Tagged Questions

1
vote
1answer
43 views

How do I convert MultiLines to MultiPolygons using Postgis

In postgis I'm using the following query to buffer lines to polygons: UPDATE rivers SET poly = ST_Multi(ST_Buffer(lines, 0.01)) where id = 1; The column 'lines' is a MultiLine and the column ...
1
vote
0answers
29 views

Joining layers with respective elements with PostGIS Topology

Recently I have started using PostGIS topology extension, but I have some difficulties in understanding how the structure works: One of the key points is the use of "layer"s: as of what I understand, ...
3
votes
0answers
60 views

How to install PostGis on EC2 micro-instance

I tried to install PostGIS on my Amazon EC2 microinstance using sudo yum install postgis2 and got following error message: $ sudo yum install postgis2 Loaded plugins: ...
2
votes
1answer
62 views

Calculating points in the USDA's Cropland Data Layer coordinate system

I need to integrate against the USDA's cropland data layer. They've got a demo and some API docs. The important query I need to run is this, given an (x, y) of say (1551459.363, 1909201.537): ...
3
votes
1answer
37 views

How can I check if a multipolygon can be represented as a simple polygon?

I have a large (30m+ records) spatial data set I have imported into a PostGIS database. I did not expect to find multipolygons in the data set, but it does have a few of them. I'd like to take a ...
2
votes
2answers
107 views

PostGIS: Convert meters to arbitrary spatial reference units?

I'm writing a query that needs to be able to work with data of any SRID. The basic problem is very simple - I get two pieces of information: A point (SRID = 900913) A distance (unit = meters) I ...
0
votes
0answers
35 views

tinyows failing to connect to postgresql - Ident authentication failed for user “postgres”

I'm getting the above error on a new and local tinyows installation on Centos 6. Postgresql 9.2, PostGIS 2.0. I can connect to PostGreSQL locally and from my LAN using several other methods (psql, ...
2
votes
1answer
68 views

Cannot find my schemas in QGIS's “Add PostGIS layers”

When I connect to my PostGIS database using QGIS's Add PostGIS Layers, I see only public topology pg_catalog information_schema My other schemas that I have created are not shown here. Anyone else ...
0
votes
1answer
89 views

How to split line layer at polygons' boundary of a polygon layer?

I have a line layer and a polygon layer in PostgreSQL 9.2, PostGIS 2.0. How can I split every line each time it crosses a polygon's boundary?
3
votes
1answer
43 views

PostGIS: Merge multiple table with same GID

I just imported some shapefiles with the PostGIS importer. Because several errors and issues I had to split my shapefile in multiple parts. Then I imported them one by one. I thought I can easily ...
2
votes
1answer
89 views

PostGIS ST_Contains question

Here's a quick summary about what I'm trying to do: Let's say I got two layers. One (A) with 10 polygons and one that is more granular with 100 polygons (B). Just to check if the behavior of PostGIS ...
2
votes
1answer
119 views

How to import ECW into my postgis database with raster2pgsql (windows)

I'm working on windows 7 64 bits, postgis 2.01. I have to import ECW files into my postgis database. Unfortunatly, my postgis seems to has been compiled without gdal ecw support.When i do a ...
2
votes
1answer
130 views

generate height data from DTED maps

I have 16 DTED maps of (1 degree x 1 degree). I have to generate combined height matrix of maximum 4 (1 degree x 1 degree) DTED maps in my C++ application. Can someone suggest to me which open source ...
1
vote
0answers
65 views

Renaming Columns in Geotools FeatureType

I am attempting to build a simple java program that loads shapefiles into a Postgis 2.0 database. Everything is working out great except that I would like to be able to modify the FeatureType in the ...
3
votes
2answers
272 views

PostGIS - incorrect result distance between two points

I am quite confused the way PostGIS is returning the result for this basic query. So I am trying to find the distance between two points 45.2714,71.2087 and 42.3739,66.39 and the distance should be ...
3
votes
1answer
134 views

Using PostGIS for a large trajectory dataset

I have a spatial trajectory dataset which basically contains about 10E6 (lat,lon,time)-tuples, grouped together by an identifier so they form trajectories. Currently, SQLite is used to store the raw ...
6
votes
2answers
266 views

PostGIS SQL query to find a polygon that intersects with a line

I need to build a PostGIS query that would select every polygon inside an area the river is flowing through. I'd better describe with an example below: There is a river (blue line) flowing through ...
7
votes
2answers
164 views

How to get distance between one point and all other points in a table?

