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Questions tagged [qgis]

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

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QGIS: RGB image file to Y'CbCr and other Luma+Chroma Representations

is it possible using QGIS on windows to convert an RGB image file to Y'CbCr and other Luma+Chroma Representations format. I've seen various formulas for this written in MATLAB and R. I am looking to ...
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0answers
20 views

Grid rendering in QGIS

Rendering a grid in QGIS causes problems: The outmost grid line is not drawn on different zoom-levels: Here it is ok: While here it is not ok: I have tried to change these rendering-settings, but ...
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1answer
15 views

Customizing QGIS plugins

Is a user legally allowed to make changes to available plugins according to his needs? e.g. changing UI, code etc but not the licenses and other info.
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1answer
10 views

QGIS Performing Table Joins returns NULL

I followed every step of this tutorial but when I join the distToRoads and distance in m I get a table distToRoads which contains just the null vaues, why is that? Tutorial: https://www....
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1answer
23 views

Continuous buffer from individual polygons in QGIS

I have a stream segment for which I am trying to find a buffer around with criteria as 5m of elevation. So for each straight line within a stream segment, I have found buffer (polygon) for it. Now I ...
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1answer
30 views

Export road system to CSV file

I'm using QGIS to extract coordinates of a road network. Concretely, I downloaded a mbtiles file from Internet and loaded the file into QGIS like following: Then I tried to export the layer ...
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2answers
19 views

How to get just land and water layers in QGIS with QuickOSM?

How can I just get land and water layers that I can style with different fills and outlines? Really - Just "land is green, water is blue" layers (that I can then add other layers on top of) I'm ...
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1answer
20 views

Expression returning wrong value in QGIS Field Calculator?

My QGIS Field Calculator expression: case when "field_value" = '' or "field_value" <> NULL then (if( "field_value" = '', 'N', 'Y')) end returns null value even if "field_value" has something ...
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1answer
33 views

Updating one or more fields in QGIS?

I have 5 layers: NAM_USA (It has four fields of our interest, named 'bare', 'sand', 'woody' and 'built' depicting feature counts in each of the below corresponding layers.) Baresoil Woodyland ...
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1answer
59 views

Exposing GRASS GIS add-on in QGIS Processing framework?

Having QGIS and GRASS GIS 7 installed, how can I expose a GRASS GIS add-on, which has been installed using g.extension, in QGIS' Processing framework?
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1answer
24 views

QGIS Join by location (summary) returns null

I am trying to count points within polygons (311 calls by Census tract). Both shapefiles are EPSG 4326, and I've done define projection just to double-check. Every time I run Join attributes by ...
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0answers
13 views

Spatial join for closest features and using a sum merge rule in QGIS

I am trying to perform a spatial join based on nearest neighbor ("CLOSEST") spatial relationship in QGIS, and by summing the results of the join where multiple matches occur. In ArcMap there is a way ...
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0answers
22 views

Measures of printed map in QGIS

I created a simple map with a point and a buffer (3 km) in QGIS2.18 (and also 3.4) with CRS WGS84 UTM33. With QGIS Composer I created the layout adding the scalebars (for 500 m and 3 km) and printed ...
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2answers
82 views

QGIS virtual layer functionality does not seem to support memory layers

I have a memory layer loaded in the QGIS virtual layer in the data source manager. I am trying to run a very simple query: select * from layer Here is a snapshot: While this works for the physical ...
3
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1answer
26 views

Fixing self-connect polygon in QGIS 3.2

I'm trying to clip a soil map layer and am getting invalid geometry that affects my clip result. The problem appears to be a self-intersecting polygon. I've tried using the 'check geometries', and ...
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1answer
27 views

How can I select feature, except null values?

I want to select feature except NULL values. In the past, when I using ArcGIS, I used 'select by attributes', and type like 'NOT "field name"=NULL' But now, in QGIS, it doesn't work. Just like ...
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0answers
13 views

Using alternate glyphs/stylistic set with label font in QGIS?

I am using a non-standard font for my labeling in QGIS (the font is jost*, modeled on Futura), and would like to use one of the alternate stylistic sets. It's easy to do this in Word. Is there a way ...
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1answer
29 views

How to convert multiple shapefiles of different geometries into a georeferenced raster

I have multiple shapefiles extracted from OSM vector data, as shown in the image bellow: I want to save them into a raster file with a black background. Is there a way to do that using QGIS or ...
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1answer
21 views

Clipping Vector by Custom Raster Extent in QGIS?

I have a raster image (elevation map from DEM) where I have limited the rendered elevation to only 3,500' and higher. I would like to convert the boundary/extent of this rendered image into a vector ...
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0answers
14 views

QGIS install on OSX with homebrew: “You have other linked versions!”

I have an OSX Mojave setup where I've already installed PostGIS and GDAL using Homebrew. Now I'd like to install QGIS. I'm trying: brew install qgis But... I'm getting lots of warnings of the form: ...
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0answers
14 views

Installing QGIS on OSX: “QGIS requires Python 3.6” but 3.6 is already default Python

I'm trying to install QGIS on OSX Mojave from the official installer. I have system Python 3.6 installed, as the default: $ which python $ ls -al /usr/local/bin/python lrwxr-xr-x 1 me admin 44 18 ...
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0answers
14 views

Kernel Density Estimation Weighting Factor

I dont understand where is this weighting factor coming from, does it need to be in the quakeLyr in the attribute table named with "mag" or? ##Now, we can run the kernel density estimation algorithm ...
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0answers
21 views

SDO Oracle Table not recognized as Geometry in QGIS

I can connect to the Oracle Database with QGIS but spatial table/layers are not recognized as such. I have read the following in the QGIS documentation: Normally, an Oracle Spatial layer is ...
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0answers
24 views

Changing the field colour/design on a QGIS 3 QT attribute form?

I have problems with changing the physical appearance of a custom attribute form (QGIS 3, Windows 7). A custom attribute form can be designed, for use in QGIS, using QT / QT Designer. In QT Designer ...
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1answer
34 views

Cheapest path through polygons and lines from point to point

I want to find the cheapest path or the least cost path from one point to another point. The points are part of a vector map and do not lie on a network. All features being part of the map have ...
2
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1answer
28 views

Central deployment of startup.py in QGIS

In QGIS 3 on Win10 we use a startup.py script for setting up e.g. database connections and a couple of other things, residing in C:\Users\me\AppData\Roaming\QGIS\QGIS3 What we are after is to ...
2
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1answer
39 views

Get OGR driver Name for QGIS VectorLayer

Is it possible in the Python script to get the name of the OGR driver (for example, "Esri Shapefile" or "MapInfo File") for the QGIS vector layer? __ QGIS 2.18
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2answers
141 views

Apply Line Pattern Fill to LineStrings?

I am trying to print out a network map using black/white hatching patterns, similar to Black/white hatching pattern fills in QGis but for Lines. Is there some trick I can use?
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0answers
11 views

XML to TIFF raster and zonal statistics in QGIS

I was sent several XML files of a flood model's peak extent that works fine in ArcGIS, I need to use zonal statistics, and I don't have that available in my workplace's ArcGIS subscription, so I need ...
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0answers
9 views

Cannot find Grass7 folder in QGIS 2.18 content folder

I have freshly re-installed QGIS 2.18.28 in the prescribed order. I was under the impression Grass7 in included in one of the install packages. But when trying to point QGIS to the grass7 folder under ...
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1answer
43 views

Raster Volume Returning Wrong Volume

I have a clipped surface using Washington State Plane North (feet) added to a QGIS project using the same CRS. I am trying to calculate the area under this surface (a dirt pile) using SAGA Raster ...
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1answer
38 views

How to split vector layer in PostgreSQL/PostGIS

QGIS has this nice tool to Split a layer into multiple layers based on one attribute and create a new layer for each unique value within that attribute. Is this also possible using PostgreSQL/PostGIS?...
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1answer
27 views

Error after loading new plugin Qgis 3.4

In Qgis 3.4, after creating a plugin with plugin builder, compiling it with pb_tools, I still can't load it to Qgis. I keep getting the following error message: "Couldn't load plugin 'test_api' due ...
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1answer
24 views

Installation of QGIS 3.4.4 on Ubuntu 16.04 fails to install qgis-plugin-grass because of uninstallable grass760 dependency

I have used the instructions here marked Tested 29/06/2018 to install QGIS 3.4.4 on Ubuntu 16.04. While QGIS installs nicely I get an error on installing qgis-plugin-grass. Subsequently the Grass ...
2
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1answer
22 views

Isolating and exporting specific sections of a shapefile in QGIS?

If I have a shapefile layer in QGIS showing the spatial boundaries of subsections of a larger area (e.g. counties within a state, or countries within a continent), how would I selectively crop out one ...
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0answers
24 views

Displaying Legend for Variable Width Line in QGIS

I am using QGIS v3.4 to display a simple line as a line of varying width using the variable line width attribute facility of QGIS (please see screenshot below). The layer displays correctly within ...
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0answers
17 views

QGIS globe map - label distortion [duplicate]

I have created an azimuth orthographic projection map (basically a globe, I've used this custom CRS: +proj=ortho +lat_0=51.470129 +lon_0=-0.452751 +x_0=0 +y_0=0 +a=6371000 +b=6371000 +units=m +no_defs ...
2
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1answer
29 views

QGIS Table Manager

in QGIS 2.18 I used the table manager plugin for renaming or removing columns in a table. This plugin doesn´t exist in QGIS 3.4.1. Is there any other plugin or way to rename,remove or order columns in ...
3
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1answer
33 views

QGIS print composer - Legend columns not aligning when title is deleted

I want a simple legend without a title and with 2 items side by side. I can't find an option to turn the legend off so have just deleted text from the Legend title box. I select Columns (2) - Equal ...
2
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1answer
74 views

Equal values attribute table

I don't know how to filter the attribute table in qgis. I have 2 columns, DN and DN_1, both with values from Corine Land Cover (111,112, 223, etc). I try to select the rows that have the same value. ...
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0answers
22 views

Moving .pdf as a raster freely without referencing

If I import a .pdf as a new raster layer, but the referencing is off. Is there a tool in QGIS to grab and hold on to the pdf so i can move it freely to my desired location without having to worry ...
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0answers
46 views

Reporting distances to polygon features along river network using QGIS?

I am using QGIS 3.6 on windows 10. I am trying to work out a way of reporting on the distances to polygon features (ecological sites) located along a river network. I have extracted the shortest path ...
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0answers
30 views

“slyr-master” plugin for QGIS doesn't work due to “missing meta data”

I downloaded the "slyr" plugin from GitHub which should be able to convert .style data into QGIS. According to the README file, I'm just supposed to add the "slyr" folder to the Python -> Plugin ...
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0answers
30 views

Producing georeferenced raster to open in Google Earth? [on hold]

I'm new to QGIS. How do I georeference a cadastral image from PDF or TIFF, and open it already positioned in Google Earth?
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0answers
37 views

Reprojection puzzle

Initially, my question was about strange results in area calculations in QGIS. I got bigger results for planimetric calculations - using area($geometry) - compared to ellipsoidal calculations - using $...
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0answers
18 views

Error installing visibility analysis plugin

When I try to download and install the latest version of the visibility analysis plugin from both https://plugins.qgis.org/plugins/ViewshedAnalysis/ and http://www.zoran-cuckovic.from.hr/QGIS-...
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2answers
41 views

Selecting highest value within group using QGIS?

I have a .shp of points. This points are organized in groups with same ID (group 1, 2 ,3) Each group has 10 points. Each point has a Z column with Z values. I want to select the point with the ...
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0answers
20 views

QGIS Authentication

I have been doing some reading regarding QGIS authentication. Like most of the threads I have read, I am getting a barrage of authentication requests when someone opens someone else's QGIS project ...
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1answer
27 views

Creating custom CRS from existing CRS EPSG:22780?

I am currently trying to figure out how to create a custom CRS in QGIS based on Deir ez Zor / Levant Stereographic (EPSG:22780). For this I am working with a map which shows both the EPSG:22780 ...
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1answer
39 views

Creating boundaries from points and area measurements

I have a list of villages and the area measurement for each village. Is there a way to draw hypothetical boundaries of each village based on the area measurements and the calculation is able to ...