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

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Split lines into non-overlapping subsets based on points

Given a table with line geometry, and one or more points that are snapped to this line in a separate table, I would like to split each line with one or more intersecting points at each of the ...
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Calculate distance of point from an arc/polyline

Using Postgres/PostGIS, I am trying to query the database for the closest arc to a particular GPS point. Each Arc is made up of two nodes that are GPS points on a map. Is there a way I could query ...
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728 views

postgis, extrapolate a line

I'm trying to extrapolate from a line segment to find a point on the line but a 3rd of the way 'back', i.e. trying to find point new, given points A and B below: Given a line, I can interpolate it ...
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How to estimate the average width of a sidewalk? [duplicate]

I have a table with two polygons representing urban block with and without the sidewalk: geomBlock and geomBlockWithSidewalk. On my city we can approximate the polygons of geomBlockWithSidewalk to a ...
7
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1answer
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How to import GeoTIFF via postGIS into GeoServer?

As a simple test case, I'm trying to configure the software stack of OpenGeo such that I can display a GeoTIFF as an overlay to a normal map like OSM. So I perform the following steps: Create a ...
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How to connect OpenLayers to PostGIS data?

I have read in OpenLayers how to load KML, GeoJSON etc. vector files in OpenLayers. But how can I connect to PostGIS data. If not, why should I upload my data to PostGIS then instead of directly ...
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How to display a PostGIS table on Google maps?

I am attempting to take a shape file and display it on a map: I can do something like this: SELECT ST_AsText((ST_Dump(the_geom)).geom) as the_geom FROM shapes; But the problem is I still have to ...
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How to assign geometry to records in a table that contain an ID of a geometry point?

We are looking to map out 'incidents' at schools, but the incident table, which contains a few thousand records, only has a school number (plus the incident data). The table format is an Excel ...
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How to find nearest line from point using PostGIS?

I have a table of Roads in PostGIS which geometry is "geometry(MultiLineString,4326)". Its attribute are gid osm_id name ref type oneway bridge maxspeed geom Now i want to know ...
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How to convert PostGIS table to Shapefile in Python?

I want to convert a PostGIS table into a shapefile (without using pgsql2shp). In order to create a geometry in the shapefile I have to give the Xmin,Ymin and Xmax,Ymax, and the geometry which I have ...
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Separating Overlapping DMAs by State using PostGIS?

I have two shapefiles. One is the DMA and another of states I know that some DMAs, such as Chicago will overlap between multiple states, for instance the Denver DMA overlaps states outside of CO and ...
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1answer
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How to verify a PostGIS installation on OS X?

I am trying to set up GeoDjango and installing PostGIS on my mac and when I am trying to ./configure I am getting this error checking PostgreSQL version... PostgreSQL 8.4.9 checking libpq-fe.h ...
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8answers
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How to create Vector Polygons at the same amazing speeds GISCloud is able to render them?

EDIT (outlining new bounty added): I have added the largest bounty possible to this question in hope of getting a very detailed answer. Your solution should outline a step-by-step guide utilizing open ...
14
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5answers
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Find pseudo nodes in free GIS software

Software gvSIG OA Digital Edition 2010 have tools topology for finding pseudo nodes in linear geometry. I set cluster tolerance 0.00002 and maximum number of errors -10000 for 20000 link count linear ...
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5answers
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Working with PostGIS data in R?

I work with R almost all the time, and now I am using it for doing spatial data mining. I have a PostGIS database with (obviously) GIS data. If I want to make statistical spatial analysis and plot ...
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2answers
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In PostGIS is it possible to create a View with a unique ID?

When I create a view in PostGIS is there any way to add a unique ID to that view? Just like the "gid" field in any other PostGIS table? Edit: Sorry I should have included this in the original post. I ...
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How can I merge/collapse nearby and parallel road lines (eg. a dual-carriageway) into one single line?

