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

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psycopg2 error with QGIS 1.5

So I just installed QGIS 1.5 using the windows installer not the osgeo4w one and now any plugins that need access to PostgreSQL databases don't seem to work, they all throw a: "Couldn't import Python ...
9
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1answer
3k views

How to perform a spatial join of point and polygon layers in PostGIS?

I have a point dataset representing households that I want to associate with a parcel layer (i.e. assign its parcel_id). With ArcMap, I could spatially join the polygons to the points and specify that ...
8
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2answers
508 views

Clarification of the “25D” option in ogr2ogr

[EDIT: In my original post, I had received an error that was based on a typo, so I scrapped that part of the question, but left the questions that still apply.] In the ogr2ogr docs it says: -nlt ...
7
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1answer
1k views

How is ST_PointOnSurface calculated?

The PostGIS documentation states that ST_PointOnSurface returns "a POINT guaranteed to lie on the surface". It seems like this function could be trivially implemented to give results that satisfy the ...
5
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1answer
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How to Import ESRI Geodatabase format .gdb into PostGIS

I ran into a problem when loading a ESRI Geodatabase format .gdb into PostGIS. I have data 2.5GB GDB file. I followed some tutorials on the internet, but it seems that doesn't work out. I created a ...
5
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1answer
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Install PostGIS on Ubuntu 12.04

I am trying to install PostGIS on Ubuntu 12.04 and I think everything is installed correctly except for postgresql. I followed this post. I get the following error and nothing I do seems to satisfy ...
3
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2answers
1k views

QGIS DB manager Import layer/file tool won't allow me to choose “Append data to table”

I want to append some data to a layer in my PostGIS DB using a shapefile, but when I use the Import layer/file tool in QGIS, it doesn't allow me to choose the append option. Why is this and how do I ...
3
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2answers
4k views

How do I use st_dwithin with meters?

I am trying to follow PostGIS ST_Buffer Radius Help to use a 50 meter distance but postgis is returning an error. I am trying the following SQL, SELECT id FROM table WHERE ...
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1answer
300 views

pgrouting unexpected output

Thats my ways.shp file. I loaded this to PostgreSQL DB using PostGIS shape file loader. I ran pgr_anlayzeGraph() on it and found it had a lot of isolated segments. Next I ran pgr_nodeNetwork() to ...
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2answers
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ST_DWithin uses Geometry or Geography type

assuming I use the following query to match the locations to a poi within 10km distance: SELECT poi.poi_id, h.loc_id, (ST_Distance(poi.geom,h.geom)*111.111) as distanceinkm FROM iut_poi_transl AS ...
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1answer
127 views

Is it possible to access geoserver wfs layer from localhost:8080 in to web application? [closed]

I want to add a WFS layer. I am trying to get WFS layer from localhost:8080 geoserver. but I am getting eoserver DateLineWrap in Openlayers.js file...
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6answers
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Spatial databases learning resources for newbies

Would be taking up a course on spatial databases next semester. Would anybody know a newbie friendly introductory resource? A vendor neutral one would be preferable. Thanks.
8
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2answers
5k views

Implementing Spatial Autocorrelation using QGIS or PostgreSQL or any other free application?

I am a total newbie on the GIS scene so I hope this is not a stupid question. I have two layers in a PostgreSQL database. The first layer contains points where events happened in Europe. The second ...
18
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2answers
7k views

How can I find a point inside a polygon in PostGIS?

How can I find a point that is guaranteed to be within a given polygon in PostGIS? I am aware of the ST_Centroid function. However, the centroid is not always within a polygon, see below: ...
12
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1answer
2k views

Open-source GIS implementation of the Huff model

This might be a stretch, but I was wondering if anyone implemented gravity modeling tools or scripts for Retail Market Analysis (like the Huff Model), to analyze spatial data for customer-store ...
28
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4answers
25k views

Why does PostGIS installation not create a template_postgis

I went this route for installation of PostgreSQL and PostGIS: PostgreSQL using the standalone KyngChaos, PostGIS install from KyngChaos as well... pgAdmin3 from PostgreSQL Tools Now when I launch ...
14
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2answers
3k views

How to calculate the angle at which two lines intersect in PostGIS?

