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

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1answer
407 views

PostgreSQL / PgRouting syntax error

My question is about Postgres/PgRouting syntax, when I wrote query like this: SELECT * FROM shortest_path('SELECT gid AS id, source::int4 AS source, target::int4 AS target, ...
5
votes
1answer
437 views

Spatial index vs two coordinates indexes

I have a table with two columns: latitude and longitude. I want to get all objects inside a "rectangular" (well, rectangular in a lat/lon coordinate metric) bounding box: min-max latitude and min-max ...
4
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5answers
5k views

What causes this unexpectedly poor GeoServer/PostGIS/OpenLayers performance?

I am having a tough time making this map run smoothly (play around with it for a bit, you'll see). I have taken a few tips from OSGeo's Making Maps Fast document, but I think there's another issue ...
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vote
2answers
6k views

How to install PostGIS shp2pgsql-gui on CentOS 6?

I am installing PostGIS 1.5.3 on a CentOS 6.2 virtual machine to get started web mapping with Geoserver.I have successfully installed PostgreSQL 9.1, PostGIS 1.5.3 and PgAdminIII on the system. ...
3
votes
2answers
863 views

How to use pgRouting's dijkstra_sp_delta_directed with WHERE clause?

Right now I am using PgRouting for vehicle routing and I have problem with Dijkstra shortest path. My query is: SELECT * FROM shortest_path('SELECT gid AS id, source::int4 AS source, ...
9
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3answers
14k views

Converting MultiLinestring to Linestring with PostGIS?

I have a multiline string and want to convert it to a linestring in order to use some functions that only work with linestrings. I used ST_Dump() and got a collection of my geometries. If I merge them ...
0
votes
1answer
278 views

Vertex point is returning None

I have this multilinestring that has 48 NPoints. When I execute ST_PointN(line,5) it returns none. And to continue on, it returns None for everything after index:2 up to index:48. This is how my line ...
6
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3answers
6k views

How to fix performance problem in PostGIS ST_Intersects?

I'm a newbie in postgis and I have a problem in query performance. This my query: SELECT DISTINCT ON (userid) userid ,ST_AsText(position), timestamp FROM table1 WHERE ST_Intersects ( ...
3
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1answer
1k views

How to detect overlapping linestrings in PostGIS?

I'm looking for the fastest way to detect whether a given linestring overlaps another linestring. (As reference, let's say my wife and I both go for a run and take different routes, I'd like to detect ...
2
votes
2answers
1k views

How to add a background map to a java project?

I'm new at GIS. I am trying to make a java application that can display a map with certain points. I have achieved this using the geotools library. However, I want to put the map from OpenStreetMap or ...
1
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1answer
629 views

Passing parameters to PostGIS SQL queries in Python: weird behaviour

The following code always goes to the except section and I do not understand why..Any help would be much appreciated. l = None c = conn.cursor() try: s = "SELECT ST_NPoints(ST_GeomFromText(%s))" ...
5
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2answers
1k views

Exporting PostgreSQL table to FileGDB: wkbUnknown layer geometry type

I'm attempting to export a PostGIS (1.5.3) database table as a File geodatabase using the new FileGDB OGR / GDAL 1.9.0 driver: $ ogr2ogr -overwrite -sql "SELECT * from db_pts LIMIT 1" \ -f ...
4
votes
1answer
1k views

How to assign OGR geometry a spatial reference when writing to a new layer using the Python API?

I'm using the Python OGR API to add new features to a PostGIS layer. However, despite setting the geometry spatial reference, when the geometry is written out the spatial reference is missing. This is ...
9
votes
1answer
9k views

Simple PostGIS ST_Distance query for two points from the same geometry table?

Note: This question was published at Stackoverflow at first. I have a geometry table points_table with SRID 4326 and a few points in it. I need to find a distance between a pair of points (features) ...
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 ...
2
votes
3answers
870 views

How to create a efficent linestring out of geography points using postgis

I'm trying to create a linestring out of geography points. At the moment I'm doing it like this: select ST_GeographyFromText(ST_Makeline(a.record_point)) from ( select (record_point::geometry) from ...
2
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1answer
1k views

JOSM vs QGIS/uDIG for road network editing and storage

My application needs to store a road network and provide editing functionality for that network (editing/updating/removing lanes, signs, traffic lights, speed limits info, etc.). I find JOSM tool to ...
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1answer
1k views

How do PostGIS layers in QGIS work?

