Excellent,<br><div class="gmail_quote"><div class="gmail_quote"><div class="Ih2E3d"><br>Thank you both, very helpful, all working!<br>
<br></div><div><div></div><div class="Wj3C7c">Joe<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><br><br><div class="gmail_quote"><div>
<div></div><div>On Sun, Jun 22, 2008 at 10:20 PM, Paragon Corporation <<a href="mailto:lr@pcorp.us" target="_blank">lr@pcorp.us</a>> wrote:<br>
</div></div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><div><div></div><div>
<div>
<div dir="ltr" align="left"><span><font color="#0000ff" size="2" face="Arial">Joe,</font></span></div>
<div dir="ltr" align="left"><span><font color="#0000ff" size="2" face="Arial">You need to convert to some sort of foot or meter
projection that is suitable for your area of interest. your measures are
in degrees.</font></span></div>
<div dir="ltr" align="left"><span><font color="#0000ff" size="2" face="Arial"></font></span> </div>
<div dir="ltr" align="left"><span><font color="#0000ff" size="2" face="Arial">Then once you've figured out the SRID of that - then
transform</font></span></div>
<div dir="ltr" align="left"><span><font color="#0000ff" size="2" face="Arial"></font></span> </div>
<div dir="ltr" align="left"><span>SELECT
ST_Length(St_MakeLine(ST_Transform(point,rightsridgoeshere))))/1000 as
distance<div><br>
<div>FROM (<br> SELECT point
FROM points<br> ORDER BY timestamp<br>) as
p</div></div></span></div>
<div> </div>
<div><font color="#0000ff" size="2" face="Arial"></font> </div>
<div><span></span><font face="Arial"><font color="#0000ff"><font size="2">S<span>ome good places to
figure this out</span></font></font></font></div>
<div><font face="Arial"><font color="#0000ff"><font size="2"><span>1) PostGIS Wiki</span></font></font></font></div>
<div><font face="Arial"><font color="#0000ff"><font size="2"><span><a href="http://postgis.refractions.net/support/wiki/index.php?plpgsqlfunctions" target="_blank">http://postgis.refractions.net/support/wiki/index.php?plpgsqlfunctions</a></span></font></font></font></div>
<div><font face="Arial"><font color="#0000ff"><font size="2"><span></span></font></font></font> </div>
<div><font face="Arial"><font color="#0000ff"><font size="2"><span>There is a function that given a point with a defined
SRID (not -1) will give you the SRID of the UTM zone for that
point</span></font></font></font></div>
<div><font face="Arial"><font color="#0000ff"><font size="2"><span></span></font></font></font> </div>
<div><font face="Arial"><font color="#0000ff"><font size="2"><span>2) <a href="http://spatialreference.org/" target="_blank">http://spatialreference.org/</a></span></font></font></font></div>
<div><font face="Arial"><font color="#0000ff"><font size="2"><span></span></font></font></font> </div>
<div><font face="Arial"><font color="#0000ff"><font size="2"><span>Has a plethora of options and search to find the
spatial ref that works best for you.</span></font></font></font></div>
<div><font face="Arial"><font color="#0000ff"><font size="2"><span></span></font></font></font> </div>
<div><font face="Arial"><font color="#0000ff"><font size="2"><span>Hope that helps,</span></font></font></font></div>
<div><font face="Arial"><font color="#0000ff"><font size="2"><span>Regina</span></font></font></font></div>
<div><font face="Arial"><font color="#0000ff"><font size="2"><span></span></font></font></font> </div>
<div><font face="Arial"><font color="#0000ff"><font size="2"><span></span></font></font></font> </div>
<div><br></div>
<div dir="ltr" align="left" lang="en-us">
<hr>
<font size="2" face="Tahoma"><b>From:</b>
<a href="mailto:postgis-users-bounces@postgis.refractions.net" target="_blank">postgis-users-bounces@postgis.refractions.net</a>
[mailto:<a href="mailto:postgis-users-bounces@postgis.refractions.net" target="_blank">postgis-users-bounces@postgis.refractions.net</a>] <b>On Behalf Of </b>Joe
Roberts<br><b>Sent:</b> Sunday, June 22, 2008 4:11 PM<br><b>To:</b>
<a href="mailto:postgis-users@postgis.refractions.net" target="_blank">postgis-users@postgis.refractions.net</a><br><b>Subject:</b> [postgis-users] Newbie
- get total distance travelled from query ofpoints<br></font><br></div><div><div></div><div>
<div></div>Hi,<br><br>I am very new to PostGIS, and I'm stuck with what I hope
is an easy<br>problem to solve.<br><br>I have a table which contains a list of
points, originating from a GPS<br>device's lat/long output. I want to get the
distance travelled. I have<br>the following query, but the result (distance)
looks far to low:<br><br>SELECT ST_Length(St_MakeLine(point))/1000 as
distance<br>
<div>FROM (<br> SELECT point
FROM points<br> ORDER BY timestamp<br>) as p<br><br>I know
the route was over 5 miles (probably about about 8.4 km), but<br>the query
returns 0.000106496.<br><br>Can anyone see what I am doing wrong? Is it my
query, or could it be<br>my data?<br><br>Many
thanks<br><br>Joe</div></div></div></div>
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<br></blockquote></div><br>
</blockquote></div></div></div><br>
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