PostGIS is an extension for the PostgreSQL object-relational database that adds support for geographic objects.
15
votes
5answers
2k views
How do you best deal with data that spreads across UTM Zones?
I have data that spreads across two UTM Zones GDA/MGA94 UTM Zone 55 and 56. I have layers such as a cadastre, roads, pipelines etc where I want to store measurements like lengths and areas in metres ...
10
votes
3answers
854 views
How to interpolate GPS Positions in PostGIS
I have a PostGIS table of GPS positions for every five seconds:
2011-01-01 00:00:05, POINT(x1,y1)
2011-01-01 00:00:10, POINT(x2,y2)
2011-01-01 00:00:15, POINT(x3,y3)
...
I'm looking for a query ...
6
votes
3answers
616 views
Retrieve polygon smallest MBR
I have a postgis table containing polygons. I want to transform my polygons to 4 points polygons : retrieve the smallest MBR.
Here comes an illustration of what I want :
My original polygon is ...
5
votes
3answers
93 views
How to insert a GeoJSON polygon into a PostGIS table?
I need to insert a polygon from GeoJSON to my PostGIS table. This is how the SQL query looks like.
INSERT INTO tablename (name, polygon)
VALUES
(
'Name',
ST_GeomFromGeoJSON
(
{
...
4
votes
3answers
3k views
Select bounding box using postgis
I want to create a query to select all ways and their nodes that exist within a bounding box using postGIS. The bounding box shall includes all details as osmosis "--bounding-box" command will ...
4
votes
3answers
1k views
Newbie PostGIS Geometry and Multilinestring Clarification
I'm having some trouble figuring out if I've got the right data loaded for PgRouting.
Using the bash script included in PostGIS 2.0, I loaded Tiger2010 data for U.S. State California.
The edges ...
3
votes
2answers
2k views
Using OpenLayers (with OpenStreetMaps) and PostGis for rendering data acquired from GPS tracking device?
I'm researching and planing to acquire data from GPS device and store them in postGIS database, then use geodjango to process/work them out and finally chart them on a map with OpenLayers.
Will these ...
2
votes
3answers
2k views
Render vectors from OSM data in POSTGIS database
I'm a newbie when it comes to mapping application. I had successfully loaded my OpenstreetMap data in a Postgresql/PostGIS database. Now my problem is how to render the vector data (the POI's, ways, ...
5
votes
1answer
166 views
What is a “non-noded intersection”?
Can someone provide a precise definition of what a "non-noded intersection" is? There are various GIS platforms and toolkits that have errors with this text, and Google search results for this tend to ...
3
votes
3answers
337 views
How to Calculate length of polyline geometry for several tables in PostGIS?
PostGIS database contains several geometry (polyline) tables (with names "D1_r", "D2_r", "D3_r"). I calculate length for one "postgis layer" use request:
SELECT
...
3
votes
1answer
828 views
How do I perform a proximity search with Postgis?
OK, so I downloaded the Geonames database (cities1000) and wrote a small Ruby program to import them into my table (geo_cities). I then added geography column called geog.
So after all of that, I ...
1
vote
2answers
855 views
Adding shapefiles to PostGIS database
I was able to create a Postgresql database and then I executed,
createlang plpgsql geospecies
psql -d geospecies -f postgis.sql
psql -d geospecies -f spatial_ref_sys.sql
So now can I directly ...
6
votes
1answer
674 views
How to perform a spatial join of point and polygon layers in PostGIS?
I have a point dataset representing households that I want to associate with a parcel layer (i.e. assign its parcel_id). With ArcMap, I could spatially join the polygons to the points and specify that ...
5
votes
3answers
923 views
How to create spider diagrams (hub lines) in PostGIS?
I'm rather new to PostGIS but I have done a lot of reading. One thing that I have been searching for is a function that allows users to create a "spider diagram" (also called "desire lines" or "hub ...
4
votes
3answers
341 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 ...
4
votes
2answers
1k 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 ...
3
votes
3answers
110 views
How can I draw squares in PostGIS layers at different angles?
I am trying to draw two squares on a 45-degree angle and then merge them using PostGIS to edit. QGIS can draw squares but only on a perpendicular plane (eg, 0, 90, 180), and I need to be able to draw ...
3
votes
2answers
647 views
How do I use st_dwithin with meters?
I am trying to follow PostGIS ST_Buffer Radius Help to use a 50 meter distance but postgis is returning an error.
I am trying the following SQL,
SELECT id FROM table
WHERE ...
3
votes
0answers
266 views
How can I properly add PostGIS data into MapGuide Maestro?
I am having trouble connecting a PostGIS database to MapGuide Maestro. Actually, I have added the PostGIS data into Maestro, but when I click to validate the layer it shows an error message:
...
2
votes
1answer
521 views
Why does my PostGIS query fail with “current transaction is aborted”
I'm trying to create a vector layer in a QGIS project using a PostGIS query. QGIS is returning the following error:
Query failed
1 cursor states lost. SQL: CLOSE qgisf1
Result: 7 (ERROR: ...
2
votes
1answer
169 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 ...
2
votes
2answers
2k views
Postgis installation error
I am using fedora machine. I want to install postgis on my system. So this is what I have done
Installed Postgresql and supporting packages using YUM.
Created directory /sources to put all the ...
1
vote
1answer
421 views
GeoServer WPS Aggregation Functions Example
The scenario: I want to present a user with names of polygons from a layer in GeoServer. I then display the polygon(s) whose name(s) the user selected.