I use QGIS 1.4.0 to import a layer which is basically a road network converted from an .osm file to a PostGIS database table by osm2pgrouting. I have skimmed through the documentation, but I am still ...
3
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2answers
1k views

Total great circle distance along a path of points (PostGIS)

I am looking for an SQL query that sums the distances between a series of points using PostGIS. The situation is as follows: I have 2 tables: tracks and points. Points belong to a track and thus ...
2
votes
1answer
481 views

A software architecture for viewing/editing roads and routes

I have a routing software module which uses PostGIS/pgRouting to calculate routes. The road network is generated from an .osm file with osm2pgrouting tool. I need to enhance the functionality of the ...
3
votes
1answer
1k views

clip linestring by length

Is there a way to clip a linestring based on distance? For example, linestring from a to b is 150 meters. I would like to get the linestring from a to a point that is is 75 meters away from a ...
4
votes
2answers
346 views

Postgis Grid Points on Boundary Issue

Hi all hoping someone can help me out with this issue. I've got a table of polygons which are grid squares which get overlayed on a map. These are used when querying data so that points get grouped ...
2
votes
1answer
678 views

The minimum bounding circle of geometry that crosses the 180th meridian

Background: I've been given a task where I have to calculate the minimum bounding circle of Alaska (for the purpose of running a Roeck test). I'm using the Census' state level geometries available ...
5
votes
2answers
759 views

Accessing non-spatial PostgreSQL tables using OGR Python bindings

When connecting to PostgreSQL/PostGIS using the OGR Python bindings is it possible to get non-spatial table names (i.e. OGR layers) from the connection? Currently, doing: conn = ogr.Open("PG: ...
5
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1answer
4k views

How to extract data for a specific area from OSM?

I need to extract all streets available on a particular area of a City. I'm able to extract all streets name using this query: select distinct P2.* from planet_osm_polygon P1, planet_osm_line P2 ...
1
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1answer
911 views

How to Run Ad Hoc Database Queries in Open Jump?

Which plugin allows you to run ad hoc queries from postgis in Openjump? How do you install it in Ubuntu?
2
votes
1answer
334 views

How to import selected features from QGIS to PostGIS?

I am trying to import selected features from Quantum GIS to postgresql directly. I do not know how to do it. Actually, my problem is, I have full country road network. But, I need to cut road network ...
3
votes
3answers
5k views

How to extract latitude/longitude values for specific points from a shapefile?

I have obtained public crash data for the state of Minnesota. I would like to be able to programmatically extract the latitude/longitude of each crash using this data in combination with a series of ...
2
votes
1answer
131 views

Is there a straightforward way to get the source/target point geometry of an edge?

I was wondering if there is a straightforward way to get the source or target point geometry of an edge? It is still not clear to me how the source-target works. For example, if I use ...
11
votes
3answers
1k views

Web mapping software for a huge raster time series?

I'm an ArcGIS Desktop user who is stepping into the world of web mapping for the first time. Following advice I found here on GIS.SE, I started with the free tutorials from OpenGeo. However, I ...
1
vote
1answer
379 views

How to correctly use cursor.execute() with PostGIS?

