QGIS is a cross-platform GIS application licensed under the GNU General Public License.

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1answer
31 views

print polygon from “the_geom” field in postGIS database

I have a postGIS database with plots and features (owner, area, address, etc) and I would like to print any selection of that like a card. I mean I would like to show each record in a page with the ...
1
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0answers
68 views

QGIS OpenLayers not working

I am an extreme neophyte with QGIS, so I maybe doing this all wrong. I have loaded the OpenLayers plugin as described in several online posts (and youtube video), and it is shown as listed in my ...
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0answers
12 views

Mosaic with LISS-III RESOURCESAT-1 images

I'm having problems with dark edges in normal or virtual catalog (.vrt) with LISIII LISS-III RESOURCESAT-1 mosaic. If I put no data value 0 in properties, change border by white (see figure) and I ...
3
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1answer
41 views

Looking for spatial analyst tool between raster and vector layers in QGIS

I'm aiming to do a similarity analysis between a raster layer and a vector layer. The raster layer is a 5-class ice map and the vector layer (points) contains ice jam events data. The goal here is to ...
2
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0answers
34 views

Finding and using mean and standard deviation value in field calculator

I am creating a field for a z-score of a particular attribute. This requires calculating the mean and the standard deviation for the attribute across all features. I've been using the statistics ...
1
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0answers
38 views

Viewshed Analysis for total beginner [closed]

I am totally new to doing this using QGIS. Can anyone help me to produce the following, which I believe is commonly known as a ZTV analysis. I am running Wein and have the Viewshed Analysis plugin ...
3
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1answer
44 views

Automating Interpolation in QGIS

I have a project in QGIS which involves interpolating several different variables on several different maps, then using the raster calculator to multiply some of the resulting interpolations together. ...
3
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1answer
31 views

How to replace a directory using QGIS Field calculator?

I have a column called Hotlink full of incorrect directories and I need to edit them. They currently read C:/ABCD/filename.pdf and I want them to read C:/Maps/ABCD/ABCD/filename.pdf The script I'm ...
7
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1answer
136 views

How to speed up QGIS project opening with large point datasets?

I recently loaded a big point set (in terms of memory usage) in the QGIS project i'm working on. This layer is necessary for the project but it is not used often. Most of the time is turned off. The ...
3
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0answers
24 views

r.sun from QGIS toolbox doesn't give realistic value about the hours of insolation

I have a problem with the GRASS module r.sun when I run it in QGIS. I would calculate the hours of insolation in a specific site during a specific day. When I ran the algorithm "r.sun" from GRASS, it ...
1
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1answer
21 views

Basic instructions for loading OS Terrain 50 data

Are there any basic instructions for using the OS Terrain data available online? I do not have an issue extracting - it is all sat in a folder ready to go. What I cannot work out how to do is to ...
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0answers
20 views

Spatial weight matrix QGIS - export to stata

I'm looking to estimate a spatial panel model in STATA, however, I'm running into difficulties creating a spatial weight matrix. For note my N=66 while my T=25. I'm a novice when it comes to ...
2
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0answers
18 views

Grid buffer in QGIS

I do have a raster file (grid) which I have processed before with the SAGA kriging tool. Is it possible to buffer this raster file a little bit (expanding the interpolated result) of 1 or 2 grids? I ...
3
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0answers
30 views

How to calculate average value of a raster, that is clipped by multiple polygons?

I am using QGIS 2.12.0. I have a raster of coherence value (SAR interferometry) and a land use shape. I wish to calculate mean coherence value for those areas with a specific land use. I split land ...
3
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3answers
43 views

Patching a large number of Landsat 8 scenes together

I need to extract land cover information (vegetation, water bodies, etc.) using Landsat 8 scenes. I have to extract the information on a country scale which means that I have about 15 scenes ...
1
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1answer
37 views

QGIS Zonal Stats Plugin - Python Console - compute one specific statistic

I think this is more of a syntax problem that I have here. But I am absolutely not able to figure it out. On a different Linux machine I got the following working: zoneStat = QgsZonalStatistics ...
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0answers
10 views

pinchZoom with qgis 2.82 and qt

I am working with qgis 2.8.2 c++ api and qt4.8.5 in my project i had to implement the pinchzoom because i use a 27" touch screen i am looking for information on how to use the qgis lib with the qt ...
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2answers
50 views

Copy geometry from one layer onto attributes of another?

