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seen Jan 3 '13 at 12:17

Java, Android


Aug
14
awarded  Notable Question
Dec
28
awarded  Popular Question
May
4
comment Calculate distance of point from an arc/polyline
@NathanW Can ill upload it in a few
May
4
comment Calculate distance of point from an arc/polyline
@NicklasAvén Exactly.. I have looked at that link that you recommended on BostonGIS and it seems it could work. Now all i have to do is to construct the query for PostgreSQL. Thank you
May
4
comment Calculate distance of point from an arc/polyline
I have a database of nodes and arcs. Nodes are GPS coordinates of where roads intersect. The arcs depict the road network between these nodes i.e they make the road network.
May
4
awarded  Commentator
May
4
comment Calculate distance of point from an arc/polyline
Im sorry if i might have misled you. I am creating an application that detects traffic congestion by calculating how far you have moved over a period of time. To do this i need to identify on which road segment a GPS device is on after every unit time. I just need to determine the road(defined as an arc in my database) where the device is on. Where the distance is shortest it means the device is most probably on that road
May
4
asked Determine the Closest road to a GPS point
May
3
comment Calculate distance of point from an arc/polyline
And maybe i should mention i already have these lines/edges and they are not necessarily straight as they are of a road network. is this operation still possible? Because from the solutions am getting, the assumption is that this is a straight line. Thank you in advance
May
3
awarded  Scholar
May
3
comment Calculate distance of point from an arc/polyline
I have finally gotten the query to run but i realized that we were creating our own arc. I have a database of these arcs that are defined by the route_database. How do i go about this?
May
3
comment Calculate distance of point from an arc/polyline
I tried the query in my database and rewrote it as follows "SELECT dist, the_edge FROM (SELECT ST_Distance( route_arc.recid, 'POINT(-1.23612463 36.79313278)') as dist, the_edge FROM(SELECT ST_MakeLine(a.nodeid, b.nodeid) AS the_edge FROM route_node AS a INNER JOIN route_node AS b ON b.gid=(a.gid+1)) e) s ORDER BY dist LIMIT 1"; I keep getting the following error function st_makeline(double precision, double precision) does not exist LINE 8: SELECT ST_MakeLine(a.nodeid, b.nodeid) AS the_ed... ^ Where am i going wrong? Plus the 'e' and 's' at the end are for looping right?
May
2
comment Calculate distance of point from an arc/polyline
Thank you so much for your Help Nicklas. I will tell you how it goes. I am looking forward to your continued support. Do you have an email address we can continue discussing this issue?
May
2
awarded  Supporter
May
2
comment Calculate distance of point from an arc/polyline
That seems to be very helpful. Could you please explain the query. I am a newbie to Postgres SQl i started using it recently for the PostGIS capability. I have understood WKT but how do b.geom and co. work?
May
2
comment Calculate distance of point from an arc/polyline
I want to have an efficient query that determines the edge to which a point is closest to
May
2
comment Calculate distance of point from an arc/polyline
Thank you for your comment. I am using some shape files that have two tables nodes and arcs. The node one contains gps coordinates of where roads intersect and the Arc table contains info on the arcs between this nodes. Is there a way to have a single query that could determine the arc closest to that GPS point?
May
2
comment Calculate distance of point from an arc/polyline
Thank you for your help. I have seen viewed the link posted and to be honest i do not see where i can specify my own GPS point in the query. Could you please rewrite the query with user input GPS points. I have imported a Shape file using POSTGIS. The shapefile comprises of two tables, Arcs and Nodes. The arcs are just specified using the nodes. I need to query the database the closest arc. Thank you
May
2
awarded  Student
May
2
asked Calculate distance of point from an arc/polyline