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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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Georeference System Conversion

Please suggest me the appropriate Georeference system for QGIS 3.4 (MAC OS) for the following GPS User Grid System conversion: M E Indian Bangladesh 037 +8.606550e+02 +2.836137e-05 +289 +734 +257 ...
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How to read slope from HYDRO1k database for Asia

The Hydro1k database for Asia is provided by USGS. It is available here as GTOPO30 HYDRO 1K. I tried to read the slope values for the Kumamoto area in Japan but the results all came out as 55537(same ...
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1answer
40 views

I can't find CRS EPSG 27700 in version 3.6.0

I have tried to use the filter element in the Project properties menu to find EPSG 27700 with no success. Any suggestions please for converting to British National Grid
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1answer
42 views

Find percentile values in raster

I have a raster (geotiff) and I would like simply to know some parcentile values, specifically the 80th, 85th, 90th and 95th, because I need to highlight all values above these thresholds in QGIS. ...
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1answer
38 views

How can I download OSM maps at fixed scale? [closed]

Is it not possible to download my area of interest (AoI) in my required scale? I would like to download the AoI in tiles with my specified scale ( SVG or Vector PDF Format).and then stitch all the ...
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1answer
62 views

How to have a window popup as a toolbar on the right side (with fixed size) by default in QGIS?

I have created a plugin which first shows login window and then user needs to enter details and press submit. After details are verified at back-end, a new window appears with buttons for different ...
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36 views

QGIS - 3D data set with stacked points at different elevations, is it possible to create data points at each elevation

I have a 3D dataset consisting of xyz and property. The data points are along vertical axis (boreholes), and at different XY locations (at other borehole location). The data points are not all at the ...
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44 views

Enabling editing for QGIS query layer?

I have a large Postgres/PostGIS database table with ~100 million points that I need to have available for editing (mainly, removing points). Currently, I'm trying to use a QueryLayer in QGIS using ...
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1answer
22 views

QGIS 3.4 crashing when loading two different files with different coordinate systems

I'm having trouble loading some files in QGIS 3.45 "Madiera". I have a CSV loading as WGS84, and a BMP loading in as UTM 12N NAD 83. Both the files load fine individually but as soon as they are ...
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0answers
32 views

Why does QGIS not display an attribute table in the order of its defined schema? [duplicate]

I saw this is a known issue in QGIS v3.2 Bonn. I installed QGIS v3.6 Noosa and still have the same issue. For example) csv of .dbf with expected order: view of attribute table in QGIS: Any ideas?
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29 views

Converting QGIS2 Plugins to QGIS3

I am trying to convert a QGIS2 Plugin to QGIS3; specifically the Quickfinder plugin (I am aware of QGIS3 Locator and no I do not feel it provides the same or similar capability just thought I would ...
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1answer
30 views

QGIS, I uploaded an SVG file as a label. I set the size at 7 however I have two labels appearing massive

Here is a photo below. I am using QGIS 2.18.14 How can I solve this issue and possibly have the labels spread out throughout the rest of the lines and not limited to the ones above?
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1answer
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Get coordinate value displayed at the buttom of qgis window with pyqgis [duplicate]

Does anyone know how I can get the coordinate value displayed at the buttom of the qgis window? I have been searching through the qgis api but am not able to find anything suitable..
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11 views

ROI signature creation error

I'm trying to run a maximum likelihood classification on a Landsat 8 mosaic to assess land cover, but I keep getting the same error during signature generation: I never got this error before, and ...
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1answer
33 views

QGIS plugin: set the position of the featureForm

Im developing QGIS plugin (Python3) to open the featureForm (depending on some of my conditions (matching geometries,...))I use this code: layer = self.iface.activeLayer() ...
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1answer
54 views

Extract the lowest value from an attribute in QGIS

I am not to sure if this is possible? What I am looking to do is. 1 - I have polygon and point data. I want to use the polygon to select the point data that falls within in the radius of the polygon....
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0answers
32 views

Making map from Local Authority data? [duplicate]

