Questions tagged [qgis]

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

6,578 questions with no upvoted or accepted answers
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Displaying images as part of multiattribute labels using QGIS

I would like to display images referenced in an attribute column as part of a multiattribute label, so that I can eventually print them with the map. I do not want to display geotagged images, since ...
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63 views

QGIS 3 3D Marker

In the 3D view I add 3d.obj files as Marker.works very well. Is it possible to add different 3D markers on different layers or categories. When I use 2 different layers with different obj files 3D ...
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447 views

Error using 'Clip raster by mask' in QGIS v3.8.2

I am attempting to clip a raster to a shapefile boundary (country boundary, 1 polygon) using the 'clip raster by mask' tool in QGIS v3.8.2. Both layers are in WGS84, so projection mismatch shouldn't ...
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1answer
201 views

MODIS Fire Product tile conversion to GeoTIFF problem

I downloaded a tile (selected tile in the picture) from https://ladsweb.modaps.eosdis.nasa.gov/search/order/3/MOD14--6/2019-08-09/DB/Tile:H25V6 I used gdalinfo on the file. It's output is Driver: ...
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51 views

QGIS export to PDF - rasterize only basemap layers but keep others as vectors

I am building my own map in QGIS 3.4 in which I created a basemap from ESRI satellite imagery and a ESRI hillshade overlay. On top I have several custom vector layers (country borders, city names etc.)...
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318 views

“Clip Raster by Mask Layer” produces zero values (and not Nodata) outside mask boundaries

This is my first question here. I have a big raster of the world's nighttime lights and want to clip it down to the Adm0 of a country: In order to do so, in QGIS 2.18 what I do is using the Clipper ...
4
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1answer
170 views

Symbol in layers panel not visible

I have a layer with symbology that includes geometry generators. It would appear that because of these the symbol is not visible in the layers panel. Is there a way to show the up most symbol (green ...
4
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1answer
77 views

Adding up several rasters to show the change

I want to add several images such that their change is shown in different colors. Such as the following in which I simply added two images in their grayscale. But I would like to have a colored ...
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288 views

EPSG:4326 being saved as CRS:84

I am trying to save a GeoJSON file in QGIS as EPSG:4326, but it keeps being saved as CRS84. EPSG:4326 and CRS84 are the same except CRS84 saves coordinates as long, lat - and EPSG:4326 saves them as ...
4
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1answer
192 views

3-D Terrain effects for vectors in QGIS?

I'm a bit new to QGIS, and making a few maps of roads through mountains. I'm looking to have a 3-D effect within my 2-D map. I got a DEM, made a hillshade, and blended a basemap over it. Nice ...
4
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1answer
171 views

Forcing color ramps to center around zero in QGIS

I have several columns of data that have percentage values. Some are positive and some are negative. In one particular column, the values range from -0.70 to +0.20. The mean value of the column is ...
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88 views

What kind of resampling will give the highest quality when building pyramids?

The resampling setting of the pyramids builder of QGis povides several ways to do so : nearest, average, gauss, cubic, average_mp, average_magphase and mode. I am not a specialist in the subject. I ...
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810 views

CadTools plugin functionality in QGIS 3 beyond Advanced Digitising Panel?

I've recently migrated to QGIS 3.6.0, and I've realised that the wonderful CadTools plugin is not compatible with QGIS 3. I tried to use the Advanced Digitising Panel, but it's cumbersome and not ...
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88 views

QGIS Server Adding a virtual layer

All my layers in the qgs-project-file are working fine as WMS-layers, but I only can't provide the virtual layer. The virtual layer is an ODBC-Connection of an Access-Database which contains one ...
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220 views

Change from LineString to MultiLineString when saving layer edits in QGIS

In QGIS, when a user creates a new single part line in an open editing session for a “Multi-Line” SpatiaLite dataset, the QGIS data type is initially a “LineString”. But, when the user commits the ...
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642 views

Convert TIFF raster layer to PNG

I have been given some images in TIFF format, and I need to convert them to the PNG format. I have been given that the TIFF file contains 4 bands: R, G, B, and NIR (which I do not need for the PNG). ...
4
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1answer
610 views

Rounding numbers in Raster Legend in QGIS?

Is it possible to have the numbers in the raster legend automatically rounded off? In the example below I'd like the labels to be 8, 29, 51 and so on. I know I can manually edit the labels, but is ...
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207 views

QGIS plugin external libraries in plugin’s directory

I’m developing my first QGIS plugin and I have to use two external libraries not included in the default OSGeoW64 installation: Couchdb and Pandas. I would like to include those libraries in my ...
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417 views

Question marks (“?”) in QGIS layer panel when using svg markers defined with “Data defined override”

When using svg marker symbols and set the path to svg file via Data defined override the svgs display well in the map canvas, but not in the layers panel (applies for QGIS 2.x and 3.x). svg marker ...
4
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1answer
471 views

Connect points to a line with shortest distance using QGIS?

On the picture below, I want to let my point connect to the line with the shortest distance and show the distance to me. I tried NNjoin, MMQGIS, v.distance But I still can't get the distance. How do ...
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1answer
115 views

Selecting or highlighting upstream elements

I would like to use the information from the Swedish SMHI related with their hydrological model elements (catchment areas) that have a Containment hierarchy structure, each element has the information ...
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217 views

Could not allocate required memory for image

I'm trying to export a 24k image (export set to 1650DPI) using the "export as image" function but I keep getting the "Could not allocate required memory for image" warning. I don't understand why ...
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387 views

How to use a WCS layer in QGIS for processing?

