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<p>Hi Cory,</p>
<p>Not if you use a file-format that supports arcs: Geopackage,
Postgis, Interlines, GML. Maybe also FGDB (but not sure if OGR
supports curves for that format).<br>
</p>
<p>Greetings,</p>
<p>Andreas<br>
</p>
<div class="moz-cite-prefix">Am 29.04.19 um 18:21 schrieb Cory
Albrecht:<br>
</div>
<blockquote type="cite"
cite="mid:CAMW5rYKpFbfEqJmTmPDNxrmQK5khGMdc_gqrJ9-gQDh3qoJc_Q@mail.gmail.com">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<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"
moz-do-not-send="true">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">
<div lang="EN-GB">
<div class="gmail-m_4032411246367673761WordSection1">
<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.</span></p>
<p class="MsoNormal"><span
style="font-size:11pt;font-family:"Century
Gothic",sans-serif;color:rgb(31,73,125)"> </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:</span></p>
<p class="MsoNormal"><span
style="font-size:11pt;font-family:"Century
Gothic",sans-serif;color:rgb(31,73,125)"> </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)"></span></p>
<p class="MsoNormal"><span
style="font-size:11pt;font-family:"Century
Gothic",sans-serif;color:rgb(31,73,125)"> </span></p>
<p class="MsoNormal"><a
href="https://sciencing.com/calculate-radius-curve-7804090.html"
target="_blank" moz-do-not-send="true">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)"></span></p>
<p class="MsoNormal"><span
style="font-size:11pt;font-family:"Century
Gothic",sans-serif;color:rgb(31,73,125)"> </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.</span></p>
<p class="MsoNormal"><span
style="font-size:11pt;font-family:"Century
Gothic",sans-serif;color:rgb(31,73,125)"> </span></p>
<p class="MsoNormal"><span
style="font-size:11pt;font-family:"Century
Gothic",sans-serif;color:rgb(31,73,125)">Ross</span></p>
<p class="MsoNormal"><span
style="font-size:11pt;font-family:"Century
Gothic",sans-serif;color:rgb(31,73,125)"> </span></p>
<p class="MsoNormal"><b><span
style="font-size:11pt;font-family:Calibri,sans-serif"
lang="EN-US">From:</span></b><span
style="font-size:11pt;font-family:Calibri,sans-serif"
lang="EN-US"> Qgis-user [mailto:<a
href="mailto:qgis-user-bounces@lists.osgeo.org"
target="_blank" moz-do-not-send="true">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" moz-do-not-send="true">qgis-user@lists.osgeo.org</a><br>
<b>Subject:</b> Re: [Qgis-user] finding the radius of
a curve</span></p>
<p class="MsoNormal"> </p>
<div>
<p class="MsoNormal">I'll give it a try. Thanks!</p>
</div>
<p class="MsoNormal"> </p>
<div>
<div>
<p class="MsoNormal">On Sun, Apr 14, 2019 at 7:52 AM
Mike Flannigan <<a href="mailto:mikeflan@att.net"
target="_blank" moz-do-not-send="true">mikeflan@att.net</a>>
wrote:</p>
</div>
<blockquote
style="border-top:none;border-right:none;border-bottom:none;border-left:1pt
solid rgb(204,204,204);padding:0cm 0cm 0cm
6pt;margin-left:4.8pt;margin-right:0cm">
<p class="MsoNormal" style="margin-bottom:12pt"><br>
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" moz-do-not-send="true">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" moz-do-not-send="true">
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!</p>
</blockquote>
</div>
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</blockquote>
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