<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv=Content-Type content="text/html; charset=us-ascii">
<meta name=Generator content="Microsoft Word 12 (filtered medium)">
<style>
<!--
/* Font Definitions */
@font-face
{font-family:SimSun;
panose-1:2 1 6 0 3 1 1 1 1 1;}
@font-face
{font-family:SimSun;
panose-1:2 1 6 0 3 1 1 1 1 1;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
@font-face
{font-family:"\@SimSun";
panose-1:2 1 6 0 3 1 1 1 1 1;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0cm;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman","serif";}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
p
{mso-style-priority:99;
mso-margin-top-alt:auto;
margin-right:0cm;
mso-margin-bottom-alt:auto;
margin-left:0cm;
font-size:12.0pt;
font-family:"Times New Roman","serif";}
tt
{mso-style-priority:99;
font-family:"Courier New";}
span.EmailStyle19
{mso-style-type:personal-reply;
font-family:"Calibri","sans-serif";
color:#1F497D;}
.MsoChpDefault
{mso-style-type:export-only;}
@page WordSection1
{size:612.0pt 792.0pt;
margin:72.0pt 72.0pt 72.0pt 72.0pt;}
div.WordSection1
{page:WordSection1;}
-->
</style>
<!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang=EN-AU link=blue vlink=purple>
<div class=WordSection1>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>I think you can try to covert lat/longs to meters, but this is
highly inaccurate, especially in places where the latitude is greater than 75.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>This problem troubles us as well<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm'>
<p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:
"Tahoma","sans-serif"'>From:</span></b><span lang=EN-US style='font-size:10.0pt;
font-family:"Tahoma","sans-serif"'> postgis-users-bounces@postgis.refractions.net
[mailto:postgis-users-bounces@postgis.refractions.net] <b>On Behalf Of </b>Stefan
Priess<br>
<b>Sent:</b> Thursday, 8 July 2010 4:52 PM<br>
<b>To:</b> PostGIS Users Discussion<br>
<b>Subject:</b> [postgis-users] Antwort: Re: Projection(s) for global point-and-radius
searches<o:p></o:p></span></p>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><br>
<span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Hey Paul,</span>
<br>
<br>
<span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>i need the
ST_Expand() function with a radius/expand of 10 Meters, how i will do that?</span>
<br>
<span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>The Point to
expand is in SRID 4326 .</span> <br>
<br>
<span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Thanks</span> <br>
<br>
<span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Stefan<br>
</span><br>
<br>
<o:p></o:p></p>
<table class=MsoNormalTable border=0 cellpadding=0 width="100%"
style='width:100.0%'>
<tr>
<td width="40%" valign=top style='width:40.0%;padding:.75pt .75pt .75pt .75pt'>
<p class=MsoNormal><b><span style='font-size:7.5pt;font-family:"Arial","sans-serif"'>Paul
Ramsey <pramsey@opengeo.org></span></b><span style='font-size:7.5pt;
font-family:"Arial","sans-serif"'> </span><br>
<span style='font-size:7.5pt;font-family:"Arial","sans-serif"'>Gesendet von:
postgis-users-bounces@postgis.refractions.net</span> <o:p></o:p></p>
<p><span style='font-size:7.5pt;font-family:"Arial","sans-serif"'>07.07.2010
23:13</span> <o:p></o:p></p>
<table class=MsoNormalTable border=1 cellpadding=0>
<tr>
<td valign=top style='background:white;padding:.75pt .75pt .75pt .75pt'>
<p class=MsoNormal align=center style='text-align:center'><span
style='font-size:7.5pt;font-family:"Arial","sans-serif"'>Bitte antworten an<br>
PostGIS Users Discussion <postgis-users@postgis.refractions.net></span><o:p></o:p></p>
</td>
</tr>
</table>
</td>
<td width="59%" valign=top style='width:59.0%;padding:.75pt .75pt .75pt .75pt'>
