Linked Questions

6
votes
4answers
655 views

Drawing lines to nearest points in QGIS

I have two point layers, one with telecom towers and another with secondary schools. I have used the NNJoin Plugin to find the nearest tower from each school, and calculated the distance between. The ...
0
votes
1answer
348 views

Pois_close POINT with postgis and rails

I try to use postgis in rails and write my first request. I would like have : - the nearest points of another point (but without this point) - the name and the distance between the both In my model I ...
3
votes
1answer
56 views

Pgrouting: problem with pgr_withpointsDD

I'd like to calculate a propagation from sources using my road graph. In extenso, I'd like to answer the following question: where are the limits of my isochrones for every sources I got. My sources (...
7
votes
4answers
2k views

Finding distance between buildings and nearest road using QGIS

I am very new to working with GIS data. I am currently using the QGIS tool to work with the data. I have two datasets: Buildings - polygon shapefile with information about different buildings in a ...
1
vote
1answer
24 views

pgrouting/PostGIS Trying to set nearest node to airports in a region brings the same node for each airport

I need to make a distance matrix from all the nodes in the Canary Islands to every airport in the region. I'm following the method set here but it brings the same node for all airports. Trying the ...
4
votes
1answer
704 views

Calculating nearest neighbor within each polygon using QGIS?

I have 3 layers: world map divided into countries; layer of points representing cities; layer of points representing conflict events (e.g. firefight). My goal: For each city, calculate the nearest ...
1
vote
0answers
56 views

KNN with “Big Data”

I have a point dataset of over 30mill records and I am trying to select the closest 5 lines to each point. Reading this post there seems to be two methodologies Using <-> however as I want to ...
2
votes
1answer
79 views

Calculating distance between every entry in Table A and nearest record in Table B using PostGIS

I am new to PostGIS. How do I calculate the distance and direction between every site (approx 30,000 record) and the nearest entity in a gazetteer (approx 300,000 records)? Ideally a separate table ...
2
votes
1answer
363 views

Fastest matching on nearest point

I am a total GIS noob and am trying to read weather data from a PostGIS database. The tables contain data points consisting of a geometry, a timestamp and the actual observed variable. The tables are ...
2
votes
1answer
549 views

Find nearest point given coordinates from another table [duplicate]

So I have two tables, one table is called stores which has the name of the store as well as the geom column that contains the coordinates for the stores. The other table is customers which has the ...
2
votes
1answer
955 views

Nearest Neighbour function

I'm trying to create a function which calculates the nearest neighbors under a certain length in a table s_1 an stores them in an output table. This is what I've got so far: CREATE OR REPLACE ...
4
votes
1answer
2k views

Using st_distance to calculate shortest distance between a table with point geometry to a table with multipolygon geometry

I'm trying and failing to do a calculation of the shortest distance for each point in a point geometry table (15000 records) to the nearest polygon edge in another table (170000 records). The end ...
5
votes
1answer
2k views

PostGIS nearest point with LATERAL JOIN in PostgreSQL 9.3+

I need to obtain on each element on one table the closest point of another table. The first table contains traffic signs and the second one the Entrance Halls of the town. The thing is that I can't ...
1
vote
1answer
526 views

Where to store lat/lon data with additional informations?

I have huge database of lat/lon GPS coordinate points. For every point, I have several other variables (height, surface type, temperature, pressure...). Also, data will be changed every day and old ...
1
vote
0answers
51 views

find nearest point to a point in another table

This similar, but not quite the same as this question. I need to pick, regardless of distance, the closest 'n' points to a given point in another table, using postGIS. Imagine a table with city ...