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

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0answers
623 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
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1answer
95 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 ...
5
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1answer
4k 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 ...
5
votes
2answers
4k views

How to convert 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 ...
2
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3answers
1k 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 ...
7
votes
3answers
2k 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
270 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 ...
6
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1answer
5k 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
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2answers
1k 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 ...
6
votes
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 ...
3
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1answer
333 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
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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
351 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 ...
35
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2answers
8k views

How to create a 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 Create regular point grid in Postgis only for squares, ...
11
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4answers
2k 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. ...
0
votes
1answer
196 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 ...
3
votes
2answers
2k views

ST_Distance versus ST_Distance_Spheroid?

As my client software uses lat/lon coordinates when communicating with my (spherical mercator) postgis database i decided to ST_Transform every geometry to WGS-84. However i noticed that ST_Distance ...
0
votes
1answer
98 views

How to query distict row with the same label from different linestring with multiple segment?

I have a multilinestring street table in postgis with two columns: label and prefix. This table has 2 different roads with the same name and each road contains multiple segments. Roads were splitted ...
12
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1answer
1k views

Is there a PostGIS function for determining whether a linestring intersects itself?

I've been looking for a function that can tell me if a LineString intersects itself. I've tried calling st_intersects with the same LineString twice, but obviously identical linestrings will ...
14
votes
6answers
16k 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 ...
5
votes
1answer
1k views

How to route over (partial) edges in pgrouting?

I have made a route planning system (based on shortest path using A*) like the Google directions service using pgrouting and google maps. It includes clicking on the map to generate waypoints, ...
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0answers
807 views

Cannot Display Data From POSTGIS

I try to display the data that I have converted shp into PostGIS database with MapServer and OpenLayers. When I try to show directly shp file is successfully displayed in OpenLayers, but when I try to ...
1
vote
1answer
1k views

Mapserver/PostGIS Query Error

I'm having some difficulty understanding the error I am getting from my mapserver/postgis program. I have the following map file: MAP # start of map file NAME "sample" EXTENT ...
2
votes
1answer
4k views

Basic MapServer query of PostgreSQL/PostGIS database

I've just installed MapServer on a linux server and I am trying to understand how to display a basic map using a PostGIS database. I have displayed a shapefile in the browser, so I know that the ...
11
votes
1answer
658 views

Nearest Neighbor Grouped Selection in QGIS

OK - so I have an interesting problem I am trying to solve. I have a list containing over 100,000 points in lat/long format which I have imported into qgis. Now, what I am trying to do here is group ...
6
votes
1answer
189 views

How to install a patch in PostGIS

Can anybody tell me how to install this patch in PostGIS? http://trac.osgeo.org/postgis/ticket/413 http://trac.osgeo.org/postgis/changeset/7534 I need to use the ST_OffsetCurve function. but it ...
2
votes
2answers
571 views

unable to call shp2pgsql using python

I am unable to call shp2pgsql using python as I have to pass various options like (-s -a -i) and I am not getting the required output .. Method I am using is p1 = subprocess.Popen(["cmd", "/C", ...
6
votes
2answers
563 views

PostGIS: Approximating a house number from address range

I'm developing a reverse-geocoder for Canada. So far, given a lat/lng, I can find the nearest street (line segment), which includes line segment direction and address ranges for both sides of the ...
6
votes
5answers
6k views

How to load Shapefiles into a remote PostGIS db using command line?

Can we import a Shapefile from a system which doesn't have PostgreSQL installed (client machine) into a system having PostGIS installed? I am getting problem with 'shp2pgsql' and 'psql' since both ...
5
votes
1answer
1k views

How to create a routable road network from Ordnance Survey data?

I've been following the "Beginners Guide to pgRouting" in an attempt to create an in-house application that provides drive-time isochrones. I have a server, postgreSQL and PostGIS and pgRouting - no ...
8
votes
4answers
2k views

Rename postGIS table and updating the GeoServer?

