Questions tagged [postgis]
PostGIS is an extension for the PostgreSQL object-relational database that adds support for geographic objects.
8,199
questions
3
votes
1answer
414 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
6k 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
206 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 ST_StartPoint()...
12
votes
3answers
2k 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
850 views
Using 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 55.9262620593642)'),ST_GeomFromWKB(a.geometry)),...
10
votes
6answers
1k 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
433 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
450 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
842 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(
ST_GeomFromText('LINESTRING(-3....
2
votes
1answer
449 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 ...
4
votes
1answer
6k 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 ...
22
votes
2answers
21k views
Converting from Geography to Geometry data type in PostGIS?
I have a shapefile 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
538 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 ...
5
votes
2answers
801 views
Finding points within elliptical area using PostGIS?
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 (like a great circle line with a buffer around it) ...
1
vote
1answer
186 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 ...
6
votes
1answer
876 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
6k 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
556 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
votes
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 ...
6
votes
1answer
823 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 ...
9
votes
3answers
3k 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
747 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 ...
1
vote
1answer
388 views
Problems with python postgis polygon
I have a problem with the examples in the book "Python Geospatial Development". I can't write to the PostgreSQL database polygons from TM_WORLD_BORDERS (Chapter 7, page 202 in book). Code:
src_file = ...
9
votes
2answers
8k views
PostGIS ST_Buffer Radius Help
I am trying to find all points within a five-mile radius of a given point. I have a query like this:
SELECT * FROM table WHERE ST_Contains(ST_Buffer(geomFromText('POINT(0 0)', 4326), ?), latlon)
I ...
4
votes
2answers
842 views
Why is osm2pgrouting not importing?
I installed pgrouting successfully and did a little import with a 20Mb file. Works good!
Now I'm trying to import a file with the size of a country and it doesn't even start to import. The last 2 ...
6
votes
1answer
1k views
How to sum area of polygons by values occuring in multiple fields?
My data has 2 fields holding landuse types, which both describe what is within the polygon.
For example, the polygon may have Type1=Retail, Type2=Leisure Area= 1
but another polygon has Type1=Leisure, ...
6
votes
3answers
2k views
Getting ST_ClosestPoint for Geography type?
Using PostGIS 2.0.0 I'd like to find the point on a LINESTRING that is closest to a given point. The LINESTRING represents a great circle line (ie. geography type). ST_ClosestPoint appears to do ...
6
votes
1answer
14k views
.NET Entity Framework with PostGIS?
Is it possible to use the .NET Entity Framework with PostGIS?
I've reviewed a few options, including hookup it up with Npgsql using http://npgsql.com/index.php/2009/08/how-to-set-up-entity-framework-...
22
votes
1answer
2k views
What's the status of Postgis 2.0 topology support in QGIS?
Having followed the Postgis developments over the past 6 months I have noticed a bunch of features which seem to be incredibly cool especially in the area of topologies and associating calculations on ...
8
votes
2answers
4k views
Creating a spatial PostGIS table as a result of a PostGIS query
When I want to store the results of a spatial query as another PostGIS table, what should I do? I am interested in identifying all residential buildings that fall within a set of parcels:
CREATE ...
7
votes
2answers
494 views
Memory considerations for cloud based GeoStack
Some time ago I asked about hardware considerations of cloud based GeoStack implementation. As a follow up to this question
There are some good pointers in related question already, but they mainly ...
4
votes
4answers
3k 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
1answer
307 views
How to get all intersecting points to a given area and vice-versa in PostGIS?
I'm developing a project using PostGIS to hold spatial data where I have records that hold geometry point data and records that hold geometry area data. To solve my problem I'm looking for two queries ...
2
votes
0answers
1k views
Arc by center point in PostGIS does not fit the circle
I'd like to store a GML ArcByCenterPoint in PostGIS. I can work out the start, middle and end points required by the CIRCULARSTRING type and all seems to be OK, except that when I visualise the arc it ...