I want to calculate the angle between two lines where they intersect in PostGIS. The starting point for angle calculations in PostGIS seems to be ST_Azimuth - but that takes points as input. My first ...
12
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3answers
3k views

Optimizing a nearest neighbor calculation using PostGIS

I'm using PostGIS to calculate the nearest neighbors of polygons. What I want to calculate is the minimum distance from each polygon, to the nearest polygon. Thus far I have got great help from Mike ...
9
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1answer
2k views

One to Many Relationship in QGIS with PostGIS

Does anyone know of any tool that can do a One-to-Many relationship in QGIS. I have my data in a PostGIS database. I would like to be able to query spatial layers that are related to spatial or non ...
18
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5answers
2k views

How to simplify a routable network?

I have a network graph that I need to simplify in the sense of reducing the number of edges. The idea would be to merge nodes that are located close together and remove the connecting short edges. ...
15
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7answers
18k views

How can I enable Shapefile GUI Loader in pgadmin3?

I have installed PostgreSQL 9.1 with PostGIS 1.5.3 on Ubuntu 11.10. I also installed pgadmin3 1.14.0-beta1, following this instructions. If I remember correctly, when I installed PostGIS on Windows ...
14
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2answers
16k views

Adding shapefiles to PostGIS database

I was able to create a Postgresql database and then I executed, createlang plpgsql geospecies psql -d geospecies -f postgis.sql psql -d geospecies -f spatial_ref_sys.sql So now can I directly ...
32
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2answers
2k views

What coordinate system should be used to store geography data for celestial coordinates?

I am doing an astronomy project. I want to have the information about our images stored in a spatially enabled database. This, I would think, should be a very easy special case for GIS functions ...
27
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3answers
5k views

Meaning of Simplify's tolerance parameter

The standard parameters of Douglas-Peucker's simplify algorithm are geometry and tolerance (e.g ST_Simplify in PostGIS). What's the meaning of the tolerance parameter? I know that the bigger the ...
6
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1answer
792 views

calculate slope for a road network

I am working on a road network for routing operations using postgis and QGIS. I am new to both of these tools and need to calculate the slope for each edge (by retrieving the Z value for the start ...
6
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1answer
676 views

Filling a polygon with lines using Postgis

i need to calculate a specific distance in an area. The distance is calculated from parallel lines in a polygon, And i need to find out how many parallel lines (with x meters distance to each other) ...
3
votes
2answers
817 views

Finding points along a path

I am unsure of the best approach to this problem. I can think of some ways of doing it which I will list below but I am looking for the best and most efficient way of doing this. Problem Given a ...
3
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1answer
3k views

How to find the nearest point projected on the road network?

I would like to know if there is a function at pgRouting that given a point (lon/lat) can give you the projection of that point to the road network . Thanks in advance john
13
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2answers
675 views

What is the best hack for importing large datasets into PostGIS?

I have to import large Shapefiles (> 1 million records) into PostGIS, and I have been wondering about the best way to do it. In my question I used the word "hack", instead of tool, on purpose ...
12
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5answers
1k views

Large shapefile to raster

I have a large shapefile (1 gb) and need to rasterise it. I have tried the following already. 1.) Import it into GRASS using v.in.ogr this failed with the error message: ERROR: G_realloc: unable to ...
8
votes
1answer
7k views

How to create a table from existing tables (applying new schemas) in postgis DB?

I have a table that is geospatially enabled; that contain world borders. I want to break it down to different schemas (global, europe etc..) . My thought is to use use something that looks like this: ...
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1answer
2k views

What is a “non-noded intersection”?

Can someone provide a precise definition of what a "non-noded intersection" is? There are various GIS platforms and toolkits that have errors with this text, and Google search results for this tend to ...
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2answers
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Using OpenLayers (with OpenStreetMaps) and PostGis for rendering data acquired from GPS tracking device?

