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

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1answer
168 views

Calculate slope of line based off of point layer

I have a line feature class that needs to have its slope included as a field. I have a point layer that contains points and their elevations for the start and end of the line segments. How can I ...
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150 views

How can I convert Decimal to DMS for QGIS reprojection?

I have the following Lat/Long which I converted to DMS using the following calculator: Decimal DMS -96.2 96 12 0 -95.13 95 7 47.9994 29.3 29 18 0 29.98 29 58 55.1994 https://www....
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0answers
125 views

how to orthogonalize building outlines

I'm looking for a way to orthogonalize building outlines which I've extracted from a high-res DEM. I'm using the FOSS GIS stack (QGIS, GRASS, SAGA, PostgrSQL, PostGIS) and can code in Python (or Java)....
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1answer
80 views

pgrouting: function driving_distance does not exist

I tried to run driving distance function but got error. function driving_distance(unknown, integer, integer, boolean, boolean) does not exist LINE 1: SELECT * FROM driving_distance(' ...
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0answers
83 views

How do I make atlas with same pages but different layer sets?

I have a project in QGIS with multiple layers that I have to render separately. E.g. parks and distances to them (their buffers), travel time isochrons (interpolation with colors), density heatmap, ...
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1answer
113 views

Calculating Distance and Time on a network without the use of ArcGIS Network Analyst

I'm trying to calculate a distance and time for walking commuters (about 30,000 records) on a street network (NYC Lion). I have a starting and ending address for each record that have been geocoded. ...
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2answers
54 views

QGIS Processing Scripts Shared Code

I'm on a Windows 7 machine with QGIS 2.8 installed via OSGeo4W. I'm developing several processing scripts that make use of a few common pieces of code. Rather than maintain the code in each individual ...
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2answers
115 views

Critical facility pipe connections in python

I'm trying to find a way to determine pipeline connections located downstream a critical facility and score how far those connections are from the facility. Is there a way to accomplish the above ...
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2answers
106 views

How to measure the sum of the areas of each class in QGIS?

The project has a layer with several groups of polygons with different weights. Each group is associated to a weight. How can I get the sum of the area of each group?
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1answer
111 views

Finding the date of acquisition of Google maps in QGIS

How do i find the date of acquisition of the Google map on QGIS? Please help.
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2answers
764 views

Standard color mapping for NDVI?

I am currently generating some NDVI imagery using QGIS 2.8.2 and there are a multitude of possible color map scales that can be applied to the imagery. I was wondering if there was a preferred or ...
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1answer
74 views

Create primary and foreign key on Spatialite

I try to create a database on spatialite (for various reason, I can't use PostGis). I need to link a table to another one using a foreign key. The problem with spatialite is that it is not possible to ...
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77 views

SSL-Authentication failure

i try to include a wms-map into my current project. When i try to connect qgis 2.4. gives the failure-output: Attributes-request denied - failure in the SSL-protocol procedure. ArcMap 10.2 says: ...
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1answer
214 views

How to get the coordinates inside the polygon using python

I have a polygon and using this code snippet we can get the coordinates boundary of the polygon. canvas = qgis.utils.iface.mapCanvas() aLayer = canvas.currentLayer() coord = feat.geometry().asPoygon()...
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0answers
61 views

Nearest neighbour / spatial join with attribute condition

I have 2 point format datasets I wish to schematically join (manholes & gullies). I am content that I can join them by nearest proximity alone using e.g. NNJoin plugin. What I would like to do ...
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1answer
200 views

Does anyone know a way to do a supervised classification on a google maps image to show only hedgerows? [closed]

I would like to then use the hedgerows by bringing it into QGIS as a layer. I need to know what software to use and the method to make such a layer? I would like to use a google earth image in Grass ...
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3answers
206 views

Processing modeler: how to dissolve a vector layer and sum the attributes

I have a complex workflow prepared in the processing modeler, but I'm missing one step to link all the model. I need to dissolve a polyline vector in a single line vector that has as attribute the ...
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2answers
213 views

