14
votes
Accepted
Inverted filling of polygon in QGIS
I am not sure what was going wrong with inverted polygon style, but here is a simple polygon to show you how to do it:
Go to Layer Properties -> Style -> Change Single Symbol to Inverted ...
- 41.4k
12
votes
Changing feature draw order in QGIS
Just tried to do something like this in Qgis 3.44, as expected the design has changed.
Select Layer, Properties, ->Symbology
On this dialog on the left hand side lