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

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Is there a significantly faster way to buffer than arcmap? [duplicate]

I hope this question is appropriate here and I apologize if it is more of a discussion question than a specific technical problem. I have to buffer 150,000 polygons for a real estate project. While ...
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How to extract mountain peak points from a given digital elevation model?

For past couple of days, i m trying to determine how many mountain peaks are visible (line of sight) from a given location using POSTGIS. The data i have is DEM for Swiss and address locations from ...
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Setting geometry types importing to PostGIS with OGR

I'm using ogr2ogr to import data into a PostGIS database. Each dataset I need to import has (theoretically) the same exact data structure, but it appears that they are not the same geometry types. ...
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How do I get the area of a WGS84 polygon in square meters?

The following gives me the area of the polygon in square degrees: SELECT ST_Area(ST_GeomFromText('POLYGON((871325.790874952 6105405.3261047,871418.748307692 6105359.72944624,871346.22022442 6105215....
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927 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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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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935 views

Downloading raster data into python from postgis using psycopg2

I have raster data in a postgres table that I want to get into python as a numpy array. I am using psycopg2 to connect to the db. I am able to download the data but it comes back as a string (probably ...
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Very poor performance of QGIS and PostGIS2. User error or feature? [closed]

I have a large table in Postgis2. It has >500 million polygon, line and point features all happily living in there and the table performs brilliantly in other GIS. I am now trying to just add that ...
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Do large vertex counts cause performance issues?

I have a table of several thousand tuples - each tuple has a geometry column. The problem is, these geometries have a large vertex count. The max vertex count is 400, while the average is 200. ...
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How do you calculate lat/lons from a PostGIS table which has a projected coordinate system?

I have a PostGIS table in a projected coordinate system (EPSG: 28355 or MGA94 Zone55). In QGIS (with the PostGIS manager plugin) I calculate a coordinate by performing the following SQL "UPDATE ...
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How to achieve equivalent to Dissolve from ArcGIS for Desktop using ST_Union?

I am trying to achieve an equivalent to the Dissolve tool from ArcGIS for Desktop using ST_Union from PostGIS but it seems I am not getting expected result. I have one table which has certain ...
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942 views

Data visualization and maintenance tool

Background Looking to leverage an existing GIS system for exploring organizational data. Architecture The following figure represents a high-level overview of the system's desired features: The ...
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Raster data on PostGIS

I need to publish raster and vector data through GeoServer WMS service and I have already chosen PostGIS as datasource to keep vector data. Now I would like to know what is the best practice to work ...
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540 views

Clarification of Logical Operators in a PostGIS Database

The following query returns this result: select count(*) from a , b where a.geom && b.geom; count ------- 66514 On a postgis 2 database. What does the logical operator AND (...
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How to load Shapefiles into a remote PostGIS db using command line?

Can we import a Shapefile from a system which doesn't have PostgreSQL installed (client machine) into a system having PostGIS installed? I am getting problem with 'shp2pgsql' and 'psql' since both ...
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How to get smallest line segments from intersection + difference of multiple overlapping lines?

Inspired by this question, and this excellent answer. I have multiple overlapping lines and want to extract the complete intersection of them. So from this sample data SELECT id, geom INTO stackex ...
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798 views

How to findout direction PostGIS

I want to find out the direction from the 2 points from postGIS database. Please see the attached image. I want to find out the direction from the mainPt to any point. But want to get the result as NW,...
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672 views

Promotion radius in miles around venues using PostGIS

Bear with me as I'm new to PostGIS and GIS in general. I also don't know the domain well enough to create a good title for this post! Here is what I'm trying to accomplish: I have Venues in my ...
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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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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. ...
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228 views

Smallworld > FME > PostGIS > QGIS, handling geometry types

I'm migrating data from Smallworld via FME/SpatialBiz Plugin to a PostgreSQL/PostGIS Environment and then trying to open the resulting tables with QGIS 2.12.1. Problem arises, because Smallworld ...
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Mapnik + OpenStreetMap + Shapefile with Raster Images + Mod Tile + PostGIS

I am new to GIS. I have a Shapefile (.shp, .shx and .pbf). The .pbf file contains path to PNG files located on my machine only. I was able to save the Shp data to PostGis via Shape2Gis tool. Now ...
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WFS Caching / Back button

I'm using WFS protocol on Vector layer / GeoServer / PostGIS Currently the map is refreshing and calling new requests whenever i do anything like searching or drawing and when i move back to a part ...
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Merging polygons that intersect by more than a specified amount

I am working with a dataset that contains a subset of property boundaries in a local government area, thus my dataset is made up of several thousand properties but not all are touching. Since it is a ...
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How to set posgis default sequential value in a QGIS “editable” view?

Introduction In a QGIS project I have a VIEW, that I want to became editable (I'm trying to replicate the versioning system used DB Manager with some tweeks). Therefore I created a few rules to ...
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Error creating a spatial database. ERROR : could not load library “/usr/pgsql-9.1/lib/rtpostgis-2.0.so”

I am running PostgreSQL 9.1 with Postgis 2.0 on Fedora 15. When trying to install the raster support, psql -d mydb -f rtpostgis.sql -v ON_ERROR_STOP=1 I get the following error psql:rtpostgis....
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Creating polygons from line segments using PostgreSQL and PostGIS

Is there a PostGIS function that creates polygons from multiple line segments? I want to convert the pictured thirteen lines to four polygons. All lines belong to the table "boundary" (gid, geom). I'...
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733 views

PostGIS: ST_Transform function conversion problem

I'm inserting map data from a GML file with srid EPSG:27700 into a PostGIS database table with srid EPSG:4326. I'm using the ST_Transform function as in this snippet: ST_Transform(ST_GeomFromGML('&...
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153 views

Adding vertices to polygon in PostGIS?

For example I have rectangular polygon (4 vertices). I want to add mid-point on each line of the polygon, so in total now I have 8 vertices. And from them I want to build new polygon who will have ...
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Merging linestrings in QGIS using PostgreSQL and PostGIS

I've to merge all linestrings from a PostgreSQL table "river" where not more than two start-/endpoints are overlapping. In the illustration below I use a "M" to mark all linestrings that needs to be ...
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PROJ4 / PostGIS transformations between WGS84 and NAD83 transformations in Alaska

I'm trying to implement the recommended WGS84 - NAD83 transformation for Alaska using PostGIS. This post: Geographic Transformations in Alaska Between NAD83 and WGS84 indicates the proper ...
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PostGIS Error: type “geography” does not exist

I just upgraded my development machine to Windows 7 and am therefore reinstalling PostgreSQL and PostGIS. I used the Postgres Plus installer, as recommended on the Postgres website, and followed this ...
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986 views

Dynamic SLD styling - unique colours for linestrings

I have a postGIS table that looks like this: (plus a 'track' geometry column, a linestring for the vessel's track) sampling_interval | voyage_name | start_time_utc | id | ship_name | ...
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445 views

PostGIS - ST_Within or ST_Disjoint performance issues

I have a table of about 150,000 points in PostGIS with a spatial index and a SRID of 27700 (OS). I want to select the points that fall outside England and Wales. I have a multipolygon table with ...
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183 views

How to add time and elevation dimension attributes to Geoserver rasters?

In geoserver, when I edit a postgis raster layer and click on the Dimensions Tab, I can't enable either of the Time or Elevation dimensions. The following message appears next to each of the ...
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convert list of points to line or polygon

I have a list of Points in a PostGIS table. The rows can be grouped by a date something like: myTable id INT date DATE lat NUMBER lng NUMBER geom GEOMETRY(POINT) now I need a table where all ...
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Postgis shapefile loader 2.1 error: dbf file can not be opened

The .shp, .dbf and the rest of files are fine, I open them in QGIS, AGOL with no problem. In fact, I've tried 3 different layers, and get always the same error. Anyone can please help, as I really ...
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625 views

How to install PostGIS correctly with OpenGeo Suite 4.0 community edition on Windows 7?

I have installed the OpenGeo Suite community edition, version 3, onto Windows 7 multiple times in the past, with virtually no problems. With the latest version of OpenGeo Suite (4.0.1) (which ...
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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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631 views

How fill length and feature count in PostGIS table for each polygons

I'am new to PostGIS/PostgreSql. I have a database which containts two shape-files : polygonal layer towns and linear layer of roads To calculate the length and feature count of 'Streets' inside ...
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738 views

How to merge connected lines with same direction (PostGis)

I am looking for a way to join all lines that are connected, have the same direction, i.e. start point of one is end point of the other, and share some common attributes. In fact, I want to connect ...
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1answer
295 views

How can I move along a line (or path)?

Given a line (street, railroad, river...) I want to simulate a moviment inside this line. Example: See this picture: Say I'm in "Nagqu" and want to move to "Kunlunqial". In a time (t=0) I'm in ...
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1answer
347 views

st_clip and gdal_translate: “Error browsing database for PostGIS Raster properties” - Why?

Im using shell-script, postgis2.0 and gdal for trying to clip raster apart, using an overlapping raster and a the_geom-object. At first I create a view to clip the overlapping part of the raster. It ...
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Compare features in PostGIS with updating attributes

I have two polygonal layers: "existing" and "modified". Attribute table of "existing" and "modified" layers have same column "feature_id" - number of feature. Please help me create query which write ...
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455 views

How do I catch PostGIS/PostgreSQL RAISE messages in QGIS?

I have a trigger set up in PostGIS/PostgreSQL which will show a RAISE WARNING when an inserted or updated polygon is within a certain distance of some predefined planning constraints. I want this ...
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238 views

PostGIS Raster: Outputting raster into GDAL supported file?

I have import a raster into my postGIS database via raster2pgsql. My raster tiled to 100x100. Now I'm trying to export (output) the raster to GDAL supported file (for example: PNG). Following the ...
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spatial query st_contains postgis

This seems too simple to be asking this but I am really new to PostGIS/Postgres have been going around in circles with this. I am performing a really simple spatial query where I would like to make a ...
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1answer
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geoserver wfs insert error

I keep getting an insert error from geoserver when trying to save a point, poly etc etc to my postgis table. any ideas, my code is below var Projection = new OpenLayers.Projection("EPSG:4326"); ...
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Access PostGIS Raster layer through mapserver

I am trying to use a cgi script calling mapserver to display a raster layer that is stored in a PostGIS database. However, only a blank white image is returned and I don't know where the problem is. ...
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Geoserver, OpenLayers so slow for WFS! Why?

I am displaying 100 000 points in a layer via WFS protocol. I need about 5 minutes. However, 100 000 does not seems so much... My points are stored in PostGIS, in a column defined this way : ...