Suitable Raster processing methods to extract field boundaries from images

I'm trying to extract field boundaries and features from a lot of aerial images of agricultural land - and avoid digitizing these features manually. I've managed to get a crude raster file of the ...
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2answers
334 views

Running LAStools on QGIS 2.8: “missing dependency. lastools folder is not configured”

To be honest I'm not sure how to run LAStools from within QGIS 2.8. I'm trying to learn by experimentation. QGIS shows all the LAStools in the toolbox If I double click on a LAStool in the toolbox I ...
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1answer
149 views

Using GDAL library in QGIS plugin?

i've been working on my project to create QGIS plugin for raster analysis purpose. It will be easier if we use gdal library. Are we able to use gdal library to develop QGIS plugin? If so, how do ...
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0answers
33 views

How to pass a token value to QGIS processing modeler?

There are various places in the Processing modeler where I would like to pass the value of a variable. We're iterating through a bunch of features in an input layer. After the processing, we will have ...
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0answers
34 views

Couldn't load plugin sextantelwgeomprovider, QGIS 2.0.1 on Ubuntu 14.04.2

I'm getting this error message when I start QGIS Couldn't load plugin sextantelwgeomprovider due an error when calling its classFactory() method Traceback (most recent call last): File "/...
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1answer
275 views

What's difference between Topology and Check Validity in QGIS?

I would like to know what the difference is between the Topology Checker and Check Validity tools? Is there anyone who knows of a good document or tutorial that explains functions of these tools? ...
3
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1answer
72 views

Dependent Comboboxes in QGIS 2.8.2

I´m setting up an database for an archaeological project with PSQL. There I have a field "material" connected with a table "materials" containing things like metal, stone, etc. In a third table I have ...
2
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1answer
162 views

How can I create a polygon from points and assign it a color in QGIS using python?

I want to create a new vector layer, containing a polygon from a set of given points, and giving it a color.
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0answers
46 views

Is it possible to perform spatial join in PostGIS and keep all features?

I am attempting to create an employment change map using a hex grid. I have individual establishment data as points with attached employment figures. When I ran the spatial join using the postGIS ...
3
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1answer
51 views

QGIS Convert bathymetry shapefile from fillable to strokeable

In Java I would like to stroke the bathymetry depth lines instead of filling the area. I'm starting with the Natural Earth Bathymetric Data: http://www.naturalearthdata.com/downloads/10m-physical-...
2
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1answer
375 views

Grass 7 no longer works via the Processing Toolbox on Ubuntu

When I try to execute a Grass 7 algorithm via the Processing Toolbox in QGIS 2.10, 2.8.2 or 2.8.1, I get the following error: Missing dependency. This algorithm cannot be run :-( QGIS ...
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votes
3answers
148 views

How do I count the number of vector lines that pass though a given raster cell?

I am working on a project (currently in GRASS7 though I'm not against exporting to Arc or R or other software if necessary) where I am generating thousands of shortest cost paths (using the r.walk and ...
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0answers
495 views

Minidump Error Messages With Large Dataset

I'm using QGIS 2.8 on a system running Windows 8.1 (x64) with 12GB of RAM. I am attempting to run analyses of a very large database (.gdb format, 7.17GB). In attempting to run the "Join attributes by ...
2
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2answers
158 views

Pipeline connectivity

I'm trying to find a way to determine pipeline connections located downstream a critical facility and score how far those connections are from the facility. Any Thoughts?
2
votes
3answers
158 views

QGIS 2.2 is very slow while saving the edited layers

I am using QGIS 2.2 64 bit in windows 7 system. I have an issue while saving the layers after editing. Its taking more time to save my edits. Some times it's working fine but very often i am getting ...
2
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1answer
164 views

QGIS Composer: Force loading of all tiles on export

I face the problem that not all tiles are loaded on a map export via the QGIS composer. This happens randomly with all kinds of tile servers provided by the openlayers-plugin. Any hint how I can ...
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1answer
60 views

