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

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382 views

Calculating Focal Statistics for Special Neighborhood?

I'm looking to calculate focal statistics for each cell of a raster, within a neighborhood of a specified criteria. Background - I have three binary rasters, each representing a single vegetation ...
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132 views

Point sampling along a pole-wrapping coastline with PostGIS

I am working on a task that requires me to get sample points every 1000 km along coastlines, and have run into a problem with Antarctica. From what I can tell, it seems to be an issue with the use of ...
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69 views

Best way to cut linestrings with points

i was checking the best way to cut linestrings by points. The scenario is: lots of streets, need the segments cut by intersect points, kind of this: I got linestrings (full uncuted by points) ...
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111 views

How to extract sublinestring from a linestring with overlapping segments

Problem statement: Given a bus route (defined as a linestring ln.the_geom), and a set of bus stop locations (pt1.the_geom,pt2.the_geom,...ptn.the_geom), divide the bus route into segments between bus ...
6
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88 views

Compute visibility graph on sphere

I have a PostGIS table with some polygons (stored using the geography data type). They represent regions on a spherical earth. For each pair of vertices chosen from among all the polygons, I want to ...
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279 views

Postgis - extrude a polygon

I want to extrude a polygon shape in postgis to create a pseudo 3D effect. To this end I have written a crude function to achieve it. This is very much test code and it creates a new Y vertice for ...
6
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565 views

Feature Service from plain PostgreSQL/PostGIS in ArcGIS Server 10.2

Using 10.2 ArcMap/ArcGIS Server on Windows I've successfully published some map services from my PostgreSQL/PostGIS data and now I want to enable editing the features through a JavaScript web app. ...
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169 views

Find and destroy duplicate OSM multipolygon/polygons in TileMill/PostGIS

In OpenStreetMap there are sometimes multipolygons where attributes are present on both the polygon and the multipolygon relation, such as the Grampians National Park: ...
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323 views

How to create a topologically correct dataset in PostGIS (with GRASS)?

I have shapefiles which I have loaded in postgis and now i am trying to use geometric function in postgis like ST_intersect and they fail because the data is not topological correct. I have tried to ...
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100 views

PostGIS Recursive Query Based on Line Connectivity

I'm having difficulty with a query. I have a network of linestrings, each with a value in the n_type column. This can be one of a handful of options. I'd like to generate a new table that groups any ...
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111 views

Spatial query too slow to handle bigger OSM extracts

I'm trying to compute some statistics for OSM data using PostgreSQL 9.3.5 and PostGIS 2.1.4. I started with a small bavaria extract which I downloaded from Geofabrik. The db schema is the normal API ...
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164 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, ...
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379 views

Geoserver WMS-T backend problems

I've been trying to set up a few timed WMS layers in GeoServer. They're simple enough, of the form ID(PRIMARY KEY) REGION DATE VALUE so for every region and date you have some value, e.g. the ...
4
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52 views

How to speed up simultaneous working with PostGIS layers in QGIS?

we are working on one big layer at the same time (10-20 people). Some of us use QGIS 2.8.1 and the other 2.6. The user with 2.8 have a lot of crashes (QGIS). The 2.6 users don't have this crashes but ...
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63 views

How to develop a QGIS plugin to fully run spatial queries with PostGIS?

I am developing a QGIS plugin that fully runs spatial queries with PostGIS. I developed all spatial queries which need some adjustment. I am looking for some resources or documents to know how to ...
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286 views

PostGIS: Merge any and all adjacent polygons

I would like to do adjacency tests on a parcel (polygons) layer and merge them if they fit certain criteria (could be size). Per the picture below, I would like to merge polygons 1,2,3 and 4, but not ...
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136 views

Vector to raster, then map algebra

I have a table of polygons representing travel time isochrones on particular days. For each origin point, there are five isochrone geometries (stored in separate rows). For each origin point, I want ...
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75 views

Diminishing performance of gdal_polygonize in a python subprocess for GRASS to PostgreSQL

