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<DIV dir=ltr align=left><SPAN class=102324810-19032008><FONT face=Arial
color=#0000ff size=2>You'll need to transform to a meter based projection to do
that. If for example you are in the U.S, SRID 2163 US National Atlas Equal
Area works pretty good for measurement. It is not as accurate as UTM
or State Plane, but its pretty good and covers all of US I believe and probably
works for some of Canada as well (not sure about non-continental e.g.
Hawaii, Alaska). </FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=102324810-19032008><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=102324810-19032008><FONT face=Arial
color=#0000ff size=2>
<DIV dir=ltr align=left><SPAN class=102324810-19032008><FONT face=Arial
color=#0000ff size=2>e.g.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=102324810-19032008><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=102324810-19032008><FONT face=Arial
color=#0000ff size=2>SELECT road.rd_name, ht.ht_name,
ST_Distance(ST_Transform(roads.the_geom,2163) ,
ST_Transform(hotel.the_geom,2163)) as dist_meters</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=102324810-19032008><FONT face=Arial
color=#0000ff size=2>FROM road, hotel</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=102324810-19032008><FONT face=Arial
color=#0000ff size=2>WHERE <some criteria
here></FONT></SPAN></DIV></FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=102324810-19032008><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=102324810-19032008><FONT face=Arial
color=#0000ff size=2>If you are somewhere else and your locations are within
that projection, you can use that. Look at the utmzone function in
the wiki that will help you determing the right UTM zone SRID for your
data</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=102324810-19032008><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=102324810-19032008><FONT face=Arial
color=#0000ff size=2><A
href="http://postgis.refractions.net/support/wiki/index.php?plpgsqlfunctions">http://postgis.refractions.net/support/wiki/index.php?plpgsqlfunctions</A></FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=102324810-19032008><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=102324810-19032008><FONT face=Arial
color=#0000ff size=2>So you would use something liek</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=102324810-19032008><FONT face=Arial
color=#0000ff size=2>SELECT utmzone(ST_Centroid(the_geom)) as
srid</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=102324810-19032008><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=102324810-19032008><FONT face=Arial
color=#0000ff size=2>to get the right UTM zone SRID</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=102324810-19032008><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=102324810-19032008><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=102324810-19032008><FONT face=Arial
color=#0000ff size=2>Hope that helps,</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=102324810-19032008><FONT face=Arial
color=#0000ff size=2>Regina</FONT></SPAN></DIV>
<DIV><SPAN class=102324810-19032008><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=102324810-19032008><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><BR></DIV>
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left>
<HR tabIndex=-1>
<FONT face=Tahoma size=2><B>From:</B>
postgis-users-bounces@postgis.refractions.net
[mailto:postgis-users-bounces@postgis.refractions.net] <B>On Behalf Of
</B>Sinboy Chang<BR><B>Sent:</B> Wednesday, March 19, 2008 3:09 AM<BR><B>To:</B>
postgis-users@postgis.refractions.net<BR><B>Subject:</B> [postgis-users] How to
get the distance between geometry in meters?<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV>i want to get the distance between geometry,just like road or
hotel poi,but ST_Distance() return the result in <EM>cartesian
dintance.</EM></DIV>
<DIV>So how can get the distance() by meters?</DIV></BODY></HTML>
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