Questions tagged [qgis]

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

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Speed up identify in QGIS

I have just transferred my Postgis database onto an RDS server, and there is a bit of a performance hit when using the Identify tool in QGIS (3) compared to localhost. I presume this is mostly network ...
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115 views

How to override/edit/fix WMS individual tile requests using QGIS

My question is as follows: I've added a WMS layer into QGIS but when it then goes to display the map and display the tiles, the request is different to what it should be. Is it possible within the ...
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187 views

Voronoi Polygon Algorithm seems to exclude a Point from processing

I am using the QGIS (2.8.1) Voronoi Polygons Algorithm on a point shapefile. See image below, the red triangles are the points I am using. The resulting polygons miss a part (around HP87). Any ...
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299 views

Avoid duplicate labels on river sections and choose placements

I am trying to label rivers's names. The rivers include multiple sections. I have many repeats like "fleuve Loire ". How to avoid labeling repetition? "Merge connected lines to avoid duplicate ...
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327 views

QGIS Zonal Statistics for polygons is missing results?

I am carrying out an analysis using QGIS 2.14.1 where I am dealing with point data that have been randomly displaced by either up to 2 Km or 5 Km. I have generated a buffer of the appropriate radius ...
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186 views

Creating labels with table style

Hello I'm trying to create a label in QGIS that is formatted similar to the "table" styled yellow labels in the photo below. The attached image was from a map created in AutoCAD. I would like the ...
4
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208 views

Using transform function in QGIS layer geometry generator?

I'm trying to use the following expression in the geometry generator in a QGIS layer to show a 1-mi boundary around points: buffer(transform($geometry, 'EPSG:4326', 'EPSG:2877'), 5280) However, the ...
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71 views

Do the elements in Print Composer have any identifiers in QGIS 2.18.14?

In QGIS 2:18:14, it is possible to refer to elements in the Print Composer? How do I name and identify an element in another element? E.g., on a label, call the contents of another label and use its ...
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201 views

How to set different random colors to adjacent lines in QGIS

I have several line layers which i am trying to style with random colors. I want the lines styled in such a way that adjacent lines are assigned different colors so that each is clearly differentiated....
4
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224 views

Is it possible to get the compression level of a GeoTiff?

When creating a GeoTiff and using Deflate or LZW as compression it is possible to select the level of compression from 1 to 9. Is it possible afterwards to see which level was used? I have a lot of ...
4
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570 views

Emerging hotspot analysis (space-time patterns) in QGIS

I worked with crime data a while ago and was really impressed by the possibility in ArcGIS to detect significant hotspots and their development over time (Emerging hotspot analysis). Does anybody ...
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206 views

Orientating Contour Labels Uphill in QGIS?

I'm quite new to QGIS and I'm trying to style topographic contours. I have managed to style the lines the way I'd like but I'm having trouble with the line labels - I can't style them so the labels ...
4
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0answers
242 views

Mapcache zooming problem

I am using mapcache for caching map raster data. Everything works fine except the map zooming, because at the some zoom level i am getting pink tiling images. This is my mapcache xml file: <?xml ...
4
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155 views

QGIS 2.18.14 vector Clip analysis producing erroneous result

I am trying to perform a vector clip analysis (vector-->geoprocessing tools pull-down menu) using two complicated vector layers and am getting erroneous results. The clip 'Input layer' is shown here: ...
4
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103 views

Automatically creating user CRS from postgis in QGIS

I have my custom CRS in table "spatial_ref_sys" in database. When I load layer from schema "public", QGIS create this CRS. But if layer from other schema, it's not. What I need to solve this problem?
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336 views

Improve washed out blurry composite Landsat 8 image in QGIS

I want to create a composite image using Landsat 8 bands. I followed the steps to do so (creation of virtual layer, high resolution, separate) and adjusted the bands' colors (red 4; green 3; blue 2) ...
4
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1answer
223 views

PostGIS table shows twice in QGIS Browser panel

I've observed for a while that for many (but not all) of my tables, QGIS 3 (2.99) shows the same table name twice in the Browser Panel on the left, when I expand my PostGIS data source. The first ...
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875 views

