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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>The third parameter defines how close to a
circle the buffer will be. There is no “circle” in PostGIS (or
most GIS software) – it is approximated by a series of lines. The
default value of 8 means a circle will be approximated by 32 line segments. If
you specified this as 1 you would get 4 points or a square. If the buffer
value is very large you might need to increase the value to more than 8.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Bruce<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>
postgis-users-bounces@postgis.refractions.net
[mailto:postgis-users-bounces@postgis.refractions.net] <b><span
style='font-weight:bold'>On Behalf Of </span></b>Pedro Doria Meunier<br>
<b><span style='font-weight:bold'>Sent:</span></b> Saturday, December 02, 2006
10:13 AM<br>
<b><span style='font-weight:bold'>To:</span></b> '<st1:PersonName w:st="on">PostGIS
Users Discussion</st1:PersonName>'<br>
<b><span style='font-weight:bold'>Subject:</span></b> RE: [postgis-users] what
is the units of distance parameter inthe buffer function</span></font><o:p></o:p></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=PT
style='font-size:11.0pt;font-family:Calibri;color:#1F497D'>Kumar,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=PT
style='font-size:11.0pt;font-family:Calibri;color:#1F497D'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span
style='font-size:11.0pt;font-family:Calibri;color:#1F497D'>If your geom is
lat/lon 1=1 degree<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span
style='font-size:11.0pt;font-family:Calibri;color:#1F497D'>As to the 3<sup>rd</sup>
argument it’s a mystery to me too…<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span
style='font-size:11.0pt;font-family:Calibri;color:#1F497D'>From the manual:<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><i><font size=2
face="Times New Roman"><span style='font-size:10.0pt;font-style:italic'>The
optional third parameter sets the number<o:p></o:p></span></font></i></p>
<p class=MsoNormal style='text-autospace:none'><i><font size=2
face="Times New Roman"><span style='font-size:10.0pt;font-style:italic'>of
segment used to approximate a quarter circle (defaults<o:p></o:p></span></font></i></p>
<p class=MsoNormal><i><font size=2 face="Times New Roman"><span lang=PT
style='font-size:10.0pt;font-style:italic'>to 8).<o:p></o:p></span></font></i></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span
style='font-size:11.0pt;font-family:Calibri;color:#1F497D'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span
style='font-size:11.0pt;font-family:Calibri;color:#1F497D'>What’s this
good for?!<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span
style='font-size:11.0pt;font-family:Calibri;color:#1F497D'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span
style='font-size:11.0pt;font-family:Calibri;color:#1F497D'>Pedro.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span
style='font-size:11.0pt;font-family:Calibri;color:#1F497D'><o:p> </o:p></span></font></p>
<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>
<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>
postgis-users-bounces@postgis.refractions.net
[mailto:postgis-users-bounces@postgis.refractions.net] <b><span
style='font-weight:bold'>On Behalf Of </span></b>Sandeep Kumar Jakkaraju<br>
<b><span style='font-weight:bold'>Sent:</span></b> sábado, 2 de Dezembro de
2006 16:38<br>
<b><span style='font-weight:bold'>To:</span></b>
postgis-users@postgis.refractions.net<br>
<b><span style='font-weight:bold'>Subject:</span></b> [postgis-users] what is
the units of distance parameter in the buffer function<o:p></o:p></span></font></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span lang=PT
style='font-size:12.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span lang=PT
style='font-size:12.0pt'><br>
what is the units of distance parameter in the buffer function ...<br>
<br>
buffer(geom,distance,[integer]) --->
buffer(GEOMFROMTEXT('POINT(28.0 79.0)'),1);<br>
<br>
if my geom is in lat/lon ..... how much will be 1 !! <br>
<br>
can some one throw more light on the 3 rd optional parameter !!! the manual is
not clear !! <br>
<br>
-- <br>
Sandeep Kumar Jakkaraju <br>
WeBlog:<br>
<a href="http://jakkarajus.blogspot.com">http://jakkarajus.blogspot.com </a><o:p></o:p></span></font></p>
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