I have two polygon layers, A and B, that have the same features but totally different attributes. I want to use the attributes from layer A, but I want them to have the more accurate geometry from ...
0
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1answer
54 views

QGIS - what is the core database system? [closed]

What is the core database system used by QGIS? When you launch an existing project that has multiple .shp files (with associated .dbf tables), is the core db system used to convert that data to its ...
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0answers
30 views

Why is GDAL/QGIS creating Geospatial PDF's with erroneous spatial data?

I have a GeoTiff that I wish to convert into a geospatial PDF for use in Avenza. I attempted to use gdal_translate, and also used the QGIS's Raster->Conversion->Translate which apparently just builds ...
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1answer
33 views

Choosing database for spatial and nominal data for current QGIS version? [closed]

For a nature conservationist community we are running a database (Access) in combination with ArcGIS with data about position, number and species. Our new goal is to convert the data into a (spatial) ...
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2answers
41 views

Importing OSM data into PostGIS and display into QGIS

I am new to all the GIS thing but I need to set up a full GIS infrastructure for a project. I have installed a Postgres server with PostGIS. That is on ancient hardware for now, 32bits processor with ...
4
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2answers
53 views

performance problem with PyQGIS: manipulating attributes

I have selected a vector layer with attributes slope and area. I want to combine all the features with slope 0 to 5, 5 to 10, ... , 85 to 90. The original features are to be discarded, and new ...
3
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1answer
67 views

QGIS Field Calculator functions

Using QGIS 2.12.3, within the Field Calculator "Geometry" section, there are certain functions, such as "area", that also have a corresponding term beginning with a dollar sign, i.e. "$area". I don't ...
3
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2answers
60 views

QGIS: Updating labels based on delimited text layer

I have a csv file that I am joining to a layer, then creating labels based on the joined layer. When creating the delimited text layer, I include the option to watch the layer. At the time of ...
4
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0answers
26 views

QGIS Atlas: Filter maps based on attributes (more than one)?

I have a series of maps with the same geographic boundaries but with different set of points (from the same layer). I would like to create an Atlas where the change is based on the attributes. A ...
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1answer
31 views

QGIS symbology: where are simple markers located in the system?

I would like to know, where are simple svg-markers (for example the one that is defined as "regular_star" in .qml file) are physically located in the system? I searched the system and looked inside ...
4
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0answers
36 views

Can I clip a geodatabase vector layer in QGIS?

I have a Vector layer loaded from a .gdb (geodatabase directory). I'm seeing my contour lines fine. I've drawn a polygon on top of the area I want to crop on a new layer. I select Geoprocessing ...
2
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0answers
38 views

WMS in QGIS on very high resolution monitors

I have a 2560*1440 px monitor which is bigger than what some WMSes can take. The layer doesn't load properly. Obviously this is due to QGIS requesting an image that is almost as big as the whole ...
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1answer
42 views

Addresses coming up in wrong spot

The map in which i am building will be used by an Emergency backup 911 system. I am plotting addresses from a csv file and geocoding with google. To do a test I did 100 addresses in a town I am very ...
2
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0answers
48 views

Why this pyqgis code cause crash dump in QGIS?

In ArcGIS there is gp.EucDirection to calculate Euclidean allocation, distance, and direction around a point, Is there equivalent function in pyqgis or gdal? I wrote a script with help of gene and ...
2
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1answer
38 views

Cannot edit postgis in qgis

I am currently trying to edit a layer in postgis by using qgis, but still out of luck. I don't know what I am doing wrong, and I guess it must be a very basic issue since I haven't found any question ...
2
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0answers
24 views

save shape file as grouped/layered vector file

I want to get the 10m natural earth countries file into a mercator projection and then into a vector file (svg, ai, etc) where for each country, its main land and any of its islands are in a single ...
0
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1answer
47 views

rotate point along line layer

I have two layers: point and line (postgis or shp) The line layer represent a hiking trail. The point layer the mountain passes. The points are exactly on the same position like the node of the line. ...
2
votes
1answer
21 views

