PostGIS is an extension for the PostgreSQL object-relational database that adds support for geographic objects.

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nearest facility with pgrouting

I have a postgres table of students with lat, lon and geom, , and a table of schools with the same, and a table of roads that has been converted to nodes. I'm trying to find the driving distance to ...
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663 views

PostGIS Raster in MapServer

I'm having trouble getting a PostGIS raster to load and display in MapServer. I'm not sure, but suspect it's a version problem. My mapfile layer and the error message are shown below. LAYER ...
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1answer
174 views

Nearest neighbour for every row

I'm relatively new to PostGIS and postgresql . I'm trying to build a simple query containing two relations as follows : I've two relations R1 and R2 both of which contains geometries(Points) . I ...
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2k views

How to Calculate length of polyline geometry for several tables in PostGIS?

PostGIS database contains several geometry (polyline) tables (with names "D1_r", "D2_r", "D3_r"). I calculate length for one "postgis layer" use request: SELECT ...
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1answer
1k views

Extract lat, lon Points from Polygon

I have PostGIS database, and want to extract lat, lon pairs sequence from Polygons (and MultiPolygons). As a very fresh PostGIS user, I'm able to just extract the Polygons: SELECT ...
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1answer
508 views

How to split polygons with another polygon and inheritage data?

Let's say that we have two tables with polygons representing areas. Table A and Table B. Geometries from table A represents both the valid and invalid areas. And the geometries in table B represents ...
2
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1answer
927 views

Get the lines between all points of a polygon in PostGis : avoid nested loop?

I am trying to get all the lines between the points of a polygon, by writing PostGreSQL functions. I have written the two following functions that do the job fine : the first function to get all the ...
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2answers
3k views

What Spatial Reference System do I store Google Map's Lat/Lng in

I am new to PostGIS, Spatial Reference Systems and projections and want to store lat/lng coordinates retrieved from Google Maps and Openstreetmap and its services like the Geocoder/Nominatim. I'm ...
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1answer
323 views

Hyperlinking to PostGIS Layers and Zip files with QGIS Actions

I previously asked a question about hyperlinking data in QGIS that gets loaded into QGIS (see post: Hyperlinking in QGIS - Add Data to current window). A user provided me with the code, which works ...
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1answer
626 views

overlay my shapefiles stored in database to the web/browser [duplicate]

I am very much strrugling on how to display my shapefiles stored in postgis database to the browser or to the web.. is there anyone there knows how to do it.? I am using geodjango framework in ...
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1answer
606 views

Polygon to fill gap

Using postgis I want to fill a gap between other polygons. Can you help with some directions what functions to use ? Thank you and sorry if the question is rather noobish. Image to explain from ...
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1k views

Growing a PostGIS geometry by a percentage

I'm looking for a way to add a buffer around a PostGIS geometry, but the size of the buffer should depend on size of the geometry. That is, I want each geometry to be enlargened by, say, 5%. The idea ...
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2k views

getting dxf files out of PostgreSQL

I've successfully loaded a bunch of shapefiles into a PostGIS database. I would like to be able to retrieve specific geometry and layers as dxf files based on SQL queries. I'm using PostGIS, GDAL, ...
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2answers
5k views

PostGIS ST_Buffer Radius Help

I am trying to find all points within a five-mile radius of a given point. I have a query like this: SELECT * FROM table WHERE ST_Contains(ST_Buffer(geomFromText('POINT(0 0)', 4326), ?), latlon) I ...
7
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2answers
663 views

How to replicate ArcGIS Intersect in PostGIS

I'm trying to replicate this ArcGIS process in PostGIS: http://blogs.esri.com/esri/arcgis/2012/11/13/spaghetti_and_meatballs/. This describes how to break buffered points down into polygons based on ...
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1answer
2k views

What is difference between ST_DWithin and ST_Distance for proximity search in PostGIS?

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 ...
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2answers
6k views

PostGIS Geometry Query returns “Error: Operation on mixed SRID geometries” only for certain values

I have PostGIS table with two geometry columns, both defined with SRID 4326. I can insert into the table without problem, using the following INSERT statement (where lng and lat are values passed in ...
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1answer
862 views

Join based on maximum overlap in PostGIS/PostGresQL?

I have two sets of polygons in two tables. The sets overlap each other. For each polygon in set A, I would like to get the ID of the polygon in set B that it overlaps the most. I'm using PostgreSQL ...
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3answers
4k views

When should I use ST_Buffer?

I would like to know what is the sense of using st_buffer operation. In PostGIS reference guide there is only the syntax and a short description of this operation. Could you give some examples to ...
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2answers
1k views

PostGIS - area-weighted calculation on an intersection

I'm trying to learn postgis sql by performing some familiar operations from ArcGIS. Here, I want to perform an area-weighted calculation of certain populations on the intersection of a set of parcels ...
6
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1answer
3k 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 ...
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2answers
4k views

How to add Geoserver WFS to Leaflet JS Application

I have a PostGIS database and have successfully consumed a table into GeoServer and published a WFS. Are there REST endpoints available for these WFS' akin to ESRI's feature services? How are ...
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1answer
277 views

How to transform a set of street-segments into city-blocks, with PostGIS2?

Theoretically is possible to obtain the polygons of city blocks (urban blocks) from streets, when streets are represented by street axis (LineStrings). The urban blocks are bounded by streets, so ...
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3answers
1k views

Adding a GIS feature to existing database entry with QGIS

I've built a database with postgreSQL with tables, which include geometry columns. When I add some data to my non-geometry columns, I can see them in QGIS when I connect to my database using postgis. ...
5
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1answer
990 views

Split edges at intersections in PostGIS

I'm attempting to do a walking distance analysis using OpenStreetMap data (osm2pgrouting) and PostGIS and following underdark's blog posts, however I need to exclude residential and service roads that ...
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3answers
1k views

Convert KML to shapefile without losing attribute data

So I want to convert KML files to SHP shapefiles to load it onto PostGIS. Currently I'm using ogr2ogr to do the conversion for me, but it wipes out all the attribute data. How do i preserve this ...
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1k views

Where to type pgsql2shp command

How to convert post gis database into shapefile, I found that I need to use pgsql2shp command on postgis database query , But how to use it and where to use it. Do I have to use it in the postgre sql ...
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2answers
477 views

Extract PostGIS line features to GPX

I have a request to provide GPX files of certain trails (around 100) that are present in OpenStreetMap. Given a local PostGIS install with OSM data, I think the process would be something like: ...
3
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1answer
497 views

ST_Equals Postgis problems

I am trying to find overlapping lines using ST_EQUALS on two tables This query returns 0 rows: SELECT * FROM geom1 c, geom2 h WHERE st_equals(c.simple_geom, h.simple_geom); This query runs ...
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2answers
1k views

How to debug 'Layer is not valid error' from Python plugin?

I'm trying to understand what goes wrong with a QGIS python plugin. Basically I'm trying to render a series of POINT. The query works fine, at least giving it by hand from inside PostGIS DB: "SELECT ...
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2answers
253 views

How to create more networking osm

Using localhost page generated by osm2po roteamente noticed that the link is made to link even disabling snapping. Logically thought to create more nodes in the network, but how can I do this ...
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1answer
1k views

How to split line layer at polygons' boundary of a polygon layer?

I have a line layer and a polygon layer in PostgreSQL 9.2, PostGIS 2.0. How can I split every line each time it crosses a polygon's boundary?
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3k views

Why does ST_Transform fail?

I got a postGIS error like this, ERROR: transform: couldn't project point (100.496 13.7118 0): latitude or longitude exceeded limits (-14) SELECT ...
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128 views

create automatically temperature or isotherms map with PostGIS?

