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

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Queries returning very big datasets in PostGIS

I have a PostGIS query that will return several million rows: SELECT t1.id AS id1, t2.id AS id2, ABS(t1.mean_h - t2.mean_h) AS h_diff, ST_Distance(t1.the_geom, t2.the_geom) AS dist FROM ...
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Output polygon data from postGIS and read it on Google Maps API

So, I have a group of polygons stored in PostGIS. I'm trying to build a web application with Google Base maps (using Google Maps API). Now, How do i output the polygons in the right format so that ...
7
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781 views

PostGIS Intersection and Summarise Attributes

I am usually an ArcGIS desktop user, but keen to start using PostGIS more and I have a really big bit of processing to do. Not sure what functions to use, hopefully someone can help. I have a polygon ...
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1answer
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gdalwarp, cutline and postgis

I can not figure out how I directly can read a polygon into gdawarp's -cutline argument. My current approach is: ogr2ogr -f "ESRI Shapefile" mydata.shp PG:"user=myuser dbname=gisdb" -sql "select * ...
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481 views

How to check if points are within a circular sector using PostGIS?

I want to get the stars within the black region as shown above. To find this I have the centre of circle (lat, long), radius and the angle of region (45 degree). I am new to postgres. I worked on ...
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Join intersecting lines with PostGIS

This is something that I'm almost ashamed to ask but I can't seem to get it to work for the life of me. I have a road layer with segments, each segment has a Road ID and a segment type. I would like ...
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ST_Intersection slow query

I am trying to perform an intersection between two layers: Polyline layer representing some roads (~5500 rows) Polygon layer representing irregularly shaped buffers around various points of interest ...
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879 views

How to create a routable road network from Ordnance Survey data?

I've been following the "Beginners Guide to pgRouting" in an attempt to create an in-house application that provides drive-time isochrones. I have a server, postgreSQL and PostGIS and pgRouting - no ...
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Install PostGIS and TIGER Data in Ubuntu 12.04

Could someone write a brief albeit dumbed down idiot's guide to installing postgis and loading national Tiger data on ubuntu? I've tried a few guides, namely, ...
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How to create a new 'gis' database in PostGIS?

I'd like to create a new database in PostGIS, so I can load stuff into it while the current database is being used. According to the docs Some packaged distributions of PostGIS (in particular the ...
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4answers
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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 ...
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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 ...
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How can I calculate the bearing between two points in PostGIS?

How can I find the bearing between two points in PostGIS? Please specify in your answer whether or not the method producing a bearing on the spheroid, or a planar bearing.
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How best to fix a non-noded intersection problem in PostGIS?

I'm using a PL/R function and PostGIS to generate voronoi polygons around a set of points. The function that I am using is defined here. When I use this function on a particular dataset I get the ...
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3answers
659 views

How to add offsets to the route?

Edited: I want to ilustrate my question. Suppose that you're in "Point A" and want to go to "Point B". This points wouldn't be in "at_2po_4pgr" table cause aren't source/targets nodes. Then, I ...
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Web mapping software for a huge raster time series?

I'm an ArcGIS Desktop user who is stepping into the world of web mapping for the first time. Following advice I found here on GIS.SE, I started with the free tutorials from OpenGeo. However, I ...
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How to import esri Personal Geodatabase (.mdb) to PostGIS on Linux

We have esri Personal Geodatabases that we need to import into PostGIS. Ultimately, we'd like to allow people to upload an MDB on a web server, and have it import the layers into PostGIS. On ...
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378 views

What is the best hack for importing large datasets into PostGIS?

I have to import large Shapefiles (> 1 million records) into PostGIS, and I have been wondering about the best way to do it. In my question I used the word "hack", instead of tool, on purpose ...
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Database versus Files for Solo Developer

I'm just getting started in GIS and am interested in using it to create maps of mountain biking trails in my area and nearby. I've been learning QGIS and have made enough progress to generate a decent ...
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Storing GML surface in PostGIS

I'm using PostGIS 2.0.0 and would like to store a GML Surface in a way that allows calculating intersections between that surface and various points and lines. In my case, the Surface will have one ...
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1answer
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How to import KML file, with custom data, to Postgres/PostGIS database?

By custom, I don't mean a different structure of KML file, but in <description></description> section, I have data with HTML tags of this kind: <?xml version="1.0" ...
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1answer
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PostGIS 3D in Action

I was wondering if there is a website that showcases Openlayers and PostGIS 3D in Action
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memory issue when trying to buffer/union large dataset using postgis

I am trying to generated a dissolved buffer of a large point dataset (Ideally 29 million points - Address data in Great-Britain, but I receive the data by chunks of 1 million points, so these could be ...
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179 views

How to install a patch in PostGIS

Can anybody tell me how to install this patch in PostGIS? http://trac.osgeo.org/postgis/ticket/413 http://trac.osgeo.org/postgis/changeset/7534 I need to use the ST_OffsetCurve function. but it ...
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How to locate PostGIS AMIs on Amazon EC2?

There are nearly 7000 AMIs on EC2, but I'm having a difficult time figuring out which ones have what I'm looking for--in this case PostGIS on Linux. No specific version/configuation--I want to check ...
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How to route over (partial) edges in pgrouting?

I have made a route planning system (based on shortest path using A*) like the Google directions service using pgrouting and google maps. It includes clicking on the map to generate waypoints, ...
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How to add a polygon from PostGIS ST_AsGeoJSON into Leaflet?