QGIS Server sending UPDATE… WHERE NULL to postgis in a WFS layer

I am running a Windows Server 2012 server. PostgreSQL 9.3.5, 64-bit POSTGIS 2.1.3 QGIS Server 2.6.1-2 QGIS Desktop 2.8.3 and 2.12 I am using a Microsoft Surface Pro 4 tablet using QGIS Desktop ...
4
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0answers
40 views

Different styles in same label

I have a multiline label made of 3 attributes made through an expression like: "Length" || '/' || "Level" || '/' || '→ ' || "Bearing" || ' ←' I'd like to make the Length and Level lines in ...
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0answers
28 views

Shapes & categories

I am very new to this so please only smile if a dumb question. I have divided the oceans into 31 regions. Each region has various sub regions, example I have region 08; of which it is further broken ...
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1answer
53 views

projection (WGS84, UTM) issue

I have a question about projections. I have a hillshade raster with UTM 31N projection (I reprojected this from WGS 84). I also have a satellite image that I need to georeference. For georeferencing I ...
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0answers
28 views

How to create buffers having regard to topography with QGIS

I want to create buffers of 25 kilometers around points in a point-shapefile with q gis. So far so good. My problem is that I don't need an air-line distance of 25 km around the points, but a "real ...
2
votes
1answer
98 views

Huge file size after averaging two rasters

After I average two raster files (singleband gray, initial size ~700MB each) through QgsRasterCalculator() with formula "Raster1@1/2 + Raster2@1/2" the size of the resulting file is 2.9GB. Is there ...
2
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0answers
36 views

Setting extent with python in QGIS in new project

Situation: I am trying to write a simple python script for QGIS. The script aims to load one layer, zoom to given coordinates, and 'place a pin' there. The coordinates will change every time I run the ...
3
votes
1answer
84 views

Automating QGIS project composer printing?

I have a large project which consists of around 10x QGIS project files. Each project contains a print composer with an atlas set up to generate up to 10 maps. What is the easiest way to automate the ...
2
votes
1answer
51 views

How to display different layers with different CRS in one canvas in a standalone application?

I am a freshman of the pyqgis. Now I load the raster and vector data in the standalone application. The two data are same area, but in my canvas, they are at different places. I want to know how to ...
2
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2answers
47 views

Adding more than one legend in QGIS Print Composer?

I'm using QGIS 2.8.4 and I can't seem to figure out adding more than one legend to my Print Composer. Say I want a larger map and then an inset map -- showing perhaps a different classification/color ...
2
votes
1answer
57 views

Is it possible to do parallel processing in GDAL and QGIS?

It seems when processing with large raster dataset in QGIS, It causes crash dump, for example in QGIS failing to complete clip or intersect and crash dump in qgis , Is it possible to use gdal parallel ...
6
votes
1answer
74 views

Reason for error when saving shapefile in a new projection

I tried to save a WG84 shapefile as a UTM 16N projection and got the following error: "Export to vector file failed. Error: creation of layer failed (OGR error:Failed to open Shapefile `HF patients ...
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0answers
26 views

Getting started with Qt and QGIS

I would like to use GIS data as input in a C++ program, to do some work around data before to pass them to the program core, then display some maps. I would like to do that with the QGIS C++ API. I'm ...
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0answers
30 views

Problems opening ArcGIS 10.3.1 .shp files in QGIS

I'm using QGIS version 2.12.1-Lyon for Mac and trying to import a .shp file that was apparently created with ArcGIS 10.3.1. I keep receiving the "invalid data source" error message no matter how I try ...
3
votes
2answers
108 views

QGIS: How to analyze relationship between two layers of points?

I have a layer of points that are patients who were readmitted to the hospital and a layer of points of patients who were not readmitted to the hospital. I want to find geographical factors that ...
2
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1answer
28 views

QGIS: Distance units in CRS layer: WGS 84

First post so please bear with me. When I run a vector analysis on two shapefile layers with multiple points, I get a distance as my answer. What are the units on this distance?