I have a GeoServer serving raster dem data out via WCS and can add the layer easily to QGIS (3.2) but when I try to use it as the input for an operation (e.g. HillShade) I get an error. Processing ...
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1k views

Add an API key to QGIS

I still can't seem to get this (Add an API key to QGIS for QOSM layer) to work. I need to add an API key to QGIS for OpenCycleMap. I'm trying to follow the path Web > OpenLayer plugin > OSM/...
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1answer
561 views

Backup QGIS (3.2.1) layer to independent PostGIS table?

I'd like to make multiple, progressive backup copies of QGIS (3.2.1) layers that are stored in PostGIS tables. I've tried multiple routes to export them as files on disk, but they all seem to destroy ...
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161 views

Adjusting georeferencing of GeoTIFF?

I have three thermal IR images of a boat acquired by a drone as it flew overhead. The images were taken at one second intervals, are GeoTIFF files and overlap one another. I don't know exactly how the ...
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548 views

Merging two overlapping rasters

There are two rasters A and B. A is smaller but within B and since A has more up-to-date pixel values, I was able to merge A and B with "Mosaic raster layers" tool in QGIS which replaces B pixel ...
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462 views

Investigating PostGIS table not showing in QGIS

I created a table in Postgres: create table eric_zs as select z.id, z.name, st_multi(st_union(a.geom)) as geom, count(*) from geo_as a inner join geo_zs z on a."ZS_id" = z.id group by z.id, z....
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142 views

Indexing Data in QGIS

Each time I open a my project, it starts to index and takes as long as up to 4 hours at times. My project has some layers that are stored in a remote database. How do I bypass the indexing process?
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95 views

Halftone effect gridded points inside polygon

I am trying to create smooth looking polygons by gridded points in QGIS (2.18.16), with a fading effect towards the boundary of the polygons (halftone effect). By using the 'fillGrid' function from ...
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206 views

Problem with encoding when clipping raster

I am using QGIS 2.18 on a Linux Mint computer using UTF8. I downloaded solar radiation raster data from PVGIS. The files are encoded as us-ascii (according to the linux command tool file -bi). Opening ...
4
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1answer
177 views

Use DEM elevation attributes in vector polygon?

I am modeling glacier retreat scatching polygons on DEM surface trying to come out with 3D scatch. Is it possible to adjust "height" of polygon to follow elevation of DEM surface (eg. glacier height ...
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318 views

QGIS Automatically Converts UTC Date-Time to Local?

I imported a WFS layer from a geoserver into QGIS and also into a web service that is based on Cesium. The geoserver fetches the data from Elastic search and serves it out as WFS. The date-time ...
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74 views

Creating Raster that sums up input polygons using QGIS?

I am using QGIS and I have a shapefile with buildings. From these buildings, I have built Buffer with variegating radius. The Buffer also have data about the demand for Parking spots for each building....
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259 views

Installing third party python library in QGIS 2.18.x Windows

We are running into a strange behaviour while trying to use pyoidc with QGIS 2.18.x windows standalone version. Due to pip/pipy no longer working with QGIS 2.18 (see this post), we installed the ...
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283 views

Using attributes for output filenames in QGIS Process Modeler?

How can I use process inputs (eg: Table field) inside an expression for an output file when using Process modeler? I have a process which outputs a raster, whose output filename should be the value ...
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596 views

Force layer reload in QGIS?

I'm working on integrating QGIS and PostGIS, but looking for a way to force a layer reload. I don't need it to be automated -- I'm happy to run a command every time I want to refresh the map. The ...
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234 views

Connectors do not appear automatically in easy custom labelling

I'm using the easy custom labelling plugin in QGIS 3. When I move a label away from its associated polygon a connector does not automatically appear as in QGIS 2.18. How do I get connectors to appear ...
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100 views

Bookmarking the rotation, scale, and extent in QGIS

I have one map that I want to bookmark at multiple rotations/orientations. However, when I use the bookmark tool to capture the view, I am only able to capture the scale and extent of each view, and ...
4
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1answer
187 views

Sharing properties for SQL server table in QGIS?

I have a project where most of the layers come from a SQL server. Most of the layers contain pointers to, and/or drop down list for, attributes so that there is consistency in data entry. This project ...
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788 views

Add color palette to grey-scale land cover GeoTIFF

I have a single band grey shade tiff image which does not have a a color palette associated with it. I need to open up the symbology and assign a color to each unique landcover class. I am looking ...
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0answers
158 views

Override/edit/fix WMS individual tile requests using QGIS

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 layer properties to "force" ...
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359 views

Drawing archaeological sections in QGIS

I'm trying to figure out a way to draw archeological sections in QGIS (example). We currently only draw the layers and features digitally (like this). When we make a section of features or a profile ...
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0answers
383 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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413 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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237 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 ...
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427 views

Is there a QGIS alternative for ArcGIS Schematics?

I want to draw a schematic drawing from a network.There is an extension in ArcMap that can do this. Is there an extension or a way to do this in QGIS or any other open source GIS?
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79 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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270 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....
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262 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 ...