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

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Identifying topological relationships using PostGIS

I'm trying to perform a basic typology analysis using PostGIS. My objective is to find any polygons that touch other polygons. To do this, I thought the ST_GetFaceEdges would work (reference). I want ...
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How to create PostGIS template?

I am following a tutorial to install pgrouting. However, I didn't get the part when it says Start pgAdmin and create a new database based on your PostGIS template Where can I get this postgis ...
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Spatially enabled Postgres database

I am trying to create a spatially enabled PostGIS database. I am following the PostGIS documentation, http://postgis.net/docs/manual-1.5/ch02.html#id2648455. In the short version, i executed, ...
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How can I transform polylines into points every n metres in PostGIS?

Question in pretty much the same as this, but I need to use PostGIS. I have a number of polylines, and want to trasform them into points every n metres along these lines. edit: Thanks a lot to ...
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What is the best web editor and server for postgis?

I'm looking for a web editor (similar to openstreetmap) that works with an map Server (postGIS). This should permit edit and create new structures on map. What is the best option? Can you help me? ...
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How to implement Spatial Autocorrelation using QGIS or PostgreSQL (or any free application)?

I am a total newbie on the GIS scene so I hope this is not a stupid question. I have two layers in a PostgreSQL database. The first layer contains points where events happened in Europe. The second ...
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Moving a PostGIS Installation

I have a simple question: I have a postGIS installation running on an old computer that I'd like to move. I spent a bunch of time playing with pg_dump and pg_dumpall without success. It seems the ...
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PgRouting - How to clip links when reaching max costs?

I have a polyline shapefile representing a road network and a second shapefile containing points. I would like to use PostGIS (presumably PgRouting) to identify sub-networks or service areas radiating ...
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Nearest Neighbor Grouped Selection in QGIS

OK - so I have an interesting problem I am trying to solve. I have a list containing over 100,000 points in lat/long format which I have imported into qgis. Now, what I am trying to do here is group ...
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Version editing for Postgresql 9.2.4 / postGIS 2

Background: I am "building" a GIS with PostgreSQL 9.2.4 / PostGIS 2 as the database and QGIS 1.8.0 as the geographic application. There will be multiple users accessing, editing and viewing the data ...
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Editing PostGIS/GeoServer data via web?

I've got PostGIS installed and would like to create a web application to do some simple edits: Draw manually (over a Basemap) points, lines and polylines, using snapping points (points, end of ...
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Is there a CASE Tool for modelling spatial databases?

Does anyone knows if there is a CASE Tool that would be possible for modelling spatial tables? I need to create a model and export it to SQL or a database directly. I´m using PostGIS. Thanks in ...
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Visualization of 3D shapefiles with Mapserver and Postgis

I'm wondering is there a way to visualize 3d data with mapserver? 3D .shp files are in postgis database, and I already connected mapserver to database, but with simple layer in mapfile.
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How to identify and simplify point clusters with regard to time in PostGIS?

I just started to work with spatial databases and I want to write a SQL(PostGIS) query for automatic generalizing of raw GPS-tracks (with fixed tracking frequency). The first thing I am wokring on is ...
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Should I use a CMS for my web mapping application?

For my web mapping app, I am using GeoServer as server, PostGIS as spatial DB and OpenLayers on client side (as well as other JS libraries). The map is composed of base maps and vector layers. One of ...
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What is the best way to do reverse geocoding with PostGIS?

Is there a way to do reverse geocoding with PostGIS? There's a lot of information on the Web but I found it very confusing... I have imported osm data into my own Postgres with PostGIS database. Now ...
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PostGIS Intermittent INDEX Performance

I have a table containing approximately 55 million data points ( point is a geometry with SRID 4326 ) and for my query I need to join this to an area table ( currently have ~1800 areas ) which ...
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How to merge close points into polygon?

I have a set of coordinates (points & no overlaps) in a single table,each containing attribute number fields,like in the following image. I want to merge these points into smallest polygons by ...
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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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How to find the nearest point projected on the road network?

I would like to know if there is a function at pgRouting that given a point (lon/lat) can give you the projection of that point to the road network . Thanks in advance john
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What are hardware requirements for a cloud hosted PostGIS & GeoServer?

I have been playing with a local installation of PostGIS & GeoServer. I would like to move my work online now to share it with several collaborators. The proof of the concept map will consist of ...
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PostGIS interpolation / triangulation options

I'm looking for an open source workflow to automate DEM construction. We have a series of sites that fall within a LIDAR dataset. We want to create site specific DEM's for each site, and we're ...
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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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Are there Desktop GIS alternatives to ArcGIS 10.X for topology and vector conflation?

Is there any options other than ArcGIS for Desktop for topological rules and automatic topology integrity enforcing in a Desktop GIS? I am looking for something that will automatically snap features ...
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How to populate an undirected graph from PostGIS?

This question is more related to resources that I might not have identified yet, although I've been searching the web for a while. In the project I'm working at the moment I need to run a ...
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Is it possible to geocode street intersections using Nominatim?

Is it possible to geocode the location of a street intersection using Nominatim? Example geocode query Commonwealth Ave at Washington Street, Boston, MA Successful Geocode by Google ...
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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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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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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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796 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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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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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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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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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 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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In Qgis, Is it possible to edit the datasource of a Postgis layer?

After creating a layer with RT_SQL_Layer plugin, I want to change some details in the query. Is it possible? or I have to aways create a new layer every time I want to change something in the query? ...
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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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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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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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4answers
713 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 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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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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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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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 ...