Shape Files and adding Label Data

Introduction: I'm still fairly new to GIS and have only had about 3 weeks experience. I set up an OSM server locally with .osm.pbf data and it worked just fine. When I pulled the map in the browser, ...
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2answers
506 views

Importing raster adf files with the additional files

I am trying to import a vegetation data raster in Esri GRID format from the USDA into QGIS. One file ("w0001.adf") can be added using "add raster", but the attribute table and other info register as ...
1
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1answer
125 views

QGIS models. deleting multiple columns is slow, is there a better way?

I have a process that has lots of items. This for some reason seems to make a difference to the time it takes to drop a column from a shape file during a model run. i need to drop MANY columns. QGIS ...
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0answers
88 views

cutting donuts in qgis

Im trying to cut donut polygons ready to go into a system that cant display them. Basically the exact opposite of this post: How to convert fake donut holes in polygons to real ones? I want to cut ...
2
votes
2answers
396 views

How to convert CSV file in VRT

I use the gdal executable in QGIS file, with a DOS command. I have a csv file like this (test.csv) : X Y -5.48 42.81 -4.78 42.52 -5.06 42.02 This coordinates are GCP. I would like ...
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1answer
154 views

Using GEOJSON offline in QGIS

I have some GEOJSON-Layers in my QGIS-project. The problem is, that when I zoom in or out, it takes very long to built up the window again. That's because it always loads it from the server. But I don'...
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1answer
246 views

Big performance difference reading shapefiles between QGIS and R

I'm trying to read the belgian landuse ESRI shapefile from geofabrik.de: http://download.geofabrik.de/europe/belgium.html In QGIS it's just a matter of seconds, but in R using the readOGR function ...
3
votes
1answer
86 views

Moving cursor using PyQGIS?

I would like to move the cursor to a given x,y coordinates of the MapCanvas. Is there an easy way to do this using PyQGIS?
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0answers
146 views

Generating shapefile of polylines using pyshp from a csv file and opening file in qgis

I tried the solution posted in: Creating Polyline from GML using PyShp?, Using PyShp to convert polygons in *.csv to *.shp files? and Using PyShp to create polygon shapefiles? to generate ...
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0answers
159 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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0answers
138 views

How to create multiple polyline transects with a certain orientation?

I am attempting to create multiple polyline transects and use them as cross-section profiles to analyze snow drifts on a landscape. Is there a method of creating multiple transects in such a way that ...
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0answers
26 views

Is it possible update a shapefile instead create a new one when using Processing?

Using Processing to add or calculate a field it's always necessary create a new shapefile? Is there a way to just update and keep using same layer?
4
votes
1answer
184 views

Grid vs. Polygon Overlay in R gives different results than in QGIS

I have a shapefile of range polygons. Each colored set of polygons represents a different group of species/genera/whatever. I next overlay a 5x5 grid onto this map. And then use join attributes by ...
2
votes
1answer
683 views

QGIS2WEB Plugin (openLayer3) for QGIS not exporting raster images

I am using the QGIS2WEB plugin for QGIS. I have added vector features as well as a raster image (.tif or .ecw) format. When I try to export the webmap, all the layers are visible expect the rasters. ...
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0answers
68 views

How can i add sub menu under custom top menu in QGIS using python

I have added "My Tools" Menu on top. Now i am clicking on "Plugin" then selecting QGIS Plugin bulider. Here in the menu field a drop down list is coming. How can i add "My tools" in this drop down ...
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0answers
183 views

qgis unable to connect to ms sql server using sql authentication

I am getting the following error when I try to set up a connection to a MS SQL Server database using sql server authentication. I did find a bug report from 2014, but that was apparently fixed and ...
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1answer
98 views

Capturing coordinates via snap with QGIS

I would like to know if there is a way to get and extract the coordinates of a node (one of the node that conforms a polygon) in order to use these pair of coordinates to georeference a DXF file, ...