2
votes
1answer
105 views
What's the use of the table extended_geometry_columns in PostGIS
Sometimes my PostGIS database creates a extended_geometry_columns table. After some search i've not found what is the use of this table.
I'm using PostgreSQL 8.4 and PostGIS 1.3.3
This is the ...
6
votes
1answer
8k views
What does “Input geometry has unknown (-1) SRID” mean?
I am trying to run the following query to determine the area and number of points of a polygon:
Select osm_id, st_npoints(the_geom) as numPoints, st_area(transform(the_geom, 3395))/1000000 as areakm2 ...
10
votes
2answers
8k views
Converting PostGIS table to Shapefile in Python?
I want to convert a PostGIS table into a shapefile (without using pgsql2shp).
In order to create a geometry in the shapefile I have to give the Xmin,Ymin and Xmax,Ymax, and the geometry which I have ...
4
votes
3answers
3k views
ST_MakeLine equivalent for CIRCULARSTRING in PostGIS
I'd like to make a CIRCULARSTRING in PostGIS 2.0.0 out of points that are calculated as part of the query (rather than constants). For a LINESTRING I can do this using ST_MakeLine(). Is there an ...
15
votes
3answers
5k views
Join intersecting lines with PostGIS
This is something that I'm almost ashamed to ask but I can't seem to get it to work for the life of me.
I have a road layer with segments, each segment has a Road ID and a segment type.
I would like ...
4
votes
1answer
414 views
Is there equivalent to feature datasets supported by PostGIS?
I am currently planning the migration of a database from ArcSDE/ ArcMap to PostGIS / QGIS.
The data is stored in raster catalogues and feature datasets.
Is there an equivalent to feature datasets ...
8
votes
1answer
9k views
How to import a raster into PostGIS?
I'm trying to follow the instructions here to load a raster into a PostGIS database:
python raster2pgsql.py -s 4269 -I -r *.tif -F myschema.demelevation -o elev.sql
I understand that I replace * ...
9
votes
2answers
2k views
Storing GML surface in PostGIS
I'm using PostGIS 2.0.0 and would like to store a GML Surface in a way that allows calculating intersections between that surface and various points and lines. In my case, the Surface will have one ...
11
votes
3answers
5k 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 ...
3
votes
1answer
721 views
How to show one to many relationships in GML from GeoServer/PostGIS?
I am just figuring out how to use GeoServer and PostGIS. I am using the States.shp example that came with GeoServer, and I have uploaded that into a table into the PostGIS database. I have created a ...
10
votes
1answer
1k views
Can you query overlapping user-defined polygons at a given point in Google Maps?
I need to find out the limitation of working with the Google Maps API, and the possible solutions for doing semi-complex spatial comparisons.
What I'm looking to achieve is a system of comparison ...
3
votes
2answers
519 views
How to recalculate the the length of a geography linestring from nearby geography point in POSTGIS?
I have a geography type linestring
*route_geography geography(LineString,4326)*, its a route from point A to point B. Now I have a point C near that line. I want to find the nearest point on that line,...
71
votes
7answers
27k views
Creating regular polygon grid in PostGIS
How to create, on the shape of a polygon, a regular grid of polygons/squares of an given size, in PostGIS?
I have thought about a function like Creating regular point grid inside polygon in PostGIS ...
24
votes
5answers
5k views
Alternatives to ogr2ogr for loading large GeoJson file(s) to PostGIS
I have a 7GB GeoJson file that I would like to load into a PostGIS database. I have tried using ogr2ogr but it fails because the file is too big for ogr2ogr to load into memory and then process.
...
1
vote
1answer
276 views
How to solve “Error creating GEOS Coordinate Sequence” in Postgis?
When I run this query:
TRUNCATE sertaozinho.apps;
INSERT INTO sertaozinho.apps (id,tipo,the_geom)
VALUES (DEFAULT, 'app' ,(
SELECT st_union(
CASE
WHEN area.cobertura = 'lago' THEN ...
