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

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PostGIS Dissolve/Union close polygons

I have approximately 1 million polygons that have been split by lines. However, this has caused one half of a polygon to be separated by approximately 50cm from its other half. After doing a lot of ...
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107 views

Why does only one of the following queries throw an error?

There are 2 SQL queries: SELECT wkb_geometry FROM building_polygon WHERE ST_Contains(wkb_geometry, ST_GeomFromText('POINT (29.4 60.1)')); SELECT wkb_geometry FROM building_polygon WHERE ...
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663 views

How to find out what features /tags are included in an .osm or .pbf file?

I would like to load osm data into a postgis (postgresql) database. In How to load OSM data into PostGIS preserving all Tags? there has been a solution posted: Download the OSM files (in .osm ...
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How to select segment of linestring using PostGIS?

i have PostgreSQL+PostGIS. I have a linestring: "LINESTRING(60.7014631515719 56.8441322356241,60.7023117507097 56.8445673405349,60.702948200063 56.8447993944193,60.703902874093 ...
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242 views

Update PostGIS after updating GDAL?

I am using PostGIS 2.0 and I want to use the raster functionality through mapserver. It seems as if the latest official GDAL release 1.9.1 has an unstable PostGIS raster driver, as pointed out in a ...
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How to save a newly created shapefile in PostGIS?

I am creating shapefile using shapefile.py and my database has records more that 65k which is the limit of the shapefile. How can I create shapefiles then? Is it possible that somehow I am able to ...
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392 views

Self-intersecting polygon using extreme values

I have this polygon POLYGON((1.2E-15 1.1E-15,1.31E-15 1.21E-15,-180 -90,180 90,1.2E-15 1.1E-15)) It uses an extreme coordinates like (1.2E-15 1.1E-15) and (180 90) When I call ST_isValidReason, ...
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Performing Geoprocessing SQL Queries in QGIS from a PostGIS Database

This may be a dumb question, but is there way to run a PostGIS geoprocessing SQL query in QGIS? Specifically, I am thinking of running SQLs such as ST_Union, ST_Split etc etc. I have tried the ...
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798 views

Indian Latitude Longitude values

I am in need of around 10000 and odd Indian latitude and longitude values for my openlayers project. I have to load them in a postgis db. so a sql file or atleast text file would be better than a ...
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87 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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125 views

Confused about ST_DWithin function postgis

First Time here. Anyway, I have a database that I want to use to store user locations. I want to be able to get all the users with in say 15 miles. How do I do this. I'm using PostGIS 2.1. My SQL ...
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101 views

Which one of these azimuth values is the right one? And why?

First of all, let's make clear that I want the Azimuth on the surface of the Earth, i.e. the angle between two locations, for example New York and Moscow. I am testing some azimuth calculations with ...
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2answers
401 views

ESRI projection to SRID?

I am looking at MapX and MapY coordinates. The docs say they are "truncated State Plane coordinates: NAD 1983 State Plane Louisiana South FIPS 1702 (US Feet)." I am trying to reproject into a common ...
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433 views

How can I GROUP BY linear spatial clusters with PostGIS?

I have a series of points in a horizontal line, arranged into discrete spatial clusters by the underlying data pattern. Here's an example of what they look like: How can I use PostGIS to group them ...
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Installing postgis on postgresql 9.1 not working

I'm trying to install Postgis 2.0 on a perfectly functionig postgresql 9.1.10 database. I installed the package via: richard@srv1:/$ sudo apt-get install postgresql-9.1-postgis postgis Reading ...
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752 views

Importing grib, grib2, netcdf to PostGIS

According to grib2 to raster? (grib2 -> raster2pgsql -> PostGIS 2.0 -> GeoServer), it seems like that grib2 can be treated as raster directly. Is it the so called "standard" way? How about ...
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846 views

Create a point x meters from origin using st_translate in postgis

How do I create a point 1000 meters away from a reference point? The ST_Translate only supports geometry type. I also tried using ST_GeomFromText but that returns a unit and not in meters. Here is ...
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How to find polygons inside polygon with PostGIS 2.0

I have a relation representing all the counties in my country and the other one containing all the districts - e. g. each and every county is composed of several districts. How do I select them with ...
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396 views

small difference in projection between tilemill and postgis

I would like to create a world map with interaction on continents created directly from a postgis database. For the moment, I have a POSTgis database with the data. I created a background with ...
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2answers
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Select Duplicate Points PostGIS

I have a table made of merged point datasets in PostGIS. I want to select all of the features where two or more points have identical geom values. At present I just want to select so I can review ...
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5k 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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How to get the coordinate system from a PostGIS database?

My question is probably amazinlgy stupid, but I can't find the answer myself. I would like to extract from a database the latitude and longitude of points. For now, I'm getting x(the_geom) and ...
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990 views

Postgis: Is there a way to do an intersection query based on lines while taking into account the dateline?

This is an exact copy of a question I asked on Stackoverflow a few weeks back and still haven't found a good answer for it. The original question is from here: original question. I've been searching ...
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1answer
227 views

PostgreSQL default values in QGIS 2.8.1

I have a problem with default values the are set in a PostgreSQL table. When I work on them in QGIS 2.8.1 and I save the layer, the default values were not computed, so the constraints block me. With ...
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332 views

postgis: cluster/group points based on distance

We have a set of thousands of points and want to group all of those which are within 100m distance from each other (to get the centroid from each group). A first idea was to build 100m buffers around ...
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70 views

Coloring multilinestringzm M values in QGIS

I have output from a geophysical technique that produces X,Y,Z and scalar value for millions of points, which have been stitched together appropriately (by networkx if it matters) into ...
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78 views

Geoserver : create a rasterized polygon / dynamic fill for polygons with features from database

I decided to post here because I couldn't find any answer to my problems on the internet. So I am using geoserver 2.7-SNAPSHOT, everything is working fine but I need to implement a new function or ...
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1answer
100 views

PostGIS GML round trip confusion

I've investigated the issue of coordinate order in GML and each time I think I've got it but I find my self confused once again. I think some of my confusion may be to do with PostGIS. Doing a ...
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1answer
86 views

QGIS select reversed geometries

I have a road network and a geometry for each road direction. One Geometry from A->B and another Geometry from B->A. This geometries are covering each other. Is there a tool available in QGIS to ...
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81 views

Rebuilding a Polygon from the points within it, in PostGIS

This question is an update on the problem formulated here. I wanted to redefine the border of a set of polygons, in order to "smooth it". My first approach (described in the former question) was to ...
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77 views

Redefining the border of a polygon in Postgis

I have a PostGIS algorithm that writes a table with "pixelated" polygons, that I will call "clusters". My idea is to smooth the edges of these clusters using concave hulls (ST_ConcaveHull). To do ...
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128 views

Databases supporting intersection of multipolygons and a set of points

Currently we use PostGIS to store thousands of MULTIPOLYGONs and we can then use ST_Intersects to return any that rows contain any point in an input collection of points. Are there any other open ...
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135 views

PostGIS - How do I create a line that directly connects two earth points without travelling over a geodesic?

In PostGIS 2.1.1, I've noticed that if I create two distant earth points with equal altitude and then create a line connecting them, as I gather interpolated Z coordinate data along the line my Z ...
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1answer
112 views

SDO_Inside equivalent in PostGIS for 3D objects

I am looking for a solution for querying a point whether it is located inside a 3D object or not. If the point is located on the surface of 3D, I could use ST_3DIntersects or ST_3DIntersection. But, ...
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230 views

Spatial joining syntax

A standard PostGIS point-in-polygon query might look like this. (example tutorial) SELECT p.*,b.polyname FROM points p, shapes s WHERE ST_Within(p.the_geom,s.the_geom) Imagine this was not a ...
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367 views

How to calculate the shortest distance for multiple source and targets using PgRouting?

