Tagged Questions

1
vote
1answer
95 views

Accurate and fast nearest neighbour, which distance function should I use and how to it speed up? [duplicate]

I am solving the following problem: I have a map with many points in it and I need to find the nearest point to given location. Each point carries information about it's latitude and longitude. This ...
1
vote
1answer
125 views

What format is lat/long stored in OSM PostGIS?

Question: How do I to get the lat, long for all the toll booths stored in OSM for Virginia? Current Query: > gis=# select * from planet_osm_nodes where ('toll_booth' = ANY(tags)); id ...
2
votes
1answer
209 views

How can I get the corners of a polygon in latitude and longitude?

How can I get the corners of a polygon -a square/rectangle, to be precise- in latitude-longitude format by using its geom value -or some other way, perhaps-? Thanks.
0
votes
0answers
15 views

Using PostGIS to create a grid map and count points in grids [duplicate]

Possible Duplicate: How to create a regular polygon grid in PostGIS? I'm trying to divide the map of an area into 1 km x 1 km square grids and ultimately, count and retrieve how many points ...
2
votes
2answers
1k views

Problem when calculating longitude and latitude for points

I have a PostGIS database with SRID=900913 (Google Mercator) and I would like to know the latitude and longitude of points. I use this command: ST_X(ST_TRANSFORM(the_geom,4283)) Following what is ...