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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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15 views

NameError: global name 'layer' is not defined

I've modified code of a plugin go2nextfeature as below import os from collections import OrderedDict from geo_utils import utils as geo_utils, vector_utils as vutils from qgis.core import * from ...
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13 views

Printing satellite imagery from ArcGIS Server using QGIS 3

I am using QGIS 3.6.1 I made a map (my first one ever) that includes satellite imagery that I obtained from the ArcGIS Server. The map looks perfect in the Layout, but when I save to a file (PDF, ...
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0answers
101 views

Issues with atlas generator and labelling across maps/images

I have a lot of layers in my project and I am trying to use the atlas generator in the print composer to create a tiled map. Some of the layers have labels which have different configurations with ...
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736 views

Showing features in Layers panel in QGIS? [closed]

I'm new to QGIS. How can I see the features in Layers panel in QGIS in a nested form?
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2answers
92 views

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 ...
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1answer
28 views

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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1answer
17 views

Table Join on distance measures 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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0answers
13 views

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
12 views

Simplify multiple lines: create central axis?

I have a layer with railway lines, downloaded from OpenStreetMap. Every single track is represented separately, so at trainstations, you have several parallel lines, as well as sidelines that lead to ...
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1answer
30 views

Using 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 ...
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2answers
24 views

Getting 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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0answers
15 views

Using list of attributes to create layers?

I have a very long list of values (over 2000 rows) in the following format: 1: TAY100, AB60, EM10 2: CA40, 9, UT26, 24 3: YO56, YE I have a layer with features each with a distinct attribute called ...
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2answers
46 views

Updating two 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
50 views

QGIS Madeira does not connect to WMTS service

Working with a new laptop HP zbook and Windows 10. QGIS Madeira doesn't connect to any WMS service. Error: 2019-03-14T09:57:34 CRITICAL Ongeldige Laag : Raster layer Provider is ongeldig (...
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1answer
237 views

Understanding raster custom transparency options (making null data 100% transparent) in QGIS?

I have a raster with a large null area (see the solid black area in the image below). The "Band 1" value throughout this null area is -3.402823e+38. I'm trying to make sense of the result of my ...
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0answers
32 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
184 views

Vector Fields as Input Variable in Field Calculator

I’m working with QGIS 3.2 Bonn and I try to build a workflow in the graphic modeler. The model aims to build variable buffers depending on values from two attribute fields of an input vector layer. ...
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1answer
79 views

Batch processing ( offset of font marker) in QGIS

I have a group of layers with type linestring. Every line consists of simple line and marker line (font marker). I have a batch file(csv) with offsets of font markers. Do you know if there is any ...
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1answer
21 views

Rasterizing MULTIPLE vector layers in same “grid” so I can do a regression of sorts across pixel units?

For my research, I have collected a bunch of climatic data from my state in vector form. I also have my raster data, which is about 60 points around the state that have a binary assignment of yes/no. ...
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1answer
30 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 ...
2
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2answers
142 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?
3
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1answer
28 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
36 views

Create private access to qgis2web maps on Wordpress site

I want to use Wordpress site and qgis2web plugin to show maps to clients. According to my idea, a user logins to his private page and gets links to his private maps. But when I upload qgis2web folder ...
3
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1answer
33 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
29 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
33 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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1answer
22 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 ...
2
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2answers
77 views

Editing border shape using QGIS?

I add a shapefile of the district in Paris on another shapefile. I would like to match them. See images below: The black border is the original, the blue one is what I want to get. I tried with the ...
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3answers
373 views

Controlling line width when merging vector files into raster?

Using QGIS on Windows 7, I have figured out how to burn a vector file onto a QGIS georeferenced tiff. But the result produces a line only one pixel wide. I am trying to produce a map that can be ...
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1answer
22 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
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 ...
1
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1answer
65 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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2answers
85 views

Automate filling of attribute table using QGIS?

I am new to QGIS and wish to automate my current process. In my project I have to open the attribute table of the batch_16 layer having 5 fields (date, checked_by, td_created, td_catagor and ...
3
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1answer
78 views

Date formating in QGIS using expression?

My expression: day(now()) || '/' || month(now()) || '/' || year(now()) returns current date as 15/4/2019, but I want to get the date in dd/mm/yyyy format i.e. 15/04/2019. How can I get that using ...
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0answers
19 views

Looping group of layers and keeping another layer on in QGIS?

While using loop visible layer plugin, it simply makes a loop of a predefined group of layers, rest of the layers are turned off. What I want is to keep a vector layer on and visible all the time ...
1
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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 ...
6
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1answer
382 views

Display pictures stored as bytea in postgresql column in qgis

does someone knows a possibility to visualize in a bytea column saved photos of a postgresql database in qgis? I would like to store pictures directly into the database, not just the link/ url.
3
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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 ...
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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 ...
2
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0answers
24 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 ...
0
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1answer
218 views

Points data to kml retain color

I have styled my point data with circle and red color symbology. Is there any way to retain the points color when saving layer to kml? Currently when saved and open in google earth, it only shows as a ...
2
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2answers
102 views

QGIS processing scripts - restrict vector input to geometry type

In QGIS processing scripts we define input vector layers by ##inputlayer=vector wich in the gui generates a drop down list from what the user can select one of all available layers. Normaly, ...
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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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2answers
31 views

Reading NV chart data (.bsb and .eap) with QGIS?

I have some data from NV charts. As it looks like the data is contained in .bsb and .eap files. Is there a possibility to implement these data in QGIS as raster as a background? Loading the .bsb data ...
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2answers
280 views

Correlation between raster pixels within each polygon

I have two raster layers with the same extent, CRS, and resolution, and a shapefile consisting of a number of polygons. I would like to calculate the Pearson correlation between the two rasters within ...
1
vote
1answer
28 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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1answer
322 views

Creating a portable map package file folder

I am searching for an expression or some assistance in changing filepaths and links to photos within attributes to relative paths. I have used QConsolidate to create a folder with all the files and ...
2
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2answers
1k views

qgis2web cannot find QtWebKit

I have QGIS 2.18.16, in Arch Linux; I wanted to use the qgis2web plugin and I realized it is not working anymore (it used to work last time I used it a few months back) I get the following error ...
3
votes
2answers
83 views

PyQGIS Raster Band Stats - Access pixel values of raster layer

I am trying to access individual pixel values in a raster layer I'm working with. I can use QgsRasterBandStats to get some information about the raster layer with the following code: layer = iface....
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0answers
22 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 ...