I have a shapefile from OSM which contains all the roads within a city. Larger roads (like dual-carriageways) seem to have 2 parallel lines. I'd like to collapse / combine those into 1 line so I can ...
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2answers
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How do you display related records in QGIS?

Coming from an esri background I have always used relationship classes in a gdb to display records related to a feature. Eg. Relate 1 survey point to many documents, photos etc. Does any one know how ...
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What in-depth spatial database systems tutorials exist?

Is there a good tutorial that explains in depth the internals of a GIS and a spatial database system such as PostGIS with examples and without any background assumption? I'm specifically looking for ...
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3answers
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Identifying road intersections using PostGIS

I'm trying to identify where roads intersect each other, and to make a point at this intersection, with the number of roads that form the intersection listed. I was wondering if there was some way ...
5
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2answers
1k views

How to perform SIA or Bezier line smoothing in PostGIS?

Can anyone provide an example SQL for smoothing linestrings from postgis table using Bezier curves or Iterative Averaging (SIA) algorithm?
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1answer
908 views

How to render a table with mixed geometry types in QGIS?

I created a table with geometry type "GEOMETRY" AND inserted data of point, line and polygon type. My question is how to show this spatial data Qgis not supporting for geometry type "GEOMETRY".
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Search functionality in Openlayers/Geoserver

I am using Openlayers,Geoserver & Postgis.... My postgis tables are having columns as id, name, POINT/POLYGON/LINE. Each table corresponds to a layer that I am showing in layerswitcher in OL. I ...
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2answers
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How to get multiple shortest paths with PgRouting in one query?

I want to run shortest path algorithm on multiple source&target pairs at once and get a result as a table and process it then. How do I do this? This query does not work: SELECT a.source, ...
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3answers
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How to create spider diagrams (hub lines) in PostGIS?

I'm rather new to PostGIS but I have done a lot of reading. One thing that I have been searching for is a function that allows users to create a "spider diagram" (also called "desire lines" or "hub ...
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How to import a raster into PostGIS?

I'm trying to follow the instructions here to load a raster into a PostGIS database: python raster2pgsql.py -s 4269 -I -r *.tif -F myschema.demelevation -o elev.sql I understand that I replace * ...
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1answer
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How do I get a route between two points using PgRouting with TIGER2010 Data

A little background: I've got PostGIS 2.0 and all the TIGER2010 data loaded for a U.S. State California. I've got a table with points stored as data type geometry. I've learned enough to get the ...
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2answers
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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 interpolate GPS Positions in PostGIS

I have a PostGIS table of GPS positions for every five seconds: 2011-01-01 00:00:05, POINT(x1,y1) 2011-01-01 00:00:10, POINT(x2,y2) 2011-01-01 00:00:15, POINT(x3,y3) ... I'm looking for a query ...
10
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1answer
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Merge Multiple Tables into a New Table in PostGIS

I am looking to merge a number of individual tables into a new table in PostGIS. This is an easy task when working with Shapefile data, but I am unsure how to do this in PostGIS. Any help would be ...
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How to convert MultiLinestring to Linestring?

I have a multiline string and want to convert it to a linestring in order to use some functions that only work with linestrings. I used ST_Dump() and got a collection of my geometries. If I merge them ...
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How to connect points (bus stops), which don't lie on the lines (LINESTRING), to a network?

I need to connect bus stops (points) to a network layer (OSM data). These bus stops do not lie directly on the lines (see screenshot) nor should their location be moved. I use PostGIS, pgrouting and ...
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2answers
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I want to edit corresponding postgresql data of a vector from openlayers- how to do it?

I want to edit the corresponding text/numeric data type columns of a vector through openlayres, when a user click/mouse over a vector. like, http://dev4.mapgears.com/bdga/bdgaWFS-T.html# any ...
3
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4answers
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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: ...
3
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2answers
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How to install PostgreSQL 9.2 with PostGIS 2.0 on Ubuntu 11.10 (or higher)?