I have a table with points and a road network which includes driveways (where you enter the highway). I want to find the point which is closest to a driveway. So I was thinking I can calculate the ...
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1answer
336 views

How to generate pgrouting source and target with OSM?

Is there anyone here can explain me more details for pgrouting's source and target? I'm wondering how to generate with the given lonlat in OSM PostGIS entities. In pgrouting's website, they are ...
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1answer
373 views

Empty geometries in GEOMETRYCOLLECTION

I just noticed some strange behavior in PostGIS, with respect to WKT parsing. A GeometryCollection containing 1 or more empty geometries postgis_test=# SELECT ...
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2answers
182 views

Does PostGIS have separate implementation of GiST index from PostgreSQL?

I want to know if PostGIS has a separate implementation of GIST index or it reuses the GIST index implementation provided by Postgresql?
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1answer
235 views

Why is the QGIS 2.2 database tab missing?

I have recently installed QGIS-2.2.0 but the Database tab in the top-menu bar is missing. It looks the main reason is missing libgdal1h library. But when I am installing it, it's removing ...
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1answer
723 views

PostgreSQL : finding all lines intersecting with a polygon

I am totally new in the world of GIS but as a student surveyor I am working on a project using postgreSQL and PostGIS. I have one database with all the roads of my country (lines), and one database ...
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1answer
179 views

When would a PostGIS geometry compare using ~= return true when ST_Equals returns false?

I have a couple of featureclasses in a 10.2 geodatabase/PostgreSQL 9.2.2 database and I've been struggling with the FeatureCompare tool--it is telling me geometries are different on some features ...
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4answers
205 views

Linking up GPS points taken from rail network

Bit of a newbie here, trying to work out whether any PostGIS functions can help with my task. Apologies in advance if my use of GIS terminology is not up to scratch yet. I have a large database of ...
2
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1answer
90 views

PostGIS: How to understand ST_RasterToWorldCoord() right? (PostGIS 2.0)

After putting raster in to postGIS by this Thank @Sorin for helping me out! Now, I want to output raster tile, then view it on QGIS. But the problem is the output of ST_RasterToWorldCoord(raster ...
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1answer
143 views

How to change table name of command raster2pgsql

I am completely newbie with GIS and PostGIS as well I'm trying to load raster into postgreSQL with raster2pgsql. It runs well. However, the table name of the raster is generated automatically. For ...
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1answer
453 views

GeoWebCache seed task dies immediately after being submitted

The data comes from Geofabrik's Brazil slice: http://download.geofabrik.de/south-america/brazil.html Imported into a PostGIS DB with osm2pgsql. GeoServer is 2.4.0, running on latest Tomcat 7.0.x, on ...
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2answers
393 views

ST_ShortestLine gives different results for 4326 and 900913 projections. Which is correct?

I'm trying to get my head around how ST_ShortestLine (and ST_Distance and ST_LineLocatePoint) work with different projections. The result for the shortest line differs depending on which projection I ...
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1answer
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GeoTools and PostGIS with ESPG:3857

I'm trying to use both PostGIS and GeoTools with the same ESPG:3857 projection, however, it looks like the projections in PostGIS and GeoTools differ. This is what I have in PostGIS: PROJCS["WGS 84 ...
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3answers
960 views

Why can't I open postgis layers in QGIS?

I've set up a table in PostGIS using OSM data (converted using osm2pgsql). I know this database is good, because I'm able to import it and work with it in TileMill, but whenever I try to interact with ...
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400 views

Raster Tile Merge Performance of PostGIS 2.0

I'm attempting to intersect Australian Census boundary polygons with the 1" SRTM DEM (10.5bn points across Australia), and output the result as a single raster image on the fly. The DEM is stored in ...