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

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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
359 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 ...
37
votes
2answers
9k 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
199 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
100 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 ...
13
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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 ...
15
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6answers
17k 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, ...
1
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0answers
829 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
669 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
190 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
605 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
583 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
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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
votes
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
488 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 ...
49
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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
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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
122 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
844 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
687 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
221 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
551 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
307 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 ...
4
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 ...
8
votes
1answer
5k 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
214 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 ...
1
vote
0answers
163 views

How to add column “EDGE” in pgRouting?

I am a newbie in PostGis and pgRouting. I have installed and configured both on my windows PC, following FOSS4G tutorial. I am able to see the result in browser, using GeoServer and OpenLayers. ...
2
votes
1answer
1k views

How to create a PostGIS layer using QGIS API?

I want to create a new PostGIS layer and save changes made to it. Presently, I am connecting Python to PostGIS using psycopg2 but I want to know whether there is any QGIS API function available. ...
7
votes
3answers
4k views

When should I use ST_Buffer?

I would like to know what is the sense of using st_buffer operation. In PostGIS reference guide there is only the syntax and a short description of this operation. Could you give some examples to ...
3
votes
1answer
803 views

postgis compilation error

I'm just having a problem compiling postgis on a second machine, I wonder if anyone has any pointers: ./autogen.sh ./configure gives PostGIS is now configured for i686-pc-linux-gnu ...
2
votes
2answers
464 views

Load multi point shapefiles into postgresql

I am so curious to know how I can change the constraint to accept multipoint when I try to use pgsql to load shap files. I searched a lot, but I could not find the answer. My command line is: ...
2
votes
1answer
281 views

Typecast from circularstring to polygon in postgis

How can i type typecast a CircularString Polygon or Multipolygon in PostGIS? I am doing so because CircularString Datatype is not supported by QGIS and i have to create a circle or ellipse, and it ...
6
votes
1answer
1k views

Geodjango distance between two points appears incorrect

I want to show you something. I am using django+postgis and I am experiencing wrong distance values between two points. This is my model: class Location(models.Model): name = ...
5
votes
2answers
507 views

PostGIS ST_Distance vs. pgRouting

I am looking to create a city directory web app, and the site will need to be able to calculate distances between two geospatial points (like the distance between the user and a restaurant, or the ...
12
votes
2answers
5k views

How to Export Feature GeoJSON from PostGIS

I'd like to do a GeoJSON dump of a PostGIS table, but I want to export features (the geometry and the properties) not just the geometry. I've been digging into the ST_AsGeoJSON function but it looks ...
3
votes
1answer
403 views

Ogr2ogr projection problem- features are shifted 12 miles to the north?

I have discovered a problem related to the output of an ogr2ogr command line call. My resulting polygon features are 12 miles (.18 degrees) due north of where they should be, but the longitude is ...
11
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2answers
6k views

Finding the closest Geometry in PostGIS

I've been looking over the PostGIS "API" of functions, and I notice that most of them take two elements to compare. For example, the ST_Distance function takes two geometry/geography elements to find ...