I do not understand how the operator works some times... Here is an example that works, "SELECT ST_Distance(ST_GeomFromText('POINT(-3.16496271127842 ...
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 ...
1
vote
1answer
380 views

Find all of the ways that intersect a linestring

I'm new to Open Street Map and PostGIS, and am trying to figure out how to find all of the ways that intersect a linestring (i.e. all of the streets that intersect a route). Is there a way to do this ...
2
votes
0answers
421 views

line segments using points

Is there a way to get line segments from a linestring using points with lat/lng coordinates? ST_Line_Substring is taking float8 start/end points. Is there a way to replace the float8 with lat/lng? I ...
2
votes
1answer
556 views

Why does st_split not work?

it seems I am having a problem with ST_Split function. I am trying the following but it does not work. Can anyone spot any problems with the syntax? select ST_Split( ...
2
votes
2answers
264 views

How to remove roads from dataset

I've got a shape file that I loaded into PostGIS that has both road and parcel multipolygons and I need to remove the roads. I tried loading the shp file in qgis and it loads them both as a single ...
2
votes
1answer
3k views

How do I make geoserver update layers and stores?

How do I make geoserver update layers and stores? I've updated the tables in PostGIS used by a data store and layer, but I cannot seem to get it to update. I have the new data running, but I had to ...
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0answers
112 views

Efficiently find points within a great circle corridor [duplicate]

Possible Duplicate: How to efficiently find points within an elliptical area? Using PostGIS 2.0.0 I'd like to filter a table of points down to those that lie along a great circle line ...
10
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2answers
7k views

Is it possible to convert from Geography to Geometry in PostGIS?

I have a shp file that has geography types, Can I convert it with a tool like shp2pgsql? or is there a postgis function to do that?
0
votes
1answer
458 views

Unable to Make PostGIS 2.0 - file not found

I am struggling to get the latest trunk of PostGIS to install on a fresh Mac running Lion. I did install PostGIS 1.5.3-2 for Postgres 9.1 from [KyngChaos Mac OSX Installers][1]. This setup worked ...
4
votes
3answers
560 views

How to efficiently find points within an elliptical area?

Using PostGIS 2.0.0 I need to filter the results of a function, which returns many POINTs, to find the ones that lie within an elliptical area defined by two points and a distance (all parameters ...
1
vote
1answer
154 views

Debugging QuickExport Parameters in Data Interoperability Extension for Exporting to PostgreSQL?

I am using ArcGIS Desktop 10. I tried to configure the QuickExport parameters by examining the log file after I used the QuickExport tool itself. The only things I changed from the log file are the ...
5
votes
1answer
749 views

How to merge linestrings that don't touch based on common name?

I had a table of road line strings that contained duplicate road names with different geoms for different line segments. I extracted the duplicates to another table. I now want to join these segments ...
7
votes
2answers
4k views

Can't import OSM data to PostGIS, permission denied

I use Postgres 9.1 on Xubuntu 11.10. I've created a db 'aus' and user 'aus', granted ALL on the db to the user. Now I try to import the data, and it outputs this error: $ osm2pgsql --create ...
2
votes
1answer
305 views

How to get the Nth LineString from a MultiLineString in PostGIS?

I need a function that gets the Nth LineString from a MultiLineString in PostGIS, somthing like ST_PointN that gets the Nth point from a LineString.
5
votes
1answer
1k views

Split line using line/point in PostGIS 1.5

I have a layer that contains a master line (one big polyline) and a another layer that contains "break lines". I need to be able to split the master line at the intersection of each of these break ...
7
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2answers
2k views

How to run two PostGIS versions in parallel on Windows?

I'm trying to understand how to install PostGIS2.0 on Windows7. The PostGIS site has the following suggestions: PostGIS Experimental Binaries PostGIS 2.0.0SVN Binaries with Raster, Topology ...
5
votes
1answer
546 views

Efficiently querying a region-partitioned PostGIS table

I have two PostGIS tables: one of streets, and one of regions, which, apart from spanning the same spatial extent, are a priori unrelated. The streets queries I perform can be restricted to a given ...
8
votes
3answers
2k views

Dissolve or unsplit lines on common attributes in PostGIS or GRASS?

I have a road centerline shapefile that has roads split at every intersection. However, I would like to join LINESTRINGs that have a common set of attributes into a single LINESTRING. So long as the ...
10
votes
1answer
508 views

How to efficiently find the closest point over the dateline?

I have a PostgreSQL 9.1 table with hundreds of thousands of PostGIS POINTs. For each of these I'd like to find the closest point in another table of POINTs. The points in the second table represent a ...