "C." Now take the width -- "W" -- of the arc and square it by multiplying it by itself. Call the result "D." Next multiply height, "H," by eight and call this result "E." Divide "D" by "E"
and call the result "F." The radius of the arc is C plus F.”</span><span style="font-size:11pt;font-family:"Century Gothic",sans-serif;color:rgb(31,73,125)"><u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:"Century Gothic",sans-serif;color:rgb(31,73,125)"><u></u> <u></u></span></p>
<p class="MsoNormal"><a href="https://sciencing.com/calculate-radius-curve-7804090.html" target="_blank">https://sciencing.com/calculate-radius-curve-7804090.html</a><span style="font-size:11pt;font-family:"Century Gothic",sans-serif;color:rgb(31,73,125)"><u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:"Century Gothic",sans-serif;color:rgb(31,73,125)"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:"Century Gothic",sans-serif;color:rgb(31,73,125)">Could probably be wrapped in a function and run against any curve.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:"Century Gothic",sans-serif;color:rgb(31,73,125)"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:"Century Gothic",sans-serif;color:rgb(31,73,125)">Ross<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11pt;font-family:"Century Gothic",sans-serif;color:rgb(31,73,125)"><u></u> <u></u></span></p>
<p class="MsoNormal"><b><span lang="EN-US" style="font-size:11pt;font-family:Calibri,sans-serif">From:</span></b><span lang="EN-US" style="font-size:11pt;font-family:Calibri,sans-serif"> Qgis-user [mailto:<a href="mailto:qgis-user-bounces@lists.osgeo.org" target="_blank">qgis-user-bounces@lists.osgeo.org</a>]
<b>On Behalf Of </b>Cory Albrecht<br>
<b>Sent:</b> 19 April 2019 17:08<br>
<b>To:</b> <a href="mailto:qgis-user@lists.osgeo.org" target="_blank">qgis-user@lists.osgeo.org</a><br>
<b>Subject:</b> Re: [Qgis-user] finding the radius of a curve<u></u><u></u></span></p>
<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">I'll give it a try. Thanks!<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">On Sun, Apr 14, 2019 at 7:52 AM Mike Flannigan <<a href="mailto:mikeflan@att.net" target="_blank">mikeflan@att.net</a>> wrote:<u></u><u></u></p>
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Draw a circle and measure the diameter/radius.<br>
<br>
Maybe use this plugin to create a circle:<br>
<a href="https://plugins.qgis.org/plugins/CADDigitize/" target="_blank">https://plugins.qgis.org/plugins/CADDigitize/</a><br>
<br>
<br>
Mike<br>
<br>
<br>
On 4/13/2019 2:00 PM, <a href="mailto:qgis-user-request@lists.osgeo.org" target="_blank">
qgis-user-request@lists.osgeo.org</a> wrote:<br>
> Hello all,<br>
><br>
> I'm looking for a way to find the radius of a curve (for roads, railyways)<br>
> in QGIS. If it were a paper map I could do it with a drafting compass<br>
> (calipers to some) and a ruler, but this is a PostGIS layer.<br>
><br>
> Any plugin recommendations or links to a set of steps to accomplish this?<br>
> Thanks in advance!<u></u><u></u></p>
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