Question

I am new in Geo problems and need to ask about using PostGIS.
I imported OpenStreetMap data through osmosis into PgSQL and I need to query this data.

Essentially I have location from GPS and I need to get just all tags of Nodes, Ways and Areas that are at least from part within some distance from me (lets say 100 meters).

I do not really know where to start.

Thanks.

Answer 1

If you have a latitude and a longitude you could try something like the following:

select * from nodes_with_tags 
where st_distance(geography(geom), 
 geography(st_geomfromewkt('SRID=4326;POINT(' || lng || ' ' || lat || ')'))) 
  <= 100;

Converting with the ‘geography’ function slows things down but gives the distance in meters rather than unintelligible degrees.

You can also perform the same query on the ‘ways’ table, replacing ‘geom’ column with the ways.linestring column.