I try to use the following function to add polygons to my Leaflet map. function polygon(geojson) { alert(geojson); // alert for testing layer = L.geoJson(geojson); layer.addTo(map); } ...
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2answers
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Automating batch load of multiple GPX files into PostGIS

I've got 50+ GPX files that I would like to "batch load" into a PostGIS database. All of the track_points data would be loaded into a "track_points" table (with typical GPS fields like lat, long, ...
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4answers
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GeoServer Layer from PostGIS not updating

I created a WMS layer from a PostGIS table with a fraction of total polygons in GeoServer. Everything displayed fine. Then, I added the rest of the polygons to the table in postgis. For some reason ...
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Writing a plugin for Qgis using python to access PostGIS and write geometries

Sorry about the strange title didn't really know how to word it. I currently use MapInfo to do most of my GIS work however I have recently installed PostGIS 1.5 and am really liking it so far. A ...
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1answer
387 views

How to query OSM for all beaches facing west? - QGIS preferred

I want to identify all beaches on this planet (or a given subset of it) that are facing westwards (+/- 20-30 degrees). My idea is to use OSM as the data source. Extracting all polygons that have the ...
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How to use ST_Intersection?

Here's a quick summary about what I'm trying to do: I have 3 tables in Postgres, 'a' and 'b', each have a Polygon column, and 'c' has a Point column. What I'm trying to do here is to get the ...
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PostGIS: Assign ID of point in layer A to closest point in Layer B

This should have been an obvious precursor (that I didn't ask) to my other question: PostGIS function to create spider diagrams? If I do not know the relationship between a point in layer A (stores) ...
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2answers
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Are there any tricks to using a schema other than public in PostGIS?

I'm currently setting up a fresh install of PostGIS 2.0.2 and PostgreSQL 9.1.6 on Ubuntu. I've recently come across some information indicating that using the public schema to store all data is not a ...
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How to Export Feature GeoJSON from PostGIS

I'd like to do a GeoJSON dump of a PostGIS table, but I want to export features (the geometry and the properties) not just the geometry. I've been digging into the ST_AsGeoJSON function but it looks ...
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Finding the closest Geometry in PostGIS

I've been looking over the PostGIS "API" of functions, and I notice that most of them take two elements to compare. For example, the ST_Distance function takes two geometry/geography elements to find ...
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3answers
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How to install PostGIS on Windows?

I want to create an application platform based on PostGIS data. I read the documentation where I saw the prerequisite to install GEOS, GDAL and Proj4. The main problem is I am using windows platform. ...
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How to add features to a PostGIS layer using Quantum GIS?

I am using Quantum GIS and the PostGIS dbms. I am able to call the PostGIS layer into QGIS but i am unable to add feature to it. I am using the method of adding features to a Shapefile but still it is ...
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Beginner PostGIS question: getting geometry from multiple tables

I am very new to PostGIS, PostgreSQL, and SQL in general. I have 44 tables in my PostGIS database, and each one represents a different layer of vector data. Each was loaded from a separate shapefile, ...
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2answers
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How to add vertices to existing linestrings?

If I have Linestring(1 2, 1 5, 1 9) and a Point(1 3) Is there any function that can merge linestring and point preserving the order so output would be: Linestring(1 2, 1 3, 1 5, 1 9)
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1answer
699 views

How to Simplify a Line Network Preserving Topology?

I have a Shapefile (consisting of European major roads) with about 250.000 Segments which I have to simplify for pgrouting. But I can't seem to find a way to do that properly. This is what it looks ...
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How to preserve topology while editing polygons in OpenLayers?

I’m facing this issue: I have a chloropleth map based on a set of polygons with some data. Using WFS-T (postgis, geoserver, openlayers) I am able to edit the geometry of the polygons. This works fine. ...
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2answers
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Find headwater polygons

This is a follow up question to this question. I have a river network (multiline) and some drainage polygons (see picture below). My goal is to select only the headwater polygons (green). With ...
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2answers
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PostGIS Union Between Two Tables, Preserving Attributes

I'm trying to union US State level upper- and lower-level government boundaries in such a way that generates one PostGIS table with both the upper and lower level names for each shape. In my example ...
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1answer
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Why do simplify polygon results differ between ArcGIS for Desktop and PostGIS?

I am mainly interested in why and how the Simplify Polygons tool in ArcGIS for Desktop handles the simplification process, including preventing and resolving topological errors better than the ...
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How to run two PostGIS versions in parallel on Windows?

I'm trying to understand how to install PostGIS2.0 on Windows7. The PostGIS site has the following suggestions: PostGIS Experimental Binaries PostGIS 2.0.0SVN Binaries with Raster, Topology ...
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Are there open source solutions for travel demand modelling?

I'm looking for open source tools for travel demand modelling (eg The four-step UTMS). Preferably in a GIS environment. That works well with Qgis, Grass and Postgis. My question is not related to ...
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Storing GPS tracks with timestamps in PostGIS

I need to store a series of GPS points with timestamps in the database (traces of various vehicles). I am wondering which of two approaches to choose for storing them in the PostGIS table: 1.) Each ...
6
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1answer
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Performance Gain Through GIST Index for Point in Polygon Query

I have two tables: locations(id,region_id,the_geom) and regions(id,the_geom). For each location point I want to determine the region it is located in: UPDATE locations SET region_id = (SELECT id ...
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How to measure length of line accurately?

In postgis 1.5 for the below given query the answer is 1540651.62674101 meters , SELECT ST_Length(ST_GeomFromText('LINESTRING(77.83042478941326 9.98463896136159,78.03469506809812 23.90398909552571 ...