Tagged Questions

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

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postgis — return records sorted by size of st_intersection

I have two sets of spatial records in two different tables. I'm in rails so I'll show my code in that way seeing that its source: one set is CensusPlace records, which are US Census Tigerline ...
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1answer
102 views

Import raster into PostGIS using Python

I am trying to import information from a Bathymetric Attributed Grid (BAG) file into PostGIS using Python and psycopg2. I'm working, for now, on a Windows box with pre-compiled packages, so I don't ...
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2answers
117 views

ST_Expand return different results depending on meters [duplicate]

I am very confused by getting different results from st_expand (srid 4326). I want to do a search within a bounding box, therefore I pass a point and I'd like to provide distance in meters in order to ...
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0answers
45 views

PostGIS automatically creating geometries after importing using QGIS DB Manager

I have a shapefile consisting of linestrings, in which some of the features have null geometry. Yet, after importing it to PostGIS, using QGIS' DB Manager, a geometry is created for those features ...
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1answer
110 views

Add GPS tracks directly to a PostGIS table

Disclaimer: I am a total GIS newb and I have a use case I have not seen elsewhere. Background: I drive country roads looking for old building, cemeteries, school houses, etc and I record the ...
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1answer
153 views

Local Copy of OpenStreetMap of my City in PostGIS Database

I would like to use OpenStreetMap vector data for land cover analysis in my city. Here is my goal: I set up a PostGIS database with the city area extent (around 20x20 km) on my server. I will ...
2
votes
1answer
131 views

Using PostGIS functions in ArcGIS Desktop for Layer Definition Query?

I am connecting ArcGIS Desktop 10.2 to Postgis 2.0.3 with PostgreSQL 9.2.4. No SDE. I can load data with no problems and access the data in ArcMap. However I can't seem to use PostGIS functions within ...
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2answers
88 views

How do you determine how straight a LineString is? [duplicate]

I have a bunch of LINESTRINGs and need to classify them based on how strait they are. My idea is to compare the length of the LINESTRING to the distance between the first and last POINTs. I'm ...
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1answer
45 views

Postgis Raster merge geometry

I have a raster table and a geometry table in postgis. My goal is to create a single raster merging elements from both:- WITH geom_raster AS ( SELECT wkb_geometry, ST_AsRaster(wkb_geometry, ...
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3answers
1k views

QGIS, Postgis: Geometry type does not match column type

I'm trying to import some polygon shapefiles to Postgis in QGIS via SPIT. One of them can't be imported and returns this error: ERROR: Geometry type (Polygon) does not match column type ...
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1answer
178 views

how to build and install pgrouting-2.0 on postgresql-9.3 on ubutntu 12.04 Lts precise?

I try to build following instructions from this link https://github.com/pgRouting/pgrouting after downloading from the github. I have done the cmake command and there is my error output: ...
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1answer
748 views

Generating Interactive Tiles using Nodejs, Mapnik, and PostGIS for Leaflet

I am looking to do something like this but where I have all the data on the same server. I've been following through the set of tutorials @ sparkgeo.com/labs/big/ and I'm having some difficulty. ...
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1answer
360 views

How to query OSM for all beaches facing west? - QGIS preferred

I want to identify all beaches on this planet (or a given subset of it) that are facing westwards (+/- 20-30 degrees). My idea is to use OSM as the data source. Extracting all polygons that have the ...
4
votes
1answer
175 views

PostGIS table to network analysis

I use PostGIS 2.0 and Python API (GeoAlchemy) to work with it. I want to convert topological informations (points, lines, faces) from PostGIS tables to topological network (points, lines) to study it ...
2
votes
1answer
94 views

PostgreSQL : how do I make this sum [closed]

I have this huge table with all the addresses of my country in it. Every house is an object, and there is a column for the streetname (or street ID) and a column for the housenumber. I want to make a ...
0
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1answer
60 views

Mapserver openlayer postgis spatial data are in postgis but label I want to display from webservice

My database of spatial data wkb is in postgis and my textual data is in sqlserver now is it possible to show labels through webservice. I have common id in both the database through which I can join ...
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2answers
84 views

QGIS Connection PostGIS and shapefile

I'm working on QGIS with a database created in PostGIS and a shapefile. Inside the database, I have geometry type data about location of some points, instead on the shapefile there some selected ...
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2answers
415 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 ...
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2answers
173 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 | ...
4
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0answers
59 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
28 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?
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2answers
291 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 ...
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1answer
74 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
36 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 ...
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2answers
51 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 ...
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1answer
43 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
65 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 ...
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2answers
65 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
46 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
22 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?
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2answers
137 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?
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1answer
59 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 ...
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2answers
98 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
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1answer
95 views

MS SQL Server 2012 to Postgresql

How to use MS SQL Server 2012 spatial database in postgresql using foreign data wrapper?
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0answers
147 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 ...
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1answer
79 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. ...
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1answer
93 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 ...
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1answer
94 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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0answers
30 views

How to split a polygon by a polygon and apportion attributes - postgis [duplicate]

I would like to split polygons by polygons and have the numerical attributes be apportioned. For example: I have a parcel that needs to be split by region. With How to split polygons with another ...
1
vote
2answers
154 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
vote
1answer
38 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
454 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
62 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
votes
1answer
136 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
207 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 ...
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votes
1answer
60 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 ...
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2answers
60 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: ...
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1answer
29 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
70 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
61 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," ...