<table cellspacing="0" cellpadding="0" border="0"><tr><td valign="top" style="font: inherit;"><p>Hi Chris</p>
<p>You need an inner query that selects the closest line segment and use that geometry in the shortest line query <br>
Select shrtest line(p.the_geom,nearestgeom.thegeom) from<br>
Points p,<br>
Select  a.*, st_distance(a.the_geom, b.the_geom) as dist from roads a,points b order by dist asc limit 1) as nearestgeom</p>
<p>Hope this is readable as sending from phone.</p>
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                                <span style="font-weight:bold;">From:</span>
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                            Chris English <sglish@hotmail.com>;                            <br>
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                                <span style="font-weight:bold:">To:</span>
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                             <postgis-users@postgis.refractions.net>;                                                                                                     <br>
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                                <span style="font-weight:bold:">Subject:</span>
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                            [postgis-users] ST_ShortestLine(r.geom, m.geom) confusion - limiting  point to nearest line results                            <br>
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                                <span style="font-weight:bold;">Sent:</span>
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                            Mon, Nov 21, 2011 9:00:47 PM                            <br>
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<div dir="ltr">Hi all,<div><br></div><div>My goal is to model electric distribution in a municipality with 8.4, PostGis 1.5 and pgrouting.</div><div><br></div><div>I clipped roads and parcels from state level (roads) and county level (parcels) to get roads and parcels for</div><div>a municipality resulting in two tables:</div><div><br></div><div>summit_roads (306 rows) and summit_parcels (6874 rows) . </div><div>The roads table generally conforms to the layout of electric distribution.</div><div>I then extracted a centroids table from parcels to try to develop the 'final drop' line segment, the last bit of wire from</div><div>distribution wire (roads) to a home or business with the final goal to then join to final drop to roads for end to end distribution.</div><div><br></div><div><div><br></div><div>explain </div><div>create table summit_final_drop as</div><div>select Distinct ST_ShortestLine(r.intersection_geom, m.geom) as
 final_drop_geom,</div><div>r.sld_name,</div><div>r.measured_l,</div><div>m.pams_pin,</div><div>m.mun,</div><div>m.block,</div><div>m.lot,</div><div>m.qcode</div><div>from summit_roads as r,</div><div>summit_parcels_centroid as m;</div></div><div><br></div><div>This code resulted in 2,109,000 rows , essentially centroid to every line point as against what</div><div>I was expecting.</div><div><br></div><div>Suggestions appreciated.</div><div><br></div><div>Thanks,</div><div>Chris</div></div>
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