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

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2answers
752 views

How to group connected linestrings in PostGIS?

I have a table of streets I've selected based on a set of attributes (let's say it's speed_limit < 25). There are groups of streets that are locally contiguous; I'd like to group these sets of ...
3
votes
2answers
2k views

How to get the data type of each column from a postgis table

I need to get the column data types of all columns in a table, including the geometry types. What I wanted to know is if there is a function or SQL that gives something like this: column_name | ...
5
votes
0answers
80 views

Compute visibility graph on sphere

I have a PostGIS table with some polygons (stored using the geography data type). They represent regions on a spherical earth. For each pair of vertices chosen from among all the polygons, I want to ...
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0answers
34 views

Use pgRouting with a PaaS

Is it a way to use a postGIS/pgRouting enabled database with a PaaS like Windows Azure? If not, do you know alternatives?
1
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2answers
552 views

Searching planet_osm_point by longitude and latitude

I used osm2pgsql to import data into my PostgreSQL database and it put gave me the following 4 tables, planet_osm_point, planet_osm_line, planet_osm_polygon and planet_osm_roads. I have looked at ...
0
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1answer
137 views

TileStache:TileStache.Core.KnownUnknown: Couldn't get a layer from data source!

I want to use tilestache to get geojson files. I hava run tilestache-server.py -c tilestache.cfg ,and it works well. However,I want to get tiles from data stored in postgis. Maybe it will need to run ...
2
votes
1answer
42 views

Only Draw Geometric Objects Above 8th Parallel North

I have many geometric objects (in both SRID:4326 - the_geom - and SRID:3857 - the_web_geom - in PostGIS extension tables of PostgreSQL), including country boundaries, for the country of Ghana and I ...
1
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2answers
59 views

Getting OSM data for a particular jurisdiction

I'm trying to make a street map of New York City (and only New York City). I've downloaded OSM data for the area (from here), but it contains lots of data from the suburbs. Currently, I've loaded ...
0
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1answer
63 views

Export .dbf maintaining column data type

I require a shapefile's .dbf to contain two types of text columns VARCHAR(n) and CHAR(n) to meet specs (attribute format) of gov receiving body. Have to send them the .shp, .dbf and .prj. Within ...
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0answers
95 views

Focal Mean of neighbors using ST_DWithin on points in PostGIS

I'm trying to calculate focal means on a grid of points in PostGIS. I know that a raster calculation would be more efficient, but I only need to run the algorithm once to get the data, so I don't ...
1
vote
2answers
71 views

How can I speed up these queries

I am trying to make some calculations using PostGIS and PostgreSQL. There are 3 important tables : wbn, wgo and wvb. These tables have about 500.000 objects in them (geometries). The problem is that ...
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0answers
72 views

PostGIS 3D Extrude function

I selected buildings from OSM (which represents my city). I insterted a new column 'height' and I filled with a random number exactly number 2, so every building have 2metres altitude. Buildings are ...
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0answers
24 views

How to simplify a polygon down to X amount of points?

If I have a polygon that has 100000 points, how can I calculate what the tolerance should be to simplify it down to 1000 points using ST_SimplifyPreserveTopology?
0
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2answers
214 views

How to get feature from PostGIS to OpenLayers with ASP.NET?

I need to show my feature from this table in PostGIS in my ASP.NET web page web. Has anyone done that?
0
votes
1answer
129 views

How to get a distinct pair of column values based on minimum of another (computed) column?

I have two tables with point geo data, one (sfc_obs) with weather stations (names), one (smos_grid) with satellite pixels (dggs), and I'm trying to find which dgg is closest to each name using ...
1
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2answers
106 views

What index to use in this situation

I am working with 3 tables with 3 x 500 000 rows. There is one column that gives each object a unique ID (UIDN), there also is a column with the geom data (the_geom). There also are some other columns ...
3
votes
1answer
118 views

MS SQL Server 2012 to Postgresql

How to use MS SQL Server 2012 spatial database in postgresql using foreign data wrapper?
2
votes
0answers
161 views