I want to rename one of my postGIS tables. However, when I do this by applying a simple ALTER TABLE old_name RENAME TO new_name; The spatial data, as I understand it, isn't updated with the new ...
11
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4answers
2k views

Options for displaying PostGIS rasters in OpenLayers

This question is similar to an earlier question about displaying vector data in a web-map. I want to have a basic web interface which uses OpenLayers and can display raster data that is currently in ...
5
votes
2answers
478 views

ArcMap Draw Camera Range with ArcPy

i am working on some camera data. I have some points which consist of azimuth, angle, distance, and of course coordinate field attributes. In arcmap I want to draw shapes like this: The shape is ...
8
votes
1answer
3k views

Ring Self-Intersections in PostGIS

This is a follow on from previous question. You will see I am a new PostGIS user. I have looked at the validity of the topology in my data and find around 1700 topology issues in the landcover ...
48
votes
8answers
10k views

How to create Vector Polygons at the same amazing speeds GISCloud is able to render them?

EDIT (outlining new bounty added): I have added the largest bounty possible to this question in hope of getting a very detailed answer. Your solution should outline a step-by-step guide utilizing open ...
6
votes
1answer
1k views

PostGIS and invalid SRIDs

I'm having difficulty with a PostGIS query. I am trying to query my database (world_countries) using a bounding box drawn on a google web map. The objective of this query is to find any countries that ...
8
votes
1answer
121 views

How to rectify the walls of buildings in PostGIS?

I need an operations in PostGIS to eliminate intermediate vertexes in a polygon to rectify the walls of a building. I was revising http://trac.osgeo.org/postgis/wiki/UsersWikiExamplesSpikeRemover but ...
7
votes
1answer
822 views

PostGIS Intersection and Summarise Attributes

I am usually an ArcGIS desktop user, but keen to start using PostGIS more and I have a really big bit of processing to do. Not sure what functions to use, hopefully someone can help. I have a polygon ...
4
votes
2answers
663 views

Merge reversed linestring in correct order in postGIS

I want to merge linestring in the correct order in postGIS, but sometime they are reversed so something like this : select astext(linemerge(ST_union( ST_GeomFromText('LINESTRING(3 3, 2 2)'), ...
2
votes
1answer
218 views

Best way to exclude 0,0 from geography results (PostGIS, GeoDjango)

Using PostGis and GeoDjango with a model having a Geography field I'm trying to exclude results where the location is 0,0. I get the error PostGIS geography does not support the "exact" lookup. The ...
9
votes
1answer
534 views

How should I manage PostGIS Raster data with different projections?

I have a requirement to store and manage archaeological geophysics data that is collected as a rectangular array of samples -- a raster image. Each raster will usually 20x20 or 30x30 floating-point ...
2
votes
1answer
299 views

How to modify area polygon in postgres? [duplicate]

Possible Duplicate: Automated correction of parcel geometry based on area measure I need a function to modify area polygon in postgres the major probleme is automated correction of parcel ...
3
votes
2answers
2k views

Setting up WMS with PostGIS, MapServer and Apache

I am trying to setup a web map service (WMS) for rendering a few shape files that I have stored in a PostGIS database. I decided to use MapServer for rendering engine and has installed it on my Ubuntu ...
3
votes
3answers
3k views

Inserting polygon centroids into an additional column in PostGIS

I'm trying to calculate the x and y centroids for a table using ST_Centroid. The documentation says that it returns the geometric center of a geometry. I first made a column X: ALTER TABLE ...
7
votes
1answer
4k views

How to retrieve the corners of the bounding box from ST_Extent?

Is there any way to fetch the lat/long of the corners of the bounding box we got from ST_Extent? select ST_Extent(geom) from tableName;
11
votes
2answers
2k views

PostGIS raster value of a lat/lon point

I have a tiff raster in my PostGIS 2.0 database. I want to get the value of the raster at a specified lat/lon point. I have: postgresql-9.1 postgis-2.0-svn with raster support a raster imported ...
5
votes
2answers
2k views

How to export a PostGIS raster to PNG?

I have a raster which is split into 30 tiles and I want to dump them all into PNGs. I've read the documentation http://postgis.net/docs/RT_ST_AsPNG.html but still don't know how to dump it well. If ...
8
votes
3answers
6k views

Bounding box for PostGIS table

Is there an easy way to get the bounding box for an entire table in PostGIS? Thanks
13
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1answer
2k views

Identifying topological relationships using PostGIS

I'm trying to perform a basic typology analysis using PostGIS. My objective is to find any polygons that touch other polygons. To do this, I thought the ST_GetFaceEdges would work (reference). I want ...
2
votes
1answer
213 views

Automated correction of parcel geometry based on area measure?

i have a set of parcels in DWG file and i have the areas that should be in these parcels in an excel file, so i have to modify each parcel to match the area specified in the excel file with a moving ...