Questions tagged [qgis]

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

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Automatic layout scope and scale

I have only one shapefile with multiple polygons. Every week I make updates to this shapefile, including new polygons, changing the shape of others and deleting other polygons, that is, this shapefile ...
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58 views

Summing flow from cities listed in another layer within QGIS?

I have transport flow represented by arrows within QGIS in one layer. The database is coded with cities ID for the origin and cities ID for the destination of the flow. I also have in another layer, ...
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51 views

v.net.allpairs - Missing parameter value: WHERE condition SQL statement without where keyword

v.net.allpairs is not running in QGIS 2.18.27 (but runs in QGIS 2.14). QGIS 2.18.27 has responded: Missing parameter value: WHERE condition SQL statement without where keyword. How to fix that?
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95 views

Matching streets in two line datasets with PostGIS or QGIS?

Explanation: I have 2 tables on PostgreSQL, one table named 'city' that have linestrings wich represents streets from a city (using QGIS I downloaded OpenStreetMaps data and imported to PostgreSQL ...
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42 views

Using File Projection in QGIS?

I am using QGIS AND struggling with setting projections. I am attempting to reproject all of my files that I am accumulating into NAD83-UTMzone13 utilizing the reprojection tool. The tool appears to ...
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79 views

QGIS Atlas - Making legend and size assistant automatically update based on which area selected

I'm hoping to use the atlas feature to generate a batch of maps for London postcode districts which will show supply of private indicated by size of dots within the PCD. I was wondering if it was ...
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84 views

ntv2 datum transformations-problem on file output

I am working with qgis 2.18.27 I have installed ntv2 datum transformations and it worked fine, but yesterday it didn't work and i am not finding the way to resolve the issue (explained below) I am ...
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66 views

Filtering trees with Mac

I own about 200 acres of forest with about 350' of elevation change. I have a DJI 4 Advanced and my goal is to produce elevation maps to plan the building of one or more ponds. I've tried and failed,...
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112 views

Download OSM data with QuickOSM and QGIS Modeler example and/or tutorial to share

I would like to automatically search and save my results (11 layers) via the QuickOSM plugin using the Qgis Graphical Modeler. Could anyone help me with some already prepared example or some tutorial ...
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28 views

Altered values of GeoTIFF after vector extraction.QGIS

I've downloaded a LAI (Leaf Area Index) in GeoTIFF format from https://land.copernicus.eu. After I extract some specific area via raster-extraction-extract by mask the raster values are altered. ...
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31 views

field information lost when importing geojson file into qgis

I have an attribute in the geojson file which contains a list of elements (usually 3). The attribute has 700-1000 characters. I learned that for shape files, qgis can only have fields with less than ...
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213 views

Exporting a grid to KMZ with legend (QGIS 3)

I am stuck trying to export a grid with values to a KMZ file with a legend that can be viewed in Google Earth Pro. This is the grid I'm trying to export (it is in EPSG 32756) This is how I need the ...
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39 views

QGIS plugin - Works on PC, not on Mac

I'm adding some functionality to an existing QGIS plugin (EcoValuator from Key-Log Economics). After playing with the existing version of the plugin, it works on a PC, but not on a Mac. The issue is ...
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237 views

Export vector layer with labels to Google Earth as kmz

I have a vector file with contours which i am interested to export it as kmz to google earth with labels similar to the ones QGIS labeling function produces. However I read that Google earth does not ...
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279 views

Lines to polygons error in QGIS

I was using lines to polygons tool and I encountered the following error: "One or more line ignored due to geometry not having a minimum of three vertices." I'm really confused because it worked ...
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191 views

QGIS 3.4.3 - Input dialog for a column in attribute table

I’m working with QGIS 3.4.3 and Python and I’m looking for a better mechanism in attribute table (vector layer) which tells me which fid and which index of a column I’m currently working with. For ...
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93 views

Geoserver+GDAL+OSGEO4W ECW support

I am trying to install the GDAL plugin for Geoserver on machines which have windows 7 and 10. both machines had a previously installed version of OSGeo4W. I followed all the instructions in the ...
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43 views

How can I change the elevation of a lake on a DEM so I show the lake bottom contours?