Raster slightly displaced after exporting from PostGIS database

With the following queries I've exported a raster (GTiff) from my postgis database: 1.Creating a large object: WITH buffer AS ( SELECT id, ST_Buffer(geom,50) AS geom FROM ...
1
vote
1answer
120 views

How to split/divide linestrings of larger lengths in postgis

I want to split/divide linestrings in my data. I have roads data and I want to have every road segment having length not more than 250 meter. Check the shape length of this particular line feature. ...
1
vote
1answer
161 views

Trouble using ogr2ogr w/ -s_srs to combine inconsistent EPSG files into my postgis DB

I'm having trouble combining shapefiles from TIGER and different local governments into a single postgis db to query legislative locations. I've imported all data to multipolygon geom, but found some ...
1
vote
1answer
124 views

3D functions with SFCGAL in PostGIS

I have this setup: "POSTGIS="2.1.2 r12389" GEOS="3.3.8-CAPI-1.7.8" PROJ="Rel. 4.8.0, 6 March 2012" GDAL="GDAL 1.9.2, released 2012/10/08" LIBXML="2.7.8" LIBJSON="UNKNOWN" TOPOLOGY RASTER" on ...
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2answers
406 views

What is the best way to take a WKB value in SQL Server Management Studio and create a PostGIS geometry in PGAdmin III?

Normally, I would just use WKT strings but I'm investigating some possible geometry weirdness with the Text methods in SQL Server. I would like to copy/paste the WKB values from the SQL Server ...
1
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1answer
53 views

Strategies for managing (and ultimately merging) duplicate business locations in a spatial database

I am working on a project right now that involves using multiple (very large) "location directories" to identify with the highest possible inclusiveness, a diverse set of business locations. These ...
2
votes
1answer
906 views

How to save a google map direction into a postgresql/postgis database?

I have taken a direction(route) from google map. Can I save this resultant direction/path/route to my postgresql/postgis database? How?
2
votes
2answers
71 views

Do I still have to use a template DB for PostGIS?

createdb mydb -T template_postgis Is this -T template_postgis still necessary in new versions of PostGIS? I never saw this db being different, it always has those 3 sql files you run there. Is this ...
0
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1answer
249 views

How to ensure that Tilemill interprets my postgis query as intended?

One of my layers (a postgis query from my local osm2pgsql database) is being translated incorrectly in Tilemill. The query is attempting to select the way, the area of the polygon, and the sport=* ...
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2answers
421 views

PostGIS to GeoJSON with GDAL: how to get lat/longs?

I'm trying to convert line features from PostGIS to GeoJSON files, as follows: from psycopg2 import * from subprocess import call conn = connect(dbname='gis') cur=conn.cursor() cur.execute("SELECT ...
3
votes
1answer
79 views

Extra detailed bounding polygon from many geometric points

I have a database of around 100,000 postcodes each with lat/lon which I have converted to geom type in PostGIS. Each postcode also has one of 5 "regions". I wish to generate an accurate bounding ...
1
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2answers
84 views

How to find all features in one table that intersect features in another table in PostGIS?

I have two tables, boundary polygon table and location point table. I need to find all boundary polygons that contain at least 1 location point. What is the proper way to do this in PostGIS? I tried: ...
1
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1answer
35 views

Is there a way to edit the host name of Postgis layer?

Recently I change my server to a remote host. That's means all my work there I used Postgis layers, the host name at the source is set to 'localhost' and I need to change to 'remotehostname'. The ...
1
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1answer
105 views

convert XML to PostgreSQL using MATLAB

In a weeks time I should be able to transfer the GIS data provided in the XML format to PostgreSQL database. I have prepared the PostgreSQL database (empty) and looking at Matlab scripts. (I am on ...
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0answers
155 views

qGIS' Database Manager “Load as New Layer” Option Not Working

I'm trying to visualize some of my database queries on qGIS. I run a valid SQL query which returns a subset of my table that should be easily loaded as a layer. I then check "Load as new layer," ...
2
votes
2answers
457 views

Update/refresh edited PostGIS table in QGIS

I imported a PostGIS table (with geometry) from my PostgreSQL database as a layer in QGIS. Later, I edited the table using PostgreSQL UPDATE commands. Is there a way to quickly update (like a refresh ...
3
votes
4answers
229 views

