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Questions tagged [qgis]

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

5,589 questions with no upvoted or accepted answers
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162 views

QGIS removes id field when saving as GeoJSON

I have a GeoJSON file of points which I am editing using QGIS 2.16.1. { "type": "FeatureCollection", "crs": { "type": "name", "properties": { "name": "urn:ogc:def:crs:OGC:1.3:CRS84" } }, "features": ...
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289 views

Making QGIS select correct feature id in PostGIS materialized view?

Can you tell me if there is a way to make QGIS automatically select the correct feature ID when I choose a materialized view in PostGIS? It's not a big deal, but it is nonetheless something I would ...
4
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72 views

Refining DEM with topographic survey?

I have a DEM that is based on LiDAR and I would like to refine a small area of the DEM with topographic survey points. Is there a good way to do this in QGIS?
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61 views

Is there a way to customize the Options dialog in QGIS 2.14.6?

I'm creating a deployment package to update QGIS from V2.8 (wien) to V2.14 (essen (LTR)). In QGIS 2.14 there is a new "Advanced" section under "Settings > Options", see screenshot: Can this menu ...
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250 views

Saving selected features by default in QGIS?

Is it possible in QGIS (2.14 or higher) to check by default "Save only selected features" when saving a layer and when features are selected ?
4
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44 views

How to restrict the creation of vectors (end vertices) to existing vertices in QGIS

My specific interest lies in network creation, however, knowing how to do that in general would be a plus. Is it possible to prevent a user from creating a line (line vector) without connecting it ...
4
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1k views

How to join segments of a line in QGIS?

I have lots of different lines composed of hundreds of segments in a Shapefile. I would like to join them spatially where every start (or end) point of a segment correspond exactly (or within a range ...
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608 views

QGIS snapping to the points of a line or polygon you are just creating

I have the snapping option enabled. I can snap to any point, intersection of created lines. But I can't snap to any vertex of the linestring I am just digitizing. Is there any option/plugin to ...
4
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98 views

Style rule based on feature adjacency?

Is there a way in QGIS to use an expression to define a polygon feature's color based on whether it's adjacent to other features? I would like to achieve something like the following: -If a feature ...
4
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231 views

How to handle large tables in QGIS using python?

I'm currently writing a plugin that calculates values based on a QgsVectorLayer's attributes. To display and print the values I'm using a QgsComposerTextTableV2. I have several problems with my ...
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1k views

Rotate feature by angle (QGIS)

Trying to offset a line by 10 degrees, rotating around an endpoint. I've read up on the older plugins and the new Rotate Feature tool, but am having trouble. I am using QGIS 2.8.9 Wien, reinstalled ...
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3k views

QGIS break polyline into line segments

In QGIS (2.14.3.) how do I break polyline features in their consisting (single)line features? I have tried the 'Explode lines' geoprocessing tool, but this destroys the whole polyline into very atomic ...
4
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278 views

Why is the unique ID field in Distance matrix empty for some inputs?

I have some coordinates in a .TSV file I import using the delimited text layer button. I have a different set of coordinates (actually, one point) that I import in the same way. What I've tried so ...
4
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59 views

Inputting Layers in QGIS for PyWPS Processes

I recently downloaded the PyWPS demo files from github here: https://github.com/PyWPS/pywps-4-demo. I'm having some trouble figuring out how to use some of the processes. In particular, processes like ...
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254 views

Tools to help migration from Mapserver to QGIS Server

I'm going to migrate a Mapserver WMS server to QGIS Server. I'd like to know if there are some tools or plugins that convert Mapserver mapfile (.map) to QGIS project file (.qgs). WMS responses (...
4
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1k views

Classify image using segmentation analysis using QGIS and OrfeoToolbox

I am working on a project where we have made a RGB orthomosaic using a drone which I want to classify using QGIS. I am not a fan of unsupervised classification, and I started exploring the ...
4
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93 views

Issues updating field values programmatically for particular field data type on 64bit Windows computer using QGIS 2.8.7

I have an issue with a plugin for QGIS 2.8 I'm developing when using it on a Windows 64bit machine (as opposed to 32bit). I am trying to update values in a particular field in my plugin, and the ...
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166 views

“Select a tool” error Saga: Accumulated cost (isotropic)

I'm trying to run Saga's accumulated cost operation in QGIS on a DEM and set of raster destination points, but keep receiving an "Error: select a tool" in the log after a failed run. There are no ...
4
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317 views

How do I limit the number of labels for similar objects in QGIS?