I'm studying the drainage of a lake and I have a DEM of the lake and the surrounding area. I already identified the shorelines of ancient lake levels at higher elevations, but I would like to keep ...
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44 views

Erroneous contour polygons in QGIS 3

I have a global DEM and try to calculate contour polygons for 4 different heights in QGIS. In the first image below, you can see the colored DEM (white = lowest; yellow = higher; orange = highest) as ...
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50 views

Can't open WMS that worked before

I've been trying to access a several WMS servers in order to visualize imagery on my QGIS but when I put the URL on the searcher no results are given, as if there were no WMS server with such URL . I'...
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59 views

Using a spatial query to filter the atlas pages in QGIS

I would need to create an atlas of all the map sheets (red rectangles) that refer to a specific municipal territory (for example the selected yellow polygon) as in the image. The atlas coverage layer ...
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54 views

Is it possible to do a visibility analysis and create a 3d - cone as a result in ArcGIS?

I have a digital surface model of a region and the coordinates and height of an observer point and need to do a 3d - visibility analysis for this point. However, as a result I would need a ...
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1answer
168 views

Calculating area in the attribute field of a QGIS 3.4.3 project with multiple CRS

The area calculations in my project derived from the attribute field show values way below actual area, because the attribute field assumes the project CRS (EPSG:3857). However, this CRS should remain ...
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209 views

QGIS 3.4, Saved project does not load layers

With QGIS 3.4 I have created a map with OSM data and installed different styles. I saved and closed the project. A few days later, I wanted to continue working on the project. It is shown to me under "...
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1answer
296 views

Join CSV data to a raster file in QGIS

I am trying to join three data files to a raster grid: I have environmental data in the centre of each grid cell (delimited text layer), Sightings (delimited text layer), effort points (delimited ...
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1answer
108 views

How to Classify With Multiple Ancillary Datasets using QGIS?

I've tried using the classifiers in ArcMap which only supports one ancillary dataset and I tried using Orfeo in QGIS 2.18, though the Orfeo Image Classification tool does not accept any ancillary ...
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190 views

Problems with SAGA on QGIS

I'm trying to perform an interpolation on SAGA in QGIS but every time I ran the tool (or any other SAGA tool for that matter) I got the following message: "The following layers were not correctly ...
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50 views

QGIS print composer does not export high res details from Spatialite layer

I downloaded OSM.pbf data from Geofabrik, and I followed https://anitagraser.com/2014/05/31/a-guide-to-googlemaps-like-maps-with-osm-in-qgis/ this example to import pbf file to SpatiaLite layer for ...
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33 views

Move shapefile upper and lower corner points

I have a shapefile that has been generated by an internal tool and had missing shx and dbf files but I was able to generate it using the post in the below link: http://geospatialpython.com/2011/11/...
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122 views

Error during load osm pbf file from QGIS

I was trying to print out Stamen map (Quickmap plugin) in very high quality. However, I was unable to do so, printed out results looks like chequer board or empty. So, I was following the ...
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1answer
33 views

Two different layers of the same area have to be united to form a single layer

I have two different layers containing different polygons and I need to combine them to see the differences over time. So the output has to be a layer containing the attribute of interest of layer ...
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58 views

Sum a Value Relation field in field calculator

I have a polygon layer with a Value Relation field that I'm using to capture upstream catchment areas that contribute to the selected record. An example would be if I had 3 polygons of 100m2 - so I ...
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44 views

Smoothing/denoising DEM to prep for 3D printing?

My DEM was generated from contour lines (as well as break lines and point height data), and the contours persist in the DEM despite doing some basic denoising (although i may not have used the optimal ...
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93 views

Filling Polygon with SVG File so it Will Appear Only One Time in QGIS 3.4.2

I have a layer that shows the world, without Antarctica and small islands. This layer is made of five different polygons. I want to fill it with an SVG file that is displayed non uniform background. ...
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196 views

How do you change the value of a Boolean column in a QGIS 3 Attribute Table?