QGIS plugins not installing

I'm trying to install plugins on a fresh install of QGIS 2.18.12. I can connect to the plugins repository but trying to install any plugin fails with the error message: Failed to unzip plugin package....
4
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117 views

Relation/difference between area calculated by PyQGIS QgsDistanceArea().measurePolygon() and QGIS $area

What is relation/difference between area calculated by QgsDistanceArea().measurePolygon() of PyQGIS and $area from geometry $area in QGIS? I am getting area as 0 for one polygon using QgsDistanceArea(...
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121 views

Updating PostGIS layer from another vector layer in QGIS?

I have a vector layer that contains way points that I load using "load vector layer" from a gpx file. I am attempting to add these new points to an existing postgis layer by simply copying and ...
4
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437 views

Using csvt file to define column field types - Vector vs Delimited text layers?

I've discovered for myself and also read other post about an issue using csvt file to define the field types - String, Integer, Date, Real ect... The csvt file appears to work as described when ...
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105 views

Preserving Vector Attribute Types When Processing Vectors

Qgis seems to change vector attribute types for certain processes. Is there a way to force preservation of the attribute types? My situation: I have five vector layers I want to merge, all shapefiles,...
4
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0answers
110 views

QGIS integer raster stats calculation error

I am comparing two raster temperature files generated from two different sources that use different algorithms. One of them is provided as a floating point (temp(C)) and the other is integer (temp(C)*...
4
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0answers
512 views

Computing the slope of a road using DEM

I work with QGIS 2.14 and I want to create a map of road network showing the slope of each road with at least this scale: <3%; 3-5%; 5-7%; 7-9%; >9%. I already have a vector layer of roads and the ...
4
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90 views

Sphere rendering inside out using QGIS on Ubuntu?

I'm trying to use QGIS to show earthquakes around a 3d globe. I changed my CRS to 'Sphere_Van_der_Grinten_I' and it rendered like this: Here's a report from Hardinfo on my system and display: ...
4
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112 views

How much raster data can TimeManager handle?

I have average wind speed data for the UK at 5x5km grids in raster form for every month over 10 years. I load the first 7 months into timemanager and the animation is fluid without any loading/down ...
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557 views

Import Pandas or any Python module into QGIS internal Python

(Also asked in stack overflow - https://stackoverflow.com/questions/43244062/import-pandas-or-any-python-module-into-qgis-internal-python ) I am developing a plugin for the current LTR version of ...
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552 views

Clip of polygons does not work properly by invalid geometry

I want to clip a polygon shapefile by another polygon shapefile. Input polygon is the green one (first), clip polygon is the light blue one (second) and the result should look like the dark blue one (...
4
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0answers
136 views

Layers from GRASS db won't load in QGIS 2.18.4 desktop

I have been learning QGIS online but now I am stuck at a module. I am supposed to launch a project that includes GRASS vector and point layers. However, when I do so I always receive the 'Handle bad ...
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286 views

QGIS Simple fill symbology for vector layer not exporting to pdf

I'm trying to use simple fill i.e. Diagonal X, on vector layers, the layers look fine on the composer when zoomed out (for example to a scale of 1:6,000) however when I export to pdf the distance ...
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997 views

QGIS: CRS, ellipsoids and area calculation

I have a doubt about dynamic CRS, ellipsoids and area calculations. I am using QGIS 2.14.0 (still waiting for IT to install 2.14.11...) When I load a polygon table into a new, empty project, it comes ...
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97 views

Avoid adding “_1” to field names when reading csv in QGIS?

When I read my csv file below "Data Source","World Development Indicators", "Last Updated Date","2017-02-01", "Country Name","Country Code","Indicator Name","Indicator Code","1960","1961","1962","...
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601 views

Right-hand-rule in QGIS

It seems that there isn't a plugin to perform the right-hand-rule on a layer or selected features. Can this be done by using some Python code? Is there a function that works in the same way as ...
4
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1answer
171 views

QGIS how to handle circular but non-closed lines

I use QGIS 2.18.3 and I have a shapefile with around 30,000 lines and a lot of invalid geometries. It is imported from a CAD project. I managed to solve most of the invalidities with the break ...
4
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0answers
131 views

How to change the color ramp of a rule based styling in QGIS?