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 ...
2
votes
2answers
442 views

Conversion of point grid to a raster with open source tools (Gdal, QGIS …)

I'm looking to do something which seem simple to me, but I haven't found a solution since 2 days I looked for. I've got a Postgis DB with lot of points (WGS84) spaced of 100 meters which cover a ...
2
votes
1answer
209 views

pass an array of geometry to postgresql function

I am trying to pass an array of geometry to a postgis function using JDBC with JAVA: CallableStatement proc = conn.prepareCall("{ ? = call somefunc(?) }"); ...
1
vote
2answers
114 views

PostGIS ERROR: getPoint4d_p: point offset out of range

I have a set of streets (LINESTRING) in a PostGIS 9.1 PostGIS 2.1 database. I need to obtain points from the lines, on the right and on the left of the street. I offset the lines with: ...
1
vote
1answer
189 views

Finding closest Intersection between line strings (PostGIS)

I want to find the distance between one point (excavation sites) and a line (rivers) for the cardinal directions. What I thought would be the easiest way is to draw lines between the excavation site ...
0
votes
0answers
94 views

OpenStreetMap Road and Polygon Data as 1x1 Degree Shapefiles

I am working on a global project for which I want to use OSM data as a model input. I am looking for advice on the best way to produce 1x1 degree WGS84 shapefiles from either regional extracts or the ...
1
vote
1answer
156 views

ST_Union to merge tables containing lines?

I have to build a street network with Postgis that will be used with pgrouting. I have two tables: 1) the_network (182 lines): is a MULTILINESTRING table. Having columns road_name (varchar) / ...
0
votes
0answers
38 views

Credential Dialog, disabling default Realm information messages disclosing password

I'm using the QgsCredentialDialog for determining user access to the database. When a user is failing to log in correctly the log in credentials are shown in the dialog (Fig. 1). (success, uname, ...
1
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1answer
52 views

Trying to understand / troubleshoot intersection behavior of postgis

I'm trying to calculate the percent of intersection between two polygons using postgis. I was able to do so successfully for 90% of my polygons, but about 1500 have very unexpected values. I ...
4
votes
2answers
351 views

Editing PostGIS topology in a web browser

I am trying to conceptualize the best process for editing topology from PostGIS in a web browser. Ideally what I would like to accomplish is the loading of a topology (imagine the lower 48 states of ...
3
votes
1answer
453 views

ST_Buffer returns inaccurate results with radius of over 1 meter

I have a specific location: lat, lng and accuracy(meters) I want to return a geography object that will represent a polygon that surrounds this point with a given radius that will be equivalent to ...
2
votes
2answers
331 views

Extract a PostGIS dump from OSM with a particular tag

I'm new to OpenStreetMap. I want to extract all restaurants from Switzerland with their capacity if available. I am using osmosis. I tried: osmosis --read-pbf file=switzerland.pbf --tf accept-nodes ...
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1answer
56 views

Weird ST_Contains behaviour

I'm creating a polygon and then checks whether one of the origin points is contained inside the polygon. To my surprise, I get False (?!) What is wrong here? SELECT ST_contains(ST_GeomFromText('POINT ...
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2answers
97 views

Can 'Source' and 'Target' in the roads table for routing be duplicate?

I am using pgr_ksp for finding multiple paths for single source and destination. I am wondering if 'source' and 'target' in a roads table are unique or not. because when i am doing routing on my road ...
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0answers
23 views

Query from plugin that shows result on Map and in Attribute Table

I'd like to create a plugin that performs a static (no user input required) query that, based on a condition, selects all the features on the map and displays these in the attribute table. I have the ...
1
vote
1answer
99 views

PostGIS transform geometry with long crs

How do i transform a geometry to a new geometry with a crs like urn:ogc:def:crs:EPSG::25832 st_transform(geom,integer srid) obviously doesn't work since my srid is a string found a solution ...
2
votes
1answer
234 views

How to set tolerance value of ST_Intersects query in TileMill?

I want to place river names in Tilemill. I use "text-dy" to displace label from the center line of a river. But for labeling polygonal rivers, names extracted from lines are used too. So at a small ...