I am editing feature in a PostgreSQL table in QGIS 3 and while I can edit the values in most columns, I cannot edit the Boolean value. I can enter the cell in edit mode, but keystrokes don't work. I'...
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78 views

Allow access to PostgreSQL database only through QGIS plugin

I created a Python plugin in QGIS that manage the connection to my PostgreSQL database and loading layers in a specific structure, I've created also some personalized widgets to edit attribute tables ...
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141 views

Loading Landsat 8 tiles into QGIS?

I have 65 Landsat 8 tiles I download off of EarthViewer form the USGS website. What is the fastest way I can load these files into QGIS? My issue is that each tile I downloaded came with a folder ...
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35 views

Geocoding large amount of postcodes crashing in MMQGIS

I have 14,000 observations I am geocoding to postcodes around London and surrounding areas. I have 2 files - London postcodes and Britain postcodes. Around 2,000 postcodes fall outside of London so ...
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227 views

Distance calculation with v.net.path in QGIS 3.2

I have 3 layers: origin and destination point shapefiles and network line shapefiles. I want to calculate the shortest path on the network between the origin (250 features) and destinations (20 ...
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175 views

Using QGIS raster calculator for expression of height with RGB?

I'm using QGIS 3.4.1, and downloaded the SRTM TIFF data for the area of my interest, and added the TIFF format SRTM file to my project as a raster layer. Here, I wish to make my own color gradient ...
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178 views

Choosing a Projected CRS in Order of Making a 3D Polygon Display in QGIS 3.4.1

I have been followed the Instructions explained how to make 3D polygons. I have downloaded some random polygons from OSM and defined the 'Extrusion' with the expression rand (5, 40). Then, I ...
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61 views

Reset Postgres connection for loaded layers without restarting QGIS?

I'm working on my QGIS plugin meanwhile I'm commuting to and back from work every day. My mobile hotspot works rather good in general, but the second I lose a stable connection to PostgreSQL server I ...
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50 views

Why is my area offset using the V.buffer tool

I am using QGIS V 3.2, and I am trying to use the v.buffer GRASS TOOL to create a 500 meters exclusion zone (Circle) around a point. After creating a point shapefile I then ran the v.buffer tool and ...
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432 views

QGIS 3.4 - create mbtiles from QGIS server

We are trying to develop a workflow to generate .mbtiles (for offline tiled map viewing) from a QGIS project. A few years back, in QGIS 2.4, we went with QGIS -> multiple tiffs -> multiple GeoTIFFs ->...
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1answer
413 views

Edit a view of a PostGIS table in QGIS

I have a simple layer in PostGIS created as follows: CREATE TABLE layer ( id serial PRIMARY KEY, geom geometry(LINESTRING, 31370), ... ) To avoid duplicate information, I created a view ...
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1answer
134 views

QGIS GDAL Installation Error

I am using a Mac OS High Sierra, version 10.13.6. While installing the more recent version of QGIS, I ran into a popup that said "Failure, The GDAL 2.3 framework is required." Naturally, I opened ...
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50 views

Composer map needs to reset extents each time

I have several maps that are regularly updated and am now having a problem that has only recently begun - each time I reopen a composer to re-PDF my maps, I have to reset the map extents. All of my ...
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1answer
105 views

EU DEM in GRS80 EVRS2000 with geoid EGG08 --> Make it comparable to Black Sea 1975 for Romania

I got contour lines for western Romania in vertical system Black Sea 1975 which is based on elevation data with 100 m resolution. Now I would like to compare that to the EU DEM with higher resolution. ...
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1answer
172 views

QGIS does not export heatmap SLD-files

At the moment I am creating a webmap with PostGIS and GeoServer. I want to style the data using SLD-files, because my data keeps updating. I have made SLD-files for Points and Polygons and that ...
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111 views

QGIS Distance Matrix Output is always consists of zeros?

I have a shapefile with 35 points and I try to have the distance matrix showing the distance of each pixel with each other. I choose the input and the target file the same and the unique ID fields are ...

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