[pgrouting-users] Reg: Get nearest node in osm data

[Manikanta Kondeti]

Hi Steve,

Thanks a lot for your response.

On Wed, Jun 24, 2015 at 1:55 AM, Stephen Woodbridge <woodbri at swoodbridge.com
> wrote:

> On 6/23/2015 3:56 PM, Manikanta Kondeti wrote:
>
>> Hi,
>>
>>   I am writing a small application to get the route on the map. I am
>> using openlayers.js on client and pgrouting as a backend routing library
>> for my project. When a click is triggered I get a lat, lon, and I have
>> the osm data in postgres which is loaded using osm2pgrouting. I'll pass
>> this lat,lon to server and  I have to find the nearest node id from this
>> lat,lon. Can I query the database and get it done?  Help me out.
>>
>
> Probably you want to do this in two steps:
>
> 1. find the nearest edge
> 2. find the nearest node along the edge
>
> Anyway your queries will be something like:
>

This is working perfect and found the nearest edge.


> -- get the closest edge
> select * from edges where st_dwithin(geom, st_setsrid(st_makepoint(long,
> lat), 4326), maxdist) order by st_distance(geom,
> st_setsrid(st_makepoint(long, lat), 4326)) asc limit 1;
>
>
This is giving me syntax error. I've added the screenshot


> -- get closest node along edge
> select case when st_line_locate_point(geom,st_setsrid(st_makepoint(long,
> lat), 4326))  < 0.5 then source else target from edges edge_id=id
>
>
>
>
This is not giving me any nearest nodes. I've this screenshot as well.


> -- or search to just get the closest node
> select * from nodes where st_dwithin(geom, st_setsrid(st_makepoint(long,
> lat), 4326), maxdist) order by st_distance(geom,
> st_setsrid(st_makepoint(long, lat), 4326)) asc limit 1;
>
>
> where:
>
> maxdist - maximum distance to search for geometries in db units probably
> degrees
>
> long, lat - values for the location in question
>
> id - is the id of the closest edge found in the first query
>



Let me know if I miss something.

Thanks,
Mani



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