I have written a python script to polygonize GRASS rasters into a PostgreSQL database using the gdal utility gdal_polygonize: sub.call('gdal_polygonize.py -8 gdb/quercus/{0}/cellhd/{1} -f ...
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120 views

Most efficient way to intersect overlapping polylines

I have 4 multipart polyline shapefiles (download a sample dataset here). The geometries are identical, except for the length of segments in each shapefile. They represent 4 variables describing an ...
4
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92 views

Postgis database query optimisation

I have a set of rasters in DTED format which I load into postgis database using raster2pgsql command line tool. Each of rasters is simply stored in a row and described by rid and a value of raster ...
4
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76 views

Create a Shape file from Sql dump file

I am trying to map data by querying a table called xyz. I need to show the the_geom data on the map. I have below query in my mapserver .map file: DATA "the_geom from xyz using unique id using ...
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155 views

PostGIS “Overlay” Style Union, not “Dissolve” Style

I'm trying to use PostGIS to do a 'union' of polygons. When I Googled "PostGIS Union", I found the ST_Union function, which performs what I would call a 'dissolve,' not a Union. What I actually want ...
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99 views

GeoServer ImageMosaic PostGIS index update

I use GeoServer where I created an ImageMosaic storage following this manual. When I create new datastore, all *.tif files are indexed into DB (PostgreSQL with PostGIS). How can I create new index in ...
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269 views

How to calculate the average distance among set of points as measure of closeness

I have three series (or tables) of points in PostGIS which I want to compare. I would like to know how "close" each series is when compared to the other two. In other words I would need some measure ...
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268 views

How to fix “Raster layer: Provider is not valid” error when loading PostGIS rasters?

I compiled and installed the current QGIS master as usual and I imported some raster data into my postgres 9.3 database with postgis 2.0.2 extension. Whenever I try to import the raster data into qgis ...
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145 views

How do I simplify the straight sections of (multi)Linestring in PostGres/PostGis leaving the curved sections untouched

I have (multi)linestrings containing upwards of 5000 points and I want to perform two simplifications possibly using Ramer Douglas Peucker or alternative methods in PostGis The (multi)linestrings ...
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649 views

How to use the linear referencing plugin?

I need a guide how to use this plugin properly, I'm a newbie on PostGIS and I'm trying to use the linear referencing plugin of QGIS. I've created a database on postgreSQL with the postGIS extension ...
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419 views

Hibernate Spatial - 'Invalid endian flag value encountered' Exception

I'm trying to run a simple query in Hibernate Spatial 4.0 on PostgreSQL 9.3. I have a number of objects in a table with latitude/longitude values, and I'm trying to query objects that fall within a ...
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109 views

Why are date vaules displaying a trailing 'Z' when layers are published with Geoserver and a PostGIS data store?

I have published various layers using Geoserver 2.2.x with a PostGIS 2.0.1 (PostgreSQL 9.1.x) data store. Fields that only have date values and not time/timestamp related values are stored as date. ...
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120 views

Add attribute table to a raster in postGIS

I would like to add attributes to a raster stored in a postgis database. I use the following command to insert the raster in the database: raster2pgsql -s 4236 -I -C -M ...
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437 views

Finding poi using st_dwithin in postgis

I am not familiar with gis or writing sql, so my understanding in this field is lacking. I have a hundreds of lat/lng geographic coordinates stored in a single table called Places like this: ID | ...
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393 views

Find points that fall within a radius using Hibernate Spatial

I am using hibernate spatial and postgis and i want to find the points that fall within a certain radius. Using this SQL: SELECT name FROM institution WHERE ...
4
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395 views

Extracting x,y,z values from a postgis linestring to python using ogr

I am trying to load a postgis linestring into python (using ST_DumpPoints) and extracting x,y,z coordinates, which is working but extremely slow..and if i mean slow, i really mean it (yes, it takes ...
4
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218 views

building larger polygons from smaller ones *without* a common id in PostGIS

I am looking for a means, using PostGIS, of reconstituting a set of polygons from tens of thousands of smaller polygon 'pieces'. This is a simplified example, with the pieces shaded: Unfortunately ...
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71 views

Visualizing variability in the size and shape of polygons

I am working with a data set of area restrictions imposed by criminal courts. These restrictions ban a person from entering a demarcated area. These restrictions vary in their size, shape, and ...
3
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257 views

Why are OGR (MySQL / PostGIS) connections extremely slow in QGIS 2.0 - 2.8 (when compared to QGIS 1.8)?

