# Tagged Questions

16 views

### Calculate distance between point and linestring, save the distance as table and represent that on QGIS? [duplicate]

I have loaded my data with osm2pgrouting and I have my network with ways (Linestring) and nodes (Point). The problem is : I have a database of doctors addresses (point) and I should calculate the ...
39 views

### Calculate distance between point and linestring and how to represent that on QGIS?

I have loaded my data with osm2pgrouting and I have my network with ways (Linestring) and nodes (Point). The problem is : I have a database of doctors addresses (point) and I should calculate the ...
67 views

### Distance calculation PostGIS

I've got the following task to solve: I've got two tables; one contains buildings (houses) as points and the other contains train-stations (at_bhf_classified) as points. I need to find out the ...
227 views

### clustering points in postgresql to create contour map

UPDATE: To try to make this a little more simple, is it possible to create a query which selects a group of points such that each point in the group is at most X units away from at least one other ...
121 views

### using PostGIS to calculate distance of a route over a large area

I'm new to PostGIS and looking to measure the distance of the Pacific Crest Trail which spans western North America from Canada to Mexico. I have a data set containing the lat lon and dates from GPX ...
165 views

### Proximity search: ST_DWithin vs ST_Distance?

I have records stored in a table with latitude/longitude coordinates stored in a geometry field. I want to find all records nearby a user supplied reference point. Note "nearby" probably means less ...
381 views

### Postgis, get the points that are x meters near another point, in meters

I'm trying to find the points within a certain distance, in meters, from another point. I'm using the function ST_Buffer, but I don't get how to express the distance in meters. I'm trying with ...
249 views

### How to calculate the azimuth of a line of a multilinestring in PostGIS?

I have two spatially enabled tables in PostgreSQL with a geometry in each: First table is with POINT type, second is with MULTILINESTRING. I need to calculate the azimuth of the LINESTRING part of a ...
548 views

### Return all results within a 30km radius of a specific lat/long point?

I have a table with a column the_geom which contains data similar to: ...
44 views

### Can distance be calculated to a destination feature based on an attribute in the source?

All, Is it possible to specify which destination point to calculate distance to based on an attribute in the source? STDistance will give me the distance each student (point) is to their closest ...
27 views

### Bounding Boxes around nearby points [duplicate]

I've got a table with 200.000 points. My aim is to draw bounding boxes around points where this point have the same name and that are in a maximum distance of 500 meters to each other. I guess I can ...
192 views

### Mimimum distance between points (Postgres/PostGIS)

I have a table (tab_Cities with cities which own more than 50000 inhabitants. The table also contains lat, long and the_geom as columns. I can already see the points via QGIS. Now I want to write a ...
241 views

### Finding points along a path

I am unsure of the best approach to this problem. I can think of some ways of doing it which I will list below but I am looking for the best and most efficient way of doing this. Problem Given a ...
100 views

### How to visualise “distance from amenities”?

I'm interested in calculating for every point the distance to the nearest amenity of each of a certain number of types (train station, supermarket and so on). I think the calculation will be ...
85 views

### PostGIS integer loop

PostGIS is very new to me, and I'm having difficulty performing an operation that probably isn't too difficult. I have vector layers each filled with the outline of a landmass through time. I want to ...
281 views

### Why is sum of st_length() of segments 20% too big?

I'm running a query to return the total length of some bike paths, from OpenStreetMap. Compared to the known actual length of these paths, they're all a bit too big - something like 10-30%. I know it ...
46 views

### windows function with points in a mixed (multipoint/point) table

I have a table comprising multipoints (tracks) and points (stops between tracks). there can be several consecutive multipoints. now, i want to merge any points lying very closely to each other ...
789 views

### Distance between DB field and Point using PostGIS

I'm using Postgresql 9.0 with PostGIS 2.0 extension. I've got the table and geographic field location: =# SELECT * FROM geography_columns; f_table_catalog | f_table_schema | f_table_name | ...
497 views

### ST_Distance is not delivering right results

I want to calculate the distance between lat/lon points. I tried the following queries: Select ST_DISTANCE(ST_GeomFromText('POINT(-73.97923 40.75571)', 4326), ST_GeomFromText('POINT(-73.974509 ...
859 views

### postgis distance calculation between points with lat, long coordinates

Team, I am new to postgis, but a postgres user for quite a while. I would like to compare the geospatial capabilities between postgresql and mongodb. I have the lat.lon, zip code of US locations; ...
366 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 ...
484 views