What I've done: I have a search box, which ...
0
votes
0answers
26 views
not able to view imported .tif file in geoserver
I am using geoserver. I have imported a .tif file using postgis, which has been saved in vector type layer in geoserver. Now, whenever, I preview it, the layer gets automatically downloaded as wms ...
35
votes
7answers
5k 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 ...
44
votes
7answers
1k views
How do I get started with PostGis
I have been reading a lot about it, but I am struggling to find a good beginner's guide.
Which tutorials/books do you recommend? My past experience involves python and arcgis. But I have never worked ...
16
votes
2answers
4k views
Best GIS system for high performance web application - PostGIS vs MongoDB
I am working on a web/mobile application based on location data. Since i am already familiar with MongoDB, i found the geospatial indexing of mongo is quite suitable for my needs. As i am mainly ...
17
votes
5answers
4k views
How to migrate GDB data into PostGIS without ESRI apps?
Can you tell me how I can load geodatabase data into PostGIS without having to install ESRI apps? The solution I found online talked about using ArcGIS to convert GDB to SHP and then importing SHP to ...
14
votes
2answers
2k views
How can I find a point inside a polygon in PostGIS?
How can I find a point that is guaranteed to be within a given polygon in PostGIS?
I am aware of the ST_Centroid function. However, the centroid is not always within a polygon, see below:
...
9
votes
1answer
4k views
Geocode quality: Nominatim vs. PostGIS Geocoder vs. Geocoder::US 2.0
I occasionally need to geocode >> 500,000 US street addresses (no features or intersections). I'd like to set up a geocoding service locally to handle these bulk geocodes.
I've used the Tiger-based ...
14
votes
6answers
2k views
How do I get started with GIS Servers on Amazon EC2?
Are there any tutorials, talks or presentations that discuss the use of EC2 or other cloud computing services to host GIS Servers? Has anyone had any experience in doing it with Amazon's EC2? How hard ...
14
votes
2answers
829 views
Moving a PostGIS Installation
I have a simple question:
I have a postGIS installation running on an old computer that I'd like to move. I spent a bunch of time playing with pg_dump and pg_dumpall without success. It seems the ...
13
votes
1answer
578 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 ...
12
votes
3answers
580 views
PgRouting - How to clip links when reaching max costs?
I have a polyline shapefile representing a road network and a second shapefile containing points. I would like to use PostGIS (presumably PgRouting) to identify sub-networks or service areas radiating ...
11
votes
1answer
410 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 ...
11
votes
4answers
4k views
How to get the nearest point on a linestring to a given point?
I've been using PostGIS in a long time now but never had to use the LINESTRING geometry ... yet! :)
Here's what I would like to do : I have a table of linestrings (representing streets of a given ...
13
votes
3answers
862 views
Visualization of 3D shapefiles with Mapserver and Postgis
I'm wondering is there a way to visualize 3d data with mapserver? 3D .shp files are in postgis database, and I already connected mapserver to database, but with simple layer in mapfile.
10
votes
2answers
204 views
How to identify and simplify point clusters with regard to time in PostGIS?
I just started to work with spatial databases and I want to write a SQL(PostGIS) query for automatic generalizing of raw GPS-tracks (with fixed tracking frequency). The first thing I am wokring on is ...
10
votes
6answers
1k views
Should I use a CMS for my web mapping application?
For my web mapping app, I am using GeoServer as server, PostGIS as spatial DB and OpenLayers on client side (as well as other JS libraries). The map is composed of base maps and vector layers. One of ...
8
votes
4answers
342 views
What is the best web editor and server for postgis?
I'm looking for a web editor (similar to openstreetmap) that works with an map Server (postGIS). This should permit edit and create new structures on map. What is the best option?
Can you help me?
...
14
votes
2answers
2k views
What are hardware requirements for a cloud hosted PostGIS & GeoServer?
I have been playing with a local installation of PostGIS & GeoServer. I would like to move my work online now to share it with several collaborators.
The proof of the concept map will consist of ...
9
votes
3answers
940 views
How to populate an undirected graph from PostGIS?
This question is more related to resources that I might not have identified yet, although I've been searching the web for a while.
In the project I'm working at the moment I need to run a ...
8
votes
4answers
924 views
Queries returning very big datasets in PostGIS
I have a PostGIS query that will return several million rows:
SELECT
t1.id AS id1,
t2.id AS id2,
ABS(t1.mean_h - t2.mean_h) AS h_diff,
ST_Distance(t1.the_geom, t2.the_geom) AS dist
FROM ...
7
votes
1answer
575 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 ...
6
votes
2answers
628 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 ...
27
votes
3answers
805 views
What coordinate system should be used to store geography data for celestial coordinates?
I am doing an astronomy project. I want to have the information about our images stored in a spatially enabled database. This, I would think, should be a very easy special case for GIS functions ...
10
votes
3answers
540 views
How to simplify a routable network?
I have a network graph that I need to simplify in the sense of reducing the number of edges. The idea would be to merge nodes that are located close together and remove the connecting short edges.
...
9
votes
1answer
1k views
How to change the SRID of exisisting data in PostGIS?
While importing my shapefile data to PostGIS, I did not select the proper Projection.
How do I now change the SRID of the data, without transforming the Coordinates?
8
votes
4answers
5k 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 ...
8
votes
1answer
1k views
PostGIS 3D in Action
I was wondering if there is a website that showcases Openlayers and PostGIS 3D in Action