In our project we have been using QGIS 1.8 Lisboa with a MySQL database placed on a server accessed via local network since two years. Everything is working fine and quick. The vector layers can be ...
3
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422 views

How to import PostGIS layer with geography type to QGIS?

I tried to import in QGIS a layer from a PostgreSQL table with a geography type column created through the extension PostGIS. I noticed that QGIS doesn't seem to like the geography column... Here ...
3
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311 views

Creating Ellipse in WGS84, but with metric parameters

I have the function --Ellipse(x,y,rx,ry,rotation,#of segments in 1/4 of ellipse) SELECT ST_Translate( ST_Rotate( ST_Scale( ST_Buffer(ST_Point(0,0), 0.5, $6), $3, $4), $5), $1, $2) I have points in ...
3
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328 views

Is there a way to start the route on pgrouting from a coordinate that is not a node?

After execute all steps from this pgRouting tutorial, now I have a map that creates and displays routes, but as the routing methods rely on parameters representing vertex Ids that was created using ...
3
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148 views

Create a consistent topology using pgrouting

I'm developing an application that needs routing information for certain cities. First, I downloaded a openstreetmap datafile (*.osm) and then I imported it into a postgreSQL database using ...
3
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317 views

Shortest distance from pgrouting with cost not being length: optimal solution

I'm using pgrouting shortest_path_astar with a complicated cost function. It gives back the edges, vertices and costs. I would like to get the total distance of this shortest path (i.e., the sum of ...
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0answers
542 views

How to save table from PostgreSQL to MapInfo File?

I have two tables: 1 with geometry in WGS 2 with geometry in Local System I tried this: ogr2ogr -f "MapInfo File" output2.tab PG:"host=localhost user=postgres password=123456 dbname=postgis" -sql ...
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0answers
587 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: ...
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342 views

Can we do operations like Geo-referencing and Geo-coding in NoSQL Databses

I want to generate a map, using some spatial data provider like OSM. I am trying to put in some dynamic data-set on top of the base map. The data size is considerably large enough to be called as ...
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0answers
56 views

QGIS does not display all Features of Layer and behaves weird instead

I have a weird problem with QGIS trying to load a Layer from a Postgis Database When I open the Layer from Postsgis I have two choices: Method one: Either, I use the Panel "Browser", where I can ...
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0answers
32 views

How do I optimise performance on a local QGIS + PostGIS installation?

I'm learning how to manage a local PostGIS (ver 2.1) database, with spatial indexing enabled on the shapefiles that I've imported (using the PostGIS Shapefile Import/Export Manager). I have imported a ...
2
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0answers
53 views

Create Indexes Within a View? How could I Speed up Spatial Queries Over a View?

I´m trying to add a view from postgis using QGIS, what´s facile. The problem is that it´s taking too long to load it and to perform any kind of operation, for example, as simple as counting rows. It´s ...
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39 views

Calculate mean value of polygon from raster in PostGIS

I started with a NetCDF .gri and .grd raster file of the UK provided by a colleague. I clipped it in R to be only London, exported and converted to a ASC file, and then imported it to PostGIS using ...
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0answers
24 views

Are there methods of filtering gps-data with metadata?

In our project we captured GPS-tracks from a few electric vehicles in the timeframe of a year. In total we captured around 13000000 GPS-points this way. The captured data comes from electric powered ...
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17 views

Add individual fields to delete-log-trigger when deleting PostGis-Objects via QGis

I am using a PostGres Database with PostGis extension (on Windows). QGis serves as a client to access (visualize and edit) certain database-tables. I need to create a delete-log-table that saves all ...