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

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Postgis: Conflation of two vector layers into a single layer

If I have table A that I consider to be definitive and table B that may have some elements missing from table B but also has geometries that are "close" to those in A that I want to ignore. How could ...
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16 views

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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527 views

Converting polygon values to a vector grid using PostGIS

What is the best way of converting a value from irregularly shaped poylgons to a polygon grid using PostGIS? I have a set of polygons that look like this: and I would like to overlay a grid on ...
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333 views

Find start of river

Edit: Follow-up question here (= Find headwater polygons). How can I determine the start of a river in PostGIS? I have a river network (Multiline) and want to find the startpoints of the rivers. ...
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1answer
8 views

ST_AsLatLonText () rounded

I know this is a POSTGIS question… I set a field with UPDATE members SET latlong_degree = ST_AsLatLonText (the_geom) But the result is (for example) 48°37’41.742”N 9°17’55.716”E The seconds part ...
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271 views

libgdal1 and libgdal1h conflict

I am on Ubuntu 14.04. When I am installing PostGIS-2.1, it's asking for libgdal1 library. But when I am installing libgdal1, it's removing grass and gdal. Can someone please guide me how to install ...
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1answer
123 views

Creating a postgis database a GML application schema

Is there any open Source tool(automated or semi-automated) that converts GML application schema to a POSTGIS database/table .Specifically I have a huge application schema containing many ...
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35 views

postgis - managing single dataset, multiple coordinate systems

I am setting up a forest inventory database that aims to store information about forest plot data from various countries. The current project is in Mozambique, others are in Laos, etc. Each project ...
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12 views

How to get changeset tag from .osm file into PostGIS enabled Postgres db

End goal: visualize geographic data from .osm file with QGIS by adding PostGIS layers which include changeset information. I have used osm2pgsql successfully to populate PostGIS and visualize the ...
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3answers
84 views

Spacing a set of points

I have a shapefile of a set of points that I want to space out. I DO NOT want to do this using line interpolation as I run the risk of placing a point where there wasn't one before. I can load this ...
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23 views

How to create unique plane with PostGIS?

How to create a unique plane, with (x , y ,z) as center and a vector as normal, in PostGIS? I already saw "Make3DBox" function, but it does not make a unique one.
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33 views

Geohash36 for PostGIS

i was wondering if anyone created a ST_GeoHash36 function inside postGIS, i know the ST_GeoHash + ST_GeomFromGeoHash functions exists, But i need the geohash36 function inside postGIS, i need a ...
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44 views

PostGIS ST within does not exist

I'm quite new to postgresql and postgis so this error will probably due to some rookie mistake. I want to run the spatial query ST_within. When I describe the query like this SELECT nw.entity_id AS ...
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28 views

Can you do aggregate functions among nearby geometry in PostGIS?

I want to do aggregation based not on group but on geometry, is that possible in PostGIS? For example to calculate max, min, average price for all listings that's nearby a geometry point, how can I ...
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2answers
39 views

WFS 2.0 transaction

I am using WFS-T in a mobile application to commit changes to a postgis database via geoserver 2.6. I build the http requests myself (not using any framework like geotools or openlayers). I already ...
3
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1answer
46 views

PostGIS multiple conditional statement on spatial join

I want to make a multiple conditioned spatial query in PostGIS 2.0/PostgreSQL 9.3., OS Windows 7. There are 2 tables, cadastre (Polygon) and roads (Linestring). Query: Select the sum (one number) of ...
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1answer
24 views

Visualising a raster PostgreSQL table in QGIS

I have imported a raster tif image into PostgreSQL with this command: raster2pgsql -s 32643 -I -M filepath.tif -F -t 100x100 public.databassename > filepath.sql And imported the output SQL file ...
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2answers
36 views

Y-coordinates offset in Tilemill

I own a project created with TileMill in SRS 900913. The data source is a Postgis database with the same SRS. When I'm loading the file generated with TileMill (mbtiles) in QGIS and I'm putting under ...
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58 views

Spatial query too slow to handle bigger OSM extracts

I'm trying to compute some statistics for OSM data using PostgreSQL 9.3.5 and PostGIS 2.1.4. I started with a small bavaria extract which I downloaded from Geofabrik. The db schema is the normal API ...
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40 views

Create polygons enclosing same number of points on PostGIS

I have a geodatabase on Postgis with points representing customers, what i need is give a number of customers, lets say 100 and it need to generate polygons enclosing 100 clients each one. I only ...
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122 views

N Nearest Neighbours efficiently PostGIS/Python

The data is worldwide about a million points, lat/lons, with an id and an importance value (0.0 to 1.0), and it's limited to being on land. Ideally I need to cluster all 1 million points into 100,000 ...
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17 views

Convert Postgis tables to DWG

Is there a simple way of converting a postgis table to DWG for a given table name? Regards,
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79 views

PostGIS ST_Union Performance

I'm trying to execute a 'dissolve' operation in PostGIS using the ST_Union command. The input layer is admittedly quite large and complex. By 'large' I mean 57,771 features, with number of vertices ...
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200 views

ST-Links convert Feature Class to DB Table error

I'm using ArcMap with the ST-Links SpatialKit Conversion tool to convert a Feature Class to a DB Table. But I'm getting an error: ERROR: 42601: type modifier is not allowed for type "geometry". I ...
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1answer
272 views

Using ST_MakeEnvelope over the dateline

I'm using ST_MakeEnvelope in PostGIS to try and make geometries that cross the international dateline, but they are making a shape that wraps the other way around the globe. The geometry I want is ...
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95 views

Openlayers wfs no fid being passed from tinyows

I have a webapp - OpenLayers<->tinyows<->postgis. With 1 layer I have a problem. On localhost all works well - here is a snip of the xml I get back: <gml:featureMember> <tows:trad ...
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33 views

Problem in importing shapefile to Postgis with postgis Shapefile manager

i have a problem with importing my shapefile to postgreSQL, it's a poroblem with the encoding, here's the screenshot: i tried to change encodingin "options" buti get this message: "Failed in ...
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3answers
62 views

How can I export data containing umlauts from PostGIS to shapefile, without losing the umlauts?

I am exporting my Finnish (Finland) data from PostGIS to esri shapefile. I am using the PostGIS Shapefile Import/Export Manager and I don't see any way to specify the encoding of the shapefile's ...
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199 views

Polygon grid shape file for landmass

I am interested in generating a polygon grid shape file for the landmass of the world. What I have presently is two tables in postgreSQL. Table 1: Coastal area shapefile ...
3
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1answer
47 views

How to display OSM relations (in QGIS) from osm2pgsql populated PostGIS DB

I have a PostGIS DB populated with OSM data (osm2pgsql, standart.style). Now I would like to display a hiking trail (http://www.openstreetmap.org/relation/51855). It would also be fine, if I just ...
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2answers
195 views

Coordinate System Google Maps API

I am making an application in java using GMaps4JSF where the person will enter the address on the map I'll take this coordinate and consult on my postgis base regions in which region this point is ...
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33 views

PostGis - BBox -vs- ST_intersects Queries

CartoDb Recommend here that the following query is faster than an St_intersects Query SELECT * FROM {table_name} WHERE the_geom && ST_SetSRID(ST_MakeBox2D(ST_Point(-73.9980, 40.726), ...
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263 views

Where can I find PostGIS error codes?

Using ST_Contains in where clause sometimes gives me error messages like ERROR: GEOSContains: TopologyException: side location conflict at 37.3706 55.7882 For now I can't guarantee validity for ...
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2answers
253 views

can't geocode with PostGIS 2.1.1

I don't know where's the mistake... I am using the process from the PostGIS documentation (http://postgis.net/docs/manual-2.1/postgis_installation.html#loading_extras_tiger_geocoder) . I created a ...
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1answer
249 views

How to compute the smallest network that connects all points using PostGIS?

I have a set of postgis scripts which generates two tables - one of a set of points and the second a set of roads which surround them. All data is in the same projection and both outputs are stored in ...
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1answer
13 views

Raster2pgsql overview method

What is the method used by Raster2pgsql to create overview? I couldn't find details in the docs. Nearest neighbor isn't a very good choice for the dataset I'm working on, but that seem to be the one ...
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100 views

Polygon dynamic grid creation for a shape file

I have used QGIS Vector->ResearchTools-> Vector Grid to create a 1lat x 1 long grid for the landpolygon shape file (from osm). Now, I am interested in creating dynamic grid for the original ...
3
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2answers
678 views

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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1answer
24 views

Querying Postgis data in R using dplyr package

Does anyone have a workflow for querying postgis data in R using the dplyr package? R doesn't like the spatial columns in postgis data so can't read them in like a postgres table. I get the error ...
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1answer
19 views

How to use ST_Transform when inserting new row?

I have written a script which reads a CSV file with lat/lon coordinates in WGS84 and inserts them into a table in PostGIS. What I want to do now is to change the insert query in order to make a ...
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26 views

How to choose data type and SRID, for coordinates from different sources, in a medium size zone

I'm developing an application. In the database I need to store coordinates for many places, in the north-east of Italy, but the area could expand in the future. This coordinates will come from some ...
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1answer
190 views

Geoserver OSM data Imported via osm2pgsql - most efficient tables to use to style roads

The Osm2pgsql importer for OSM data to Postgres results in two tables for ways, one called planet_osm_roads and a second one called planet_osm_lines The Osm2pgsql documentation states that the ...
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37 views

postgis - get nth point of a polygon

I would like to create a postgresql function to correct geographic coordinates inside a polygon that are outside the -180 to 180 range of longitudes. To do this, I thought I would create a function ...
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2answers
247 views

Connect to PostGIS using SEXTANTE in QGIS

I have a localhost PostGIS database that I would like to use with SEXTANTE in QGIS. I can connect to the database just fine using "Add PostGIS layers...", but when I try "PostGIS execute SQL" in ...
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1answer
26 views

How to choose a SRID and what is its meaning? [duplicate]

I'm new to GIS, in PostGIS, and I'm struggling with the SRID concept. How do you choose a SRID for a database column? This is making me crazy. Why do I need to choose a SRID? What's its meaning? ...
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12 views

Walking-Driving area with Leaflet,OpenLayers

Could be possible to get a walking or driving distance area using pgr_drivindistance,pgr_alphashape and/or pgr_pointsaspolygon when an user click any location on map with Leaflet or OpenLayers?. I ...
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2answers
69 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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1answer
550 views

How to view a 155 MB raster stored in PostGIS?

I am using the following command to load a raster into a postgres database: raster2pgsql -I -C -e -Y -F -s 3086 -I -C -M myraster.tif myraster -F -t 30x30 | psql -U postgres -d database -h localhost ...
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4answers
73 views

Postgis don't use spacial-index with st_intersects

I imported the data from openstreetmap using osm2pgsql and copied it another table structure. If I made a query for containing rows using st_intersects, st_contain or someone else, postgis don't use ...
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1answer
42 views

QGIS 2.6 how to prevent user to drop a postgis table

Does anyone know how to prevent user to drop a postgis table? I have a vector layer imported from a postgis2.0 database, and one of my users drop it accidently. Fortunate I had a backup, but i don't ...