I use rule-based styling in QGIS, in order to do spatial quantile, computed in R. If I want to change the color ramp, I need to either: change every class color, or set graduated then change the color ...
4
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669 views

QGIS 2.18 + Mac OSX sierra crashes and slow

I've been using QGis for quite a few years on Mac OSX, never had a problem. Now with the current configuration of OSX Sierra + QGIS 2.18.1 many project files that ones were opening nice and smooth ...
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333 views

What's the fastest way to convert large csvs to point shapefile

I'm working in QGIS, and my current method to change csvs to shapefiles is to import them to QGIS, right click and save as shapefile. For large CSVs (over 100 million rows) it can take quite some time ...
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333 views

How to select points with point ids from external list

I have a point shp and list of point IDs in CSV file which match with point IDs in the shape. Points in SHP have location while points in the external file don´t. How can I select points in the shp ...
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225 views

Activating GRASS utilities in QGIS Processing toolbox via text descriptors

This is a new follow-on question from this one. Following the documentation outlined in the answer, it is fairly easy to set up a descriptor text file for standard utilities that exist but aren't in ...
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215 views

How to add a Google map layer in a pyqgis script

I'm creating a python plugin for different users that has the layers that each person need to use and work with in QGIS. I have no trouble adding rasters from Geoserver using the following code: ...
4
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0answers
306 views

Is it possible to link symbol fill colors between different geometry types in QGIS

I would like to link symbol colors between two layers of different geometry types (point and polygon). I have tried to save/load style and to copy/paste but I don't think its designed to work that way ...
4
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0answers
270 views

Reopening QGIS project from PyQGIS

I am opening a QGIS project using the following snippet: new_project = False if not os.path.exists(self.qgis_project_path): prj_template_path = os.path.join(self.qgis_template_path, 'project.qgs')...
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619 views

QGIS connect to WCS using OAuth2

I'm trying to connect my QGIS to a WCS service using OAuth2 authentication (see curl example below to understand the authentication workflow). the problem The option "add WCS layer" seemed to be the ...
4
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0answers
188 views

How to generate a map showing more than one feature from the coverage layer of Atlas Generator in QGIS?

I have a shapefile (point) with occurrence records of species. There are at least two features for each species, one for currently record and a second for past record. I need to produce one map for ...
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0answers
156 views

QGIS attribute table displaying wrong features?

In QGIS 2.18.1 I set up Attribute table to 'Show features Visible On Map' but in the form view in the list are definitely more features than visible in the map. In the screenshot below two features ...
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401 views

PDF looks different from print composer

When I create a map in print composer the map looks exactly how I want it, but when I save it as a PDF some of the sympbols have changed. Note the roads are still visible in the PDF but some have ...
4
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0answers
58 views

QGIS Updating three layers at a time by editing the edge where all the three layers concur

I have a map with three main layers: Roads (Polygons) Sidewalks (Polygons) Curbs (Multilinestrings) I need to adjust the edge where all the three layers concur to the cartography layer (the gray ...
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0answers
664 views

Open .mdb files in QGIS 2.14.1

I Use QGIS ver 2.14.1 I've got a little problem here I already following how to open mdb at link below : QGIS 2.4 access .mdb add error But error dialog box always pop out when I click "OK" (after ...
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4k views

Is there an “undo” button in QGIS 2.18?

In ArcGIS there an option of "undo" button I seek this option in order to return my steps if it necessary. I try to find such option in the menu and didn't found any like it. What can I do?
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0answers
327 views

Using Proximity tool in QGIS 2.16

I am using the proximity algorithm to generate a raster proximity map indicating the distance from the coast (points shapefile) of my study area and the center of each planning units (I have divided ...