I have a table in Postgres with lat and long columns. Can I use the ST_Distance_Sphere or ST_Distance_Spheroid methods to get the distance between one point and all other points in the table? Do I ...
7
votes
1answer
249 views

How to set up GeoDjango with PostGIS 2.0?

I would like to run GeoDjango (Django 1.4) with Postgis 2.0. Whenever I try to run syncdb I get the following error for geographic fields: Failed to install index for stores.Store model: operator ...
1
vote
1answer
203 views

How to find the nearest line from a point?

I have a table of Roads in PostGIS which geometry is "geometry(MultiLineString,4326)". Its attribute are gid osm_id name ref type oneway bridge maxspeed geom Now i want to know ...
2
votes
1answer
114 views

How to fix 'GEOSDifference: TopologyException'?

Why does Postgis throws an error in this SQL? Error: ERROR: GEOSDifference: TopologyException: found non-noded intersection between LINESTRING (-5.67027 43.5374, -5.67085 43.5376) and LINESTRING ...
2
votes
1answer
164 views

Querying PostGIS Raster with MultiPoint

For one of my projects using PostGIS 2 I have a table with GPS tracks (igc_files). It holds records including a MULTIPOINT() column that has about 1,000 points for each record and a column that has an ...
2
votes
2answers
185 views

What's the fastest way to search for polygons that intersect with others?

I'm querying the database for searching polygons that intersect with others, but is very slow research, wanted to increase the speed. I thought of using sphinx, solr, elastic search googled but did ...
2
votes
1answer
252 views

How to find polygons inside polygon with PostGIS 2.0

I have a relation representing all the counties in my country and the other one containing all the districts - e. g. each and every county is composed of several districts. How do I select them with ...
4
votes
1answer
118 views

Update PostGIS after updating GDAL?

I am using PostGIS 2.0 and I want to use the raster functionality through mapserver. It seems as if the latest official GDAL release 1.9.1 has an unstable PostGIS raster driver, as pointed out in a ...
-1
votes
1answer
130 views

PostGIS raster support

I have the following requirements to manage raster data 1) Convert raster-maps from BSB format to PNG or GeoTIFF 2) Cut the borders of the map 3) Merge individual maps to form a contiguous coverage ...
2
votes
1answer
317 views

Access PostGIS Raster layer through mapserver

I am trying to use a cgi script calling mapserver to display a raster layer that is stored in a PostGIS database. However, only a blank white image is returned and I don't know where the problem is. ...
5
votes
5answers
737 views

How to split OSM roads into individual segments at intersections?

I want to create a road-network for use with pgRouting using OpenStreetMap data. I loaded a shapefile from GeoFabrik into a Postgres table (with PostGIS enabled). However, one problem I had was that ...
1
vote
2answers
98 views

st_intersection; What Im doing wrong?

Im trying to run this query : create TABLE data.agri_grc as select id, code_00, ST_Intersection(data.agri.geom,data.grc_bor.geom) as geom from data.agri; But im getting this error: ERROR: missing ...
0
votes
1answer
630 views

How to export data from QGIS to display in Google Maps?

I'm exporting layers of a project for a quantum gis postgis table and visualizing the data in gmaps, but the coordinates are very wrong. is there any special way to export the quantum gis? postgres ...
-2
votes
1answer
174 views

Postgis error on select all intersetcs of a polygon [closed]

i can get all polygon on intersects this:-7.9245860488441 -37.122384500713,-7.9245860488441 -37.11904223938,-7.9233955716106 -37.1187601948 SELECT * FROM propriedades WHERE ST_Intersects( ...
3
votes
1answer
166 views

How can I find the nearest points (plural) on a line segment using PostGIS

I'm locating the nearest point on a line segment with PostGIS and ST_ClosestPoint, I can select the point on each of these line segments which is closest to the starting point. Which looks something ...
1
vote
1answer
287 views

Importing planet files into Nominatim

After a gruesome night installing PostgreSQL 9.1, PostGIS 2 and Nominatim 2 on CentOS 6.3 using the instructions here, I am finally at the stage of importing a US planet file. Problem: In ...
-5
votes
1answer
163 views

How to create,store and retrieve the spatial data in postgresql [closed]

i am new to postgresql/postgis can anyone explain in steps about how to store the spatial data and retrieve the spatial data and visualise in map in a proper steps.. pls . its very urgent..
2
votes
1answer
272 views

Error creating a spatial database. ERROR : could not load library “/usr/pgsql-9.1/lib/rtpostgis-2.0.so”

I am running PostgreSQL 9.1 with Postgis 2.0 on Fedora 15. When trying to install the raster support, psql -d mydb -f rtpostgis.sql -v ON_ERROR_STOP=1 I get the following error ...
2
votes
1answer
595 views

How to find the nearest point by using PostGIS function?

table A: lat | long | the_geom | code | sign 13.8433095 | 100.6360357 | 0101000020E61.... | ABC | start_point 13.7544738 | 100.5459646 | 0101000020E6..... | ABC | end_point 13.4124215 | 100.6232332 ...
0
votes
1answer
41 views

Can I use in a postgis db within the same table a combination of CRS?

I'm experimenting around with my postgis2.0 database. I want to create a basic table to store all my point data and in the process,I realized that the coordinates are in different CRSs. So naturally ...
3
votes
1answer
125 views

How to Load RDF Data to PostGIS?

I want to load some sample RDF (Relational Data Format) to POSTGIS. Are there any tools or methods to do this.
8
votes
2answers
171 views

Moving existing hard drive with PostGIS data directory to a new computer

I have a new computer that is replacing an old machine that has PostGIS installed. The old computer has a 2nd hard drive where the PostGIS data directory is stored. I want to move this drive over to ...
1
vote
0answers
56 views

Make a thumbnail of a raster in PostGIS

I'm fiddling around trying to create a thumbnail of a fairly large (originally 27MB) raster, chunked into 64x64 blocks. I've got the following and it works, quite well, but I'm wondering if there is a ...
3
votes
1answer
192 views

gdalinfo gives no georeferencing information for a PostGIS raster

I have a PostGIS raster dataset which I am trying to access via GDAL. I've had various problems with making this work, so thought I'd try running the gdalinfo command to check that GDAL can actually ...
3
votes
1answer
338 views

PostGIS 2.0 ST_Transform with Rasters cannot find custom SRID

I'm trying to calculate an average value in a buffer around a point. Given a raster in EPSG 4326 and a similar point, this is fine, except that the values will be skewed as they are not projected in ...
6
votes
1answer
2k views

PostGIS - 1.5 to 2.0 easy update

I have a PostGIS 1.5 database and want to update to 2.0. I read that because this is major release I have to follow the 'Hard update' procedure. However the spatial data I have is only test data so I ...
3
votes
1answer
378 views

remove duplicate points based on a specified distance

i have a table of points with each point acquired on a specified date, by a specified source, and having a measured value. i want to consider points as duplicates if they have the same date and if ...
5
votes
1answer
445 views

Speed up pgRouting point_to_id using new <-> operator in PostGIS 2.0.0

The point_to_id function, which assigns a node id to a point based on existing nodes and tolerance, is using a query as follows: SELECT id, the_geom FROM vertices_tmp WHERE ...
16
votes
1answer
1k views

Comparison of geocoding solutions (such as Gisgraphy & PostGIS 2.0)

As I am sure many of you are aware, PostGIS has finally released Version 2.0 and included within this version they have also built a geocoder (see: http://postgis.refractions.net/docs/Extras.html). ...
0
votes
1answer
302 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 ...
7
votes
2answers
983 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 ...