### How to calculate the “depth” of a linestring using postgis

I have linestring features, which look like bent linestrings, hemicycles or convex or concave linestrings. In the moment I can select the distance between the startpoint and endpoint of each feature. ...
111 views

### How to find features within a distance? [duplicate]

I insert the values from lat/long into the points. Those users move around and send me new Lat/long and of course , I made an update of the position. I need to find people that are in a distance ...
889 views

### Calculate min distance between points in PostGIS

I have point layer in PostGIS database. Help please with query which add for each points in layer distance in attribute table between this point and another nearest point. Thanks! Update Calculate ...
22 views

### How to perform a join on simultaneous spatial and attribute criteria in PostGIS [duplicate]

Possible Duplicate: How to perform a join on simultaneous spatial and attribute criteria in ArcGIS? I have two point layers and want to perform a spatial join on nearest distance. I have a ...
483 views

### Getting points within a range from a postgres database?

ok so this is query i'm making which returns no result: SELECT building.gid FROM building WHERE ST_Dwithin(building.geom, ST_GeomFromText('POINT(long lat)',4326), 400) If I run this ...
297 views

### PgRouting Driving Distance crashing postgis server

I haven't used PgRouting much so I'm a little in the dark here. However, I am attempting a driving distance calculation like the one described by Underdark here. My SQL is identical, I have a ...
431 views

### Implementing custom (Vincenty/Haversine formula) functions for MySQL vs Using PostGIS?

I currently am using MySQL for all of my relational data. I have hit a crossroads with geo calculations. Since, MySQL does not have good support for spatial functions, I am contemplating on using ...
709 views

### MySQL GeoSpatial function for ST_Distance_Spheroid? Metric used in return Type of GLength?

Is there a ST_Distance_Sphere, ST_Distance_Spheroid equivalent function in MySQL's GeoSpatial Support? If not, any way to emulate this? What is the metric used in return type of ...
777 views

### PostGIS - Calculate progressive distance between points on a GPX path

I am attempting to build an elevation profile using PostGIS-PostgreSQL only. I have imported GPX data in my PostGis database, so now I have a table full of the GPS coordinates of the track and the ...
390 views

### PostGIS - table with 3d points with fast ordering by distance

I am pretty new to PostGIS and I am trying to solve the following problem. I need a table with 3D points (x,y,z) that will contain around 1-10million points. I want to be able to efficiently ask the ...
593 views

### How to find the two furthest points between a group of points?

I have a table with 20000 records and with those columns Shop, longitude, latitude, geom I would like to find a way to find the pair of ths farthest shops between a selection of shops For example we ...
2k views

### How do I get the distance meter value between two geometries in PostGIS?

I have a simple question about calculating distances in PostGIS. I would like to get the distance between two geometries. I am using this sid : 4269 in meters what i am doing now is this : ...
2k views

### How do I perform a proximity search with Postgis?

OK, so I downloaded the Geonames database (cities1000) and wrote a small Ruby program to import them into my table (geo_cities). I then added geography column called geog. So after all of that, I ...
4k views

### Simple PostGIS ST_Distance query for two points from the same geometry table?

Note: This question was published at Stackoverflow at first. I have a geometry table points_table with SRID 4326 and a few points in it. I need to find a distance between a pair of points (features) ...
659 views

### Total great circle distance along a path of points (PostGIS)

I am looking for an SQL query that sums the distances between a series of points using PostGIS. The situation is as follows: I have 2 tables: tracks and points. Points belong to a track and thus ...
710 views

### clip linestring by length

Is there a way to clip a linestring based on distance? For example, linestring from a to b is 150 meters. I would like to get the linestring from a to a point that is is 75 meters away from a ...
447 views

### How to efficiently find points within an elliptical area?

Using PostGIS 2.0.0 I need to filter the results of a function, which returns many POINTs, to find the ones that lie within an elliptical area defined by two points and a distance (all parameters ...
1k views

### ST_Distance versus ST_Distance_Spheroid?

As my client software uses lat/lon coordinates when communicating with my (spherical mercator) postgis database i decided to ST_Transform every geometry to WGS-84. However i noticed that ST_Distance ...
422 views

### PostGIS ST_Distance vs. pgRouting

I am looking to create a city directory web app, and the site will need to be able to calculate distances between two geospatial points (like the distance between the user and a restaurant, or the ...
812 views

### Distance between points and polygons in QGIS / PostGIS

I need to work out the distance between a table of polygons and a table of points. The table of polygons has different site boundaries, and the point table has points relating to each of the site ...