I'd like to reduce the clutter in this map by limiting the spacing or number of times that a particular label can appear. For example, the label 'US 15' should not appear within some set distance ...
4
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865 views

QGIS: Release file lock on file used in a processing algorithm at the end of script

I am using runalg (qgis:joinattributesbylocation) on two QgsVectorLayer objects. At the end of my script I'm trying to delete all the files created during the script. I can delete everything except ...
4
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105 views

Open QGIS project files in exclusive mode / alert if project file already in use

I have QGIS-Project-Files saved to a network drive and was wondering if it is possible to warn users that a project file is already opened by an other user to prevent concurrent editing of the same ...
4
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359 views

PyQGIS: vector layer does not get displayed after rendering

My project goal is to write a standalone app for Unbuntu and QGIS 2.14. It should get a layer of simple points and their name from a Postgres database and show them in a layer. In addition there ...
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1k views

“Geom-type or SRID not allowed” errors when importing sqlite layer to DB manager in QGIS?

I am trying to import an sqlite file to the QGIS DB Manager with default import settings. While the layer displays fine in the graphical interface, the DB Manager only partially loads it, stopping ...
4
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404 views

Aligning two raster layers in QGIS?

I am teaching myself GIS in baby steps, I recently acquired aerial imagery (employing RGB and NIR-GB sensors) using a small UAV with the intent of generating a map in a small plot of land. After ...
4
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99 views

Is it possible to have a locked TOC in QGIS

I would like to customize QGIS for a custom use case where the user will work with a very simple customized UI and will just digitize features in existing layers. Therefore the TOC should be locked, ...
4
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266 views

Thematic map exported using QGIS2Web is extremely laggy

I have made a world thematic map and added layers of data for creating graduated color scheme on the country level. I need a interactive map as an output which shows values when user hover over any ...
4
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0answers
719 views

module object has no attribute classFactory

I asked this question several days ago on the QGIS developer list but didn't get any love. I'm hoping someone can help me resolve this error. I have a custom repo and a custom plugin that I'm ...
4
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501 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 Tools ...
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223 views

Stretch to MinMax results in blank render output in QGIS?

I am a new QGIS user, and I can't figure out if I encountered a bug. If I have a multi-layer image, and "Multiband color" -> "Stretch to MinMax" selected I get the following behaviour. QGIS takes a ...
4
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78 views

Center my contour values in QGIS

In QGIS have an issue with my contour value labels being pushed to the edge of my map, instead of lining up at the center where they seem to have more space. Does anyone know why this happens for some ...
4
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336 views

Adding intermediate contour values automatically in QGIS?

We have 100's of elevation contour shapefiles. In each file, only the 10th contour line has values (200, 450, 700, etc..). We have to attribute values for all the intermediate contour lines (2nd line ...
4
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187 views

Can you build a login window in QGIS?

Can you build a login window before loading QGIS interface? I use QGIS 2.8 I just built message windows when loading QGIS interface, but no more.
4
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512 views

How to specify TIME parameter in URL for WMS-T server in QGIS?

Does anyone know how to specify the time parameter for accessing data through a WMS-T server in QGIS? I am trying to access fire data from FIRMS web server :(https://firms.modaps.eosdis.nasa.gov/web-...
4
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252 views

SAGA Tool in QGIS Error: Load table: Proj.4-WKT Dictionary… failed

I have some problems with running SAGA tools in QGIS. I've downloaded and installed the software via the OSGeo4W Installer. It downloaded QGIS 2.12 and Saga 2.1.2. I wanted to use the Tool "Shapes To ...
4
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238 views

How are costs returned by the pyQGIS implementation of Dijkstra calculated?

How are the costs returned by pyQGIS implementation of Dijkstra (QgsGraphAnalyzer.dijkstra) calculated? As far as I know, these costs correspond to the distance from the starting node to each of the ...
4
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0answers
4k views

How to import netcdf in qgis

I have been trying to impot netcdf files following this guide online http://www.ggiuliani.ch/download/netcdf_qgis_GG.pdf into qgis 2.10 with no success. ALthough the file is imported, the dimensions ...
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1k views

QGIS Server WFS/WMS user and pass authentication

I configured a QGIS project as follows: As you can see, QGIS Server is now serving two layers using WFS or WMS service. These two layers don't have the user/pass parameters saved in their layer ...
4
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655 views

Seeking QGIS plugin with functions like ArcScan?

Is there a QGIS plugin which does raster scanning, like ArcScan. Typical QGIS Vectorization returns very bad outputs that have thousands of 'islands'. I require a clean and efficient vectorization ...
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175 views

How can I see the 'Custom Options' metadata following Save As in QGIS?

In QGIS 2.10 Pisa, I've right-clicked a layer in the TOC and used Saved As ... to save a shapefile with a new name. During this process, I used the Custom Options (Data Source and Layer) to include ...
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0answers
295 views

Is it possible to lock the layers using Qgis API Python?

I would need to load and "lock" two layers on the map. Locked means that layers cannot be removed from the layer registry. When I say removed I mean removed by the user using the QGIS interface (the ...
4
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0answers
120 views

Importing ArcGIS Vector Layer “drawingInfo” to apply to QGIS layer style?

It is possible to import vector layers in GeoJSON format either directly from an ArcGIS MapServer URI, or from a local JSON file sourced from such. ArcGIS JSON has a "drawingInfo" key (example below). ...
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333 views

Merge line segments by length (in QGIS)

I have a layer containing line segments which are connected by their endpoints (e.g. as within a street network). I'd like to merge (union) polylines within this layer into one feature until following ...
4
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0answers
379 views

QGIS 2.10.1 & SQL Server 2014

I'm struggling to load spatial data into QGIS from SQL Server 2014. I have a table with 4 geography columns (3 are polygon layers, one is a point layer). The table has a primary key column that is a ...
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0answers
1k views

Can I use GeoJSON GeometryCollection in QGIS?

I want to create a GeoJSON that contains multiple geometries to be used in QGis later on. Now I red through the specs here: http://geojson.org/geojson-spec.html#geometrycollection When I simply copy ...
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0answers
561 views

Cutting donuts in QGIS

I'm trying to cut donut polygons ready to go into a system that can't display them. Basically the exact opposite of this post: How to convert fake donut holes in polygons to real ones? I want to cut ...
4
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0answers
368 views

MMQGis plugin error

I am using QGIS 2.8.2 and I'm trying to geocode some addresses, but when I run it, I get this error: An error has occurred while executing Python code: Traceback (most recent call last): File "C:/...
4
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0answers
162 views

Drawing “proportional” buffer using QGIS or GRASS?

I'm working on aquatic vegetation and have a shapefile representing floating vegetation in a lake. By some studies, we know that submerged vegetation extends for a certain extension based on floating ...
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0answers
220 views

SAGA hydrological analysis in QGIS 2.8 on Mac

I am running QGIS 2.8 on a Mac machine and I want to calculate the catchment area using SAGA - Catchment Area. It starts running but after a while when QGIS wants to open the generated files there is ...
4
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0answers
950 views

How to clip a big shapefile from another shapefile's extent

I am working on mangroves in Sundarbans (Bangladesh / India), using Landsat pictures. I need to equalize them in reflectance, before classification, for the evolution of the biomass in this region. I ...
4
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0answers
545 views

Setting up PyCharm CE 4 to work with PyQGIS library in Mac OS

I am trying to set up pycharm to work with pyQgis library but with not success till now. I am using PyCharm CE v4 and QGIS version 2.8 I have tried to implemnte the instructions of several posts like ...