Is there any possibility to create automatically temperature or isotherms map through a points table stored in PostGIS? I need to serve this map on a web (Geoserver). The information is updated each ...
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411 views

Help defining custom CRS in QGIS 2.2

I'm trying to use EPSG:4479 in QGIS. 1) If I search for EPSG:4479, it returns a "Imported from GDAL" EPSG:4479, but it does not work. At the console, the following message is displayed: ERROR 6: ...
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1answer
553 views

Automatic bulk snapping with FOSS

I'm looking for a tool that would be able to automatically snap features closer than a given distance. Is there such a tool/plugin for QGIS/GRASS/OpenJump? Would it be possible to achieve that with ...
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580 views

In what situations would SpatiaLite be selected over PostGIS, and vice versa?

I know that SpatiaLite is a lightweight solution. Would it be a problem if I put it on a 5K pageview/day site? Is PostGIS too resources-consuming for such usage? The dataset is something like < ...
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3answers
688 views

Import shapefiles on my postgis table using R

Using R, I would like to import shapefiles that are in a directory on a geometric table i have on postgresql / postgis. What is the instruction that allows me to do it? EDIT: here is my code to ...
7
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1answer
1k views

How is ST_PointOnSurface calculated?

The PostGIS documentation states that ST_PointOnSurface returns "a POINT guaranteed to lie on the surface". It seems like this function could be trivially implemented to give results that satisfy the ...
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3answers
2k views

Best choice for building static maps: PostGIS, SpatiaLite or Shapefile?

I usually build static topographic maps, which are mostly printed. I'm often using OSM and rasterfiles (mainly different DEMs). The areas I'm mapping seldom exceeds 20.000 km². I'm using exclusively ...
5
votes
1answer
711 views

How to interpolate polyline or line from points?

We have a lot of points, but with no timestamps to create ways. For now, I've created a sample of the way the points traverse. It's in here, this way can be compared with a Google one. I haven't ...
5
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1answer
391 views

Calculating path sinuosity in postgis

Sinuosity is a fairly straightforward concept. How can this be calculated in postgis given a series of linestrings that represent the path?
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1answer
741 views

Visualising a raster PostgreSQL table in QGIS

I have imported a raster tif image into PostgreSQL with this command: raster2pgsql -s 32643 -I -M filepath.tif -F -t 100x100 public.databassename > filepath.sql And imported the output SQL file ...
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2answers
1k views

SQL Syntax to extract (convert) Strings with Degrees Minutes to Decimal Degrees

I have a PostgreSQL/PostGIS database with a two string fields containing Lat and Long coordinates in degrees and decimal minutes, like this 45° 24.5' N 3° 43.01' E. How can I convert them into ...
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0answers
720 views

How can I properly add PostGIS data into MapGuide Maestro?

I am having trouble connecting a PostGIS database to MapGuide Maestro. Actually, I have added the PostGIS data into Maestro, but when I click to validate the layer it shows an error message: ...
4
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1answer
7k views

How to filter features in a layer?

I am trying to display certain features in a shapefile-based layer using QGIS. I have found the subset function in the properties panel, which does exactly what i want, but is too tedious given that I ...
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3answers
558 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 ...
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2answers
504 views

How to enable SFCGAL in PostGIS?

I have the problem with the enabling extension SFCGAL. CREATE EXTENSION postgis_sfcgal; doesn't work for me even I have the PostGIS v2.2. When I do that, it throws an error ERROR: could not ...
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1answer
131 views

Create common vertexes between shared polygon boundaries in PostGis?

Given two polygon tables L1 (blue) and L2 (red) that share a common boundary but different amount of vertexes, how can one make the shared boundary identical (they should share the same vertexes) ? ...
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636 views

Editing PostGIS data in ArcGIS Desktop?

Quick question regarding editing PostGIS data in ArcMap 10.0. Far as I can tell, this can only be accomplished through third-party plugins like GISSquirrel or ST-Links. Does anyone know of an ...