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<div class="moz-cite-prefix">Dear Andreas, Horst<br>
Thanks a lot for your answers, it's perfect.<br>
Maybe it could be interesting to insert this kind of things in the
documentation ?<br>
Ludovic<br>
<br>
Le 19/11/2013 17:29, Horst Düster a écrit :<br>
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Hi Ludovic
The number of segments depends on the exactness of the results you
expect. If you create a circle buffer around a point with radius of 1
the area of the circle will running against PI with increasing number of
segments. Now you have to decide how many digits of PI are expected as
exact.
mPoint = QgsGeometry().fromPoint(QgsPoint(0,0))
for i in range(100):
circle = mPoint.buffer(1,i+1)
print str(i)+" "+str(circle.area())
All the best
Horst
Dr. Horst Düster
Kappasys
Alte Bernstrasse 13
CH-4500 Solothurn
Tel.: +41 (0) 32 514 00 40
Mobil: +41 (0) 76 408 51 06
eMail: <a class="moz-txt-link-abbreviated" href="mailto:horst.duester@kappasys.ch">horst.duester@kappasys.ch</a>
skype: horstduester
Twitter: moazagotl
Web: <a class="moz-txt-link-abbreviated" href="http://www.kappasys.ch">www.kappasys.ch</a>
qgiscloud.com - The easiest way to publish your maps
Am 19.11.2013 17:07, schrieb Andreas Neumann:
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<pre wrap="">Hi,
Buffers for points are round. There are also round corners for
</pre>
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<pre wrap="">line/polygon buffers, depending on the linecap styles and line join
styles. QGIS and simple features can only display straight lines. The
number of the segements to approximate means the higher the number, the
more vertices you will have for a circle approximation.
</pre>
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See also <a class="moz-txt-link-freetext" href="http://postgis.net/docs/manual-2.1/ST_Buffer.html">http://postgis.net/docs/manual-2.1/ST_Buffer.html</a> as an
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<pre wrap="">explanation for buffer styles and segments.
</pre>
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<pre wrap="">
Andreas
Am 2013-11-19 14:57, schrieb ludo:
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<pre wrap="">Hi all
Is there anyone could tell me what is "segments to approximate" in the
buffer tool ?
I know that if I increase this value, there's more nodes on my buffer
but I don't know what is it exactly and how we can choose this value.
Thanks
Regards
Ludovic
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