<table class=MsoNormalTable border=0 cellpadding=0 width="100%"
style='width:100.0%'>
<tr>
<td valign=top style='padding:.75pt .75pt .75pt .75pt'>
<p class=MsoNormal align=right style='text-align:right'><span
style='font-size:7.5pt;font-family:"Arial","sans-serif"'>An</span><o:p></o:p></p>
</td>
<td valign=top style='padding:.75pt .75pt .75pt .75pt'>
<p class=MsoNormal><span style='font-size:7.5pt;font-family:"Arial","sans-serif"'>PostGIS
Users Discussion <postgis-users@postgis.refractions.net></span> <o:p></o:p></p>
</td>
</tr>
<tr>
<td valign=top style='padding:.75pt .75pt .75pt .75pt'>
<p class=MsoNormal align=right style='text-align:right'><span
style='font-size:7.5pt;font-family:"Arial","sans-serif"'>Kopie</span><o:p></o:p></p>
</td>
<td valign=top style='padding:.75pt .75pt .75pt .75pt'></td>
</tr>
<tr>
<td valign=top style='padding:.75pt .75pt .75pt .75pt'>
<p class=MsoNormal align=right style='text-align:right'><span
style='font-size:7.5pt;font-family:"Arial","sans-serif"'>Thema</span><o:p></o:p></p>
</td>
<td valign=top style='padding:.75pt .75pt .75pt .75pt'>
<p class=MsoNormal><span style='font-size:7.5pt;font-family:"Arial","sans-serif"'>Re:
[postgis-users] Projection(s) for global point-and-radius
searches</span><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>
</span><o:p></o:p></p>
</td>
</tr>
</table>
<p class=MsoNormal><o:p> </o:p></p>
<table class=MsoNormalTable border=0 cellpadding=0>
<tr>
<td valign=top style='padding:.75pt .75pt .75pt .75pt'></td>
<td valign=top style='padding:.75pt .75pt .75pt .75pt'></td>
</tr>
</table>
</td>
</tr>
</table>
<p class=MsoNormal style='margin-bottom:12.0pt'><br>
<br>
<br>
<tt><span style='font-size:10.0pt'>No, because the functions on Geometry(4326)
don't return metric answers.</span></tt><span style='font-size:10.0pt;
font-family:"Courier New"'><br>
<br>
<tt>SELECT</tt><br>
<tt> ST_Distance('SRID=4326;POINT(0 0)'::geometry, 'SRID=4326;POINT(1</tt><br>
<tt>1)'::geometry) as geom,</tt><br>
<tt> ST_Distance('POINT(0 0)'::geography, 'POINT(1 1)'::geography) as
geog;</tt><br>
<br>
<tt>Geography understands that it's on a sphere and does the Right Thing.</tt><br>
<tt>Geometry(4326) still operates on a cartesian plane, it just has</tt><br>
<tt>"units" of degrees (which is pretty nonsensical for any kind of</tt><br>
<tt>measurement calculation).</tt><br>
<br>
<tt>P</tt><br>
<br>
<tt>On Wed, Jul 7, 2010 at 2:03 PM, David Jantzen <djantzen@ql2.com>
wrote:</tt><br>
<tt>> Ok, interesting. Is it equivalent then to using a GEOMETRY type
with SRID 4326?</tt><br>
<tt>></tt><br>
<tt>> On Jul 7, 2010, at 12:25 PM, Paul Ramsey wrote:</tt><br>
<tt>></tt><br>
<tt>>> On Wed, Jul 7, 2010 at 12:25 PM, Paul Ramsey
<pramsey@opengeo.org> wrote:</tt><br>
<tt>>>> ST_Buffer(geography, float8) returns geography</tt><br>
<tt>>>> ST_Intersection(geography, geography) returns geography</tt><br>
<tt>>></tt><br>
<tt>>> These last two actually *do* carry out projections under the
covers,</tt><br>
<tt>>> so watch out.</tt><br>
<tt>>></tt><br>
<tt>>> P</tt><br>
<tt>>> _______________________________________________</tt><br>
<tt>>> postgis-users mailing list</tt><br>
<tt>>> postgis-users@postgis.refractions.net</tt><br>
<tt>>> http://postgis.refractions.net/mailman/listinfo/postgis-users</tt><br>
<tt>></tt><br>
<tt>> _______________________________________________</tt><br>
<tt>> postgis-users mailing list</tt><br>
<tt>> postgis-users@postgis.refractions.net</tt><br>
<tt>> http://postgis.refractions.net/mailman/listinfo/postgis-users</tt><br>
<tt>></tt><br>
<tt>_______________________________________________</tt><br>
<tt>postgis-users mailing list</tt><br>
<tt>postgis-users@postgis.refractions.net</tt><br>
<tt>http://postgis.refractions.net/mailman/listinfo/postgis-users</tt></span><o:p></o:p></p>
</div>
</body>
</html>