I'm researching and planing to acquire data from GPS device and store them in postGIS database, then use geodjango to process/work them out and finally chart them on a map with OpenLayers. Will these ...
7
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3answers
2k views

Point in polygon algorithm for multiple polygons

I've a Google map with bunch of polygons on it. Here is a problem I'm interested in: Given a lat,lng point, what's the best way to determine all the polygons that this point lies in? The obvious way ...
10
votes
5answers
616 views

Database versus Files for Solo Developer

I'm just getting started in GIS and am interested in using it to create maps of mountain biking trails in my area and nearby. I've been learning QGIS and have made enough progress to generate a decent ...
8
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2answers
735 views

PostGIS Union Between Two Tables, Preserving Attributes

I'm trying to union US State level upper- and lower-level government boundaries in such a way that generates one PostGIS table with both the upper and lower level names for each shape. In my example ...
8
votes
3answers
1k views

Retrieve polygon smallest MBR

I have a postgis table containing polygons. I want to transform my polygons to 4 points polygons : retrieve the smallest MBR. Here comes an illustration of what I want : My original polygon is ...
7
votes
3answers
626 views

Is there a paid service for accessing a PostGIS/OSM DB

I want to render a world map with mapnik and postgis, but do not want to set up my own DB, because the needed hardware and processing time for the OSM import make it nearly impossible for me. I just ...
7
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2answers
2k views

Difference between two layers in PostGIS

What is the right way to calculate the difference between two layers? I tried to use the following approach: SELECT ST_Difference(river.geom, lakes.geom) FROM river LEFT JOIN lakes ON ...
6
votes
3answers
4k views

PostGIS non functional on Ubuntu 14.04

I am unable to create the PostGIS extension on new databases in Ubuntu 14.04: $ psql pg_testing -c "create extension postgis" ERROR: could not load library ...
6
votes
2answers
2k views

Storing GPS tracks with timestamps in PostGIS

I need to store a series of GPS points with timestamps in the database (traces of various vehicles). I am wondering which of two approaches to choose for storing them in the PostGIS table: 1.) Each ...
5
votes
2answers
707 views

How to add sfcgal to an already postgis enabled database

I have a postgres 9.1 database with postgis 2.1, and I recently needed to add sfcgal to it, so i rebuilt postgis 2.1, but I can't find out how to update the postgis extension in postgres without ...
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votes
4answers
1k views

GeoServer Layer from PostGIS not updating

I created a WMS layer from a PostGIS table with a fraction of total polygons in GeoServer. Everything displayed fine. Then, I added the rest of the polygons to the table in postgis. For some reason ...
3
votes
3answers
4k views

Connnect to PostGIS db using QGIS - when not on localhost

I"m just getting started with PostgreSQL/PostGIS db (v9.2) and I'm wanting to connect to db while not on the localhost using QGIS. I've been able to connect successfully on localhost, however I'm not ...
2
votes
3answers
3k views

Render vectors from OSM data in POSTGIS database

I'm a newbie when it comes to mapping application. I had successfully loaded my OpenstreetMap data in a Postgresql/PostGIS database. Now my problem is how to render the vector data (the POI's, ways, ...
7
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2answers
3k views

SQL query to have a complete geojson feature from PostGIS

I would like to get a geojson feature with properties from PostGIS. I have found an example to have a feature collection but I can't make it works for just a feature. so far I tryed to modify the ...
7
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0answers
3k views

Loading raster from PostGIS DB into QGIS: succeeded yesterday, fails now [closed]

I have a PostgreSQL(v.9.2)/Postgis(v.2.0.3) database which includes raster layers (added through raster2pgsql). To open them in QGIS (v.1.8.0-Lisboa), the "Add Postgis layer" menu will not work; ...
7
votes
4answers
690 views

Is there a way to identify and remove similar GPS tracks in PostGIS or ArcGIS?

I have a large number of GPS tracks from a number of different users. I'd like to identify tracks that take the same route and remove those duplicates. For example, a user takes the same streets from ...
6
votes
3answers
4k views

PostGIS: parse geometry wkb with OGR

I'm trying to pull a LineString geometry out of PostGIS and parse it with OGR (python bindinds). from osgeo import ogr import psycopg2 connection = psycopg2.connect("...") cursor = ...
5
votes
3answers
2k views

Loading raster data to postgis

I'm a newbie in GIS technology and need some help in loading a rainfall radar raster data into PostGIS. The raster image is shown here: What I need is to store in the database the radar ...