Now you do your make line. But you'll have to take into consideration what Paolo Rizzi said afterward. Not sure the easiest way to do that. So basically your process should look something like the below where trip_id is some fied that uniquely identifies each trip. The below snaps each point to closest road segment and then makes a line for each trip. It assumes the pt.gid is in the order of time travel. If you have a datetime field for each point, use that instead of the pt.gid. SELECT trip_id, ST_MakeLine(snapped_point) As trip_route (SELECT pt_id, ln_id,
ST_Line_Interpolate_Point( ln_geom, ST_Line_Locate_Point(ln_geom, pt_geom) ) As snapped_point, travel_id FROM ( SELECT DISTINCT ON (pt.gid) ln.the_geom AS ln_geom, pt.the_geom AS pt_geom, ln.id AS ln_id, pt.gid AS pt_id,pt.trip_id FROM gps_points pt INNER JOIN road_table ln ON ST_DWithin(pt.the_geom, ln.the_geom, 10.0) ORDER BY pt.gid,ST_Distance(ln.the_geom, pt.the_geom) ) AS subquery ORDER BY trip_id, pt_id) As snapped_points GROUP BY travel_id; Hope that helps, Regina ________________________________ From: [EMAIL PROTECTED] on behalf of searchelite Sent: Thu 7/17/2008 10:23 AM To: postgis-users@postgis.refractions.net Subject: RE: [postgis-users] match line with road segment Paragon Corporation-2 wrote: > > You may be better off snapping the points to the line first before you do > a > make line. Take a look at Paul's blog entry. > > > http://blog.cleverelephant.ca/2008/04/snapping-points-in-postgis.html > > Sounds similar to what you are trying to do. > > Hope that helps, > Regina > > Thanks for the reply...Yes, I already did that (snapping the point to the line)..so, is there any idea what should i do next? thanks -- View this message in context: http://www.nabble.com/match-line-with-road-segment-tp18479996p18509643.html Sent from the PostGIS - User mailing list archive at Nabble.com. _______________________________________________ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users ----------------------------------------- The substance of this message, including any attachments, may be confidential, legally privileged and/or exempt from disclosure pursuant to Massachusetts law. It is intended solely for the addressee. If you received this in error, please contact the sender and delete the material from any computer.
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