I have read this question: Install PostGIS v2 for PostgreSQL v9.2, but it didn't resolve my problem. I added the PostgreSQL backports PPA and installed the postgresql-9.2 package, but there is no ...
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1answer
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qgis to local postgis connection - fails

It seems pretty clear I cannot connect to a local postgresql installation out of QGIS. This is my first experience with PostGIS. I am using PostgreSQL 9.0 on a win7 machine. I can see the successful ...
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2answers
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What is this PostGIS query doing to show great circle connections?

I'm trying to draw a flight map in CartoDB. My starting point is a single lat long point. We'll pretend it is this: ST_GeomFromText('POINT(-71.060316 48.432044)', 4326) And I want draw lines ...
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2answers
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Connect to postgres localhost in QGIS

I am firly new to actively work with databases. I wanted to try out some stuff on my home computer where I have installed pgadmin and postgres previously. I can connect to my localhost in pgadmin but ...
2
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1answer
788 views

Get a single cluster from cloud of points with specified maximum diameter in postgis

I have on the order of 2M Geometry Collections with N (median: 2, stddev: 6.6, 75th: 6, 95th: 21) Point objects (repeated points allowed and important) in a PostGIS table. I want to identify clusters ...
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2answers
559 views

take from multilinestring the start & end points

I have to use the A* algorithm and my geometry is in multilinestring and i want to take stratpoint(x1,y1) and endpoint(x2,y2) . I use this queries but the colums after the execute is still empty ...
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2answers
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How to select all points within a circle in PostGIS?

I have set of points in a PostGIS Table (Type Geometry). Now, I need to filter points that lie in a circle with a center (C) and radius (R)! I expect C to be of type Point or Coordinates.. R to be ...
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1answer
856 views

psycopg2 error with QGIS 1.5

So I just installed QGIS 1.5 using the windows installer not the osgeo4w one and now any plugins that need access to PostgreSQL databases don't seem to work, they all throw a: "Couldn't import Python ...
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1answer
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How to perform a spatial join of point and polygon layers in PostGIS?

I have a point dataset representing households that I want to associate with a parcel layer (i.e. assign its parcel_id). With ArcMap, I could spatially join the polygons to the points and specify that ...
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Clarification of the “25D” option in ogr2ogr

[EDIT: In my original post, I had received an error that was based on a typo, so I scrapped that part of the question, but left the questions that still apply.] In the ogr2ogr docs it says: -nlt ...
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1answer
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How to Import ESRI Geodatabase format .gdb into PostGIS

I ran into a problem when loading a ESRI Geodatabase format .gdb into PostGIS. I have data 2.5GB GDB file. I followed some tutorials on the internet, but it seems that doesn't work out. I created a ...
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1answer
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Install PostGIS on Ubuntu 12.04

I am trying to install PostGIS on Ubuntu 12.04 and I think everything is installed correctly except for postgresql. I followed this post. I get the following error and nothing I do seems to satisfy ...
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2answers
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QGIS DB manager Import layer/file tool won't allow me to choose “Append data to table”

I want to append some data to a layer in my PostGIS DB using a shapefile, but when I use the Import layer/file tool in QGIS, it doesn't allow me to choose the append option. Why is this and how do I ...
3
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2answers
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How do I use st_dwithin with meters?

I am trying to follow PostGIS ST_Buffer Radius Help to use a 50 meter distance but postgis is returning an error. I am trying the following SQL, SELECT id FROM table WHERE ...
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1answer
272 views

pgrouting unexpected output

Thats my ways.shp file. I loaded this to PostgreSQL DB using PostGIS shape file loader. I ran pgr_anlayzeGraph() on it and found it had a lot of isolated segments. Next I ran pgr_nodeNetwork() to ...
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ST_DWithin uses Geometry or Geography type

assuming I use the following query to match the locations to a poi within 10km distance: SELECT poi.poi_id, h.loc_id, (ST_Distance(poi.geom,h.geom)*111.111) as distanceinkm FROM iut_poi_transl AS ...