I've tried a few things but so far nothing works. I am trying to use ONS data to create a map in QGIS3. Below is an image of the map I have so far. I've used a shapefile to import it into QGIS. Tried ...
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1answer
54 views

From QGIS 3.4.5 and 3.6 asks password repeadly to connect to PostgreSQL 10

Action: At first time when opening project on QGIS 3.4.5 and 3.6 versions needs credentials to connect to PostgreSQL DB. Problem: But after that when connection is success with correct credentials ...
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2answers
46 views

Creating a text report detailing attributes on several GIS layers within a polygon

I am trying to create a text report listed by area (taken from a polygon layer) that details any features from other layers (points, lines and polygons) that fall within the listed area. I have QGIS ...
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0answers
40 views

How to add attribute table into layout pyqgis 3.X

According to the latest official QGIS 3.X API reference there is a class that should insert attribute table of a layer. I tried to do it, but got an error. Here is a piece of code I used: from PyQt5....
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2answers
81 views

Blanking out Wales and Scotland and certain local authorities from map of Local authorities in UK?

I have used a shapefile I've downloaded from ONS for the UK's local authorities. However, I am only interested in certain local authorities in England and want to blank out Scotland and Wales. How ...
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18 views

QLR loaded via PyQGIS not loading correctly but works when using layer--add qlr

Based on Load .qlr with loadNamedStyle I was able to add a QLR to a python tool via PyQGIS -however, it appears broken... elif ftype=='qlr': try: print ...
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1answer
74 views

Label layer as symbol colors with QGIS 3

Is it possible to label a layer using same colors as the categorized symbology of that layer? It is possible using the Rule-based labeling, but it can be difficult for a layer with many categories ...
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28 views

Using QGIS or GRASS API in custom application

I've already read in this link that is not possibile to use QGIS or other GIS application API (GRASS, ArcGIS) without rebuild all libraries into my custom code. First I would like to know if that ...
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1answer
45 views

How to Loading BAG file format in QGIS

I need to load a BAG file (Bathymetry attributed grid) in QGIS (3.4) according to the supported file page https://www.gdal.org/formats_list.html it is supported, but is not compiled by default and ...
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In QGIS, the image in my print manager cannot be saved and only save one layer [closed]

When I try to save an image I made from my print manager in QGIS to my computer, it only seems to save part of it. Eg one layer is saved but another layer from the image isnt. How can this be solved??
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Sentinel 2 imagery does not align with Landsat imagery regardless of coordinate system

I have downloaded Sentinel 2 imagery of Antarctica and imported it into a QGIS project that also contains older Landsat imagery, line vectors, and a basic basemap. The Sentinel 2 imagery was ...
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1answer
52 views

What are pixels? [closed]

Every time I try to use a suitable scale to properly represent a district along with a suitable cartogram on the layout page, either the districts get enormously magnified or the size of the bar ...
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1answer
38 views

Displaying frequently traveled routes? [duplicate]

How can I display frequently traveled routes? I think this has been asked before in a question I am unable to relocate which was about how to display multiple overlapping routes on a map, so that ...
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2answers
48 views

Aggregating census level data to county level in QGIS?

I'm trying to take census tract linked data (in the form of a CSV I joined to a census tract level map of Washington State) and create a county-level map with it. My census data also has the county ...
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0answers
36 views

QGIS Raster Calculator missing bands

I've created a VRT from some 6-band TIFF tiles. The VRT displays perfectly in QGIS 3.6 and I can see manipulate the band arrangement and create different composites. However, when I open the raster ...
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Why does QGIS try to insert a known CRS into sdo_coord_ref_system?

When using "Import vector layer" in QGIS DB Manager (QGIS 3.6.0) to load a layer to an Oracle database (12.2.0.1.0) I get the following error: Error 2 Creation of data source "XXXXX"."MY_TABLE" ...
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1answer
45 views

USA map projection

I know that this issues has been discussed, and I indeed find information on this forum and try the suggestions out. It is about the projection of the USA map shapefile in QGIS. I downloaded the ...
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1answer
24 views

How to set layer transparency QGIS C++ API 2.14?

I want to set transparency for already loaded layer by taking it from canvas QgsVectorLayer *myLayer = mpMapcanvas.layer(0); myLayer.setLayerTransparency(50); myLayer.triggerRepaint(); but get an ...
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0answers
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How is QT designer used to implement radio buttons for a QGIS field

I have a custom data form, created using QT Designer, for interacting with a particular layer on QGIS. A simple line-edit widget on such a form (as with most other form widgets) requires that the ...
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0answers
25 views

Pixel values change when opening in other version

I have a raster layer with pixel values ranging from 0-0.346, which is a result after calculations in QGIS raster calculator (QGIS version 2.18.26). I want to open the same layer in QGIS 3 on another ...
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29 views

Projection of set of point on a line with chainage

I am new to QGIS and in fact new to GIS mapping as whole. I have a line in shp format (which does not have chainage & I want to add chainage added to it). Chainage is the distance from the ...
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1answer
24 views

Filtering attribute table based on names in another table using QGIS?

I have a shapefile showing a list of district names. I have (currently in Excel) a long list of district names in a table. I would like to filter those districts that are in the other list. I think ...
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1answer
20 views

Cost raster/friction map and data extraction

I am in an early stage of least cost paths analysis of a wide area. One part of the operation includes simulation of movement across the grid of previously agreed size of cells and extent of the grid (...
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0answers
31 views

VRT Files from QGIS2+ makes QGIS3 crash when opened

We got a bunch of VRT files that we made using QGIS 2 and which reference a varying number of ECW files (from 8 to 300). Those VRT files were perfectly runing QGIS 2.18. Problem is: Opening those ...
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1answer
64 views

How to have a date earlier than 1753 in QGIS date field?

I'm trying to map out some of my family tree but I've stumbled upon a problem of not being able to put in early dates. I created the shapefile in QGIS and included a date field (dd-mm-yyyy). Whenever ...
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1answer
71 views

Searching oil well SVG-symbols

I’m looking for a set of SVG oil well symbols for QGIS. Black Bart data: http:// blackbartdata . com / QGIS_Petro_SVG_Symbols Just directs me to a spam page. Any other alternatives? This is a ...
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0answers
18 views

Qneat3 / shortest distance calc sensitive to altitude?

I'm trying to calculate shortest distance using Qneat3 (using both the shortest path and OD-matrices for different purposes). And am wondering if there is any possobility to factor in altitide (it is ...
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0answers
70 views

Drawing longest polyline within polygon? [closed]

I am looking for a GIS tool/script (preference on QGIS but I can also use ArcGIS/Matlab) that allows creating a polyline layer from a polygon layer where a polyline is drawn for each polygon. The ...
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0answers
45 views

QGIS Processing Script to Create and Add CSV Layer

I have a QGIS 3 processing script that I'm working on which has the following workflow: Get xy coordinates from a grid layer and construct a list. Make calls to the Google Distance Matrix API using ...
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0answers
30 views

Adding table to layout using PyQGIS [closed]

I need to create a table based on a Python list and paste it in layout view in QGIS. I also found a QgsLayoutTable class in PyQGIS but there's no example of creating a simple table. Does anyone know ...
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0answers
53 views

Increase the size of overlapping lines in QGIS 3.6

In QGIS I have a layer that is a MultiLineString that has many overlapping lines, which represent driving routes around the city which are generated using OSRM. My data looks something like [ [[a,b],...
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1answer
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In QGIS, how can I use a delimited text layer to keep only those polygons and records of a shapefile which match a column in the delimited text layer?

What I want to do is trim the shapefile so that only those records and associated shapes that match the same values in a column in the delimited text layer (which in my case is a CSV) are kept in a ...
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0answers
13 views

ImportPhotos not working for QGIS 2.18.28

I'm trying to geotag and import photos into QGIS (version 2.18.28). I've searched around and tried using ImportPhotos. The photos import successfully and show up on the map but when I click them with "...
2
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1answer
32 views

Select tools with 3D geometry?

I'm trying to work with a layer that uses a PostGIS geometry column of 3D polygons, but hit detection seems to be broken when trying to use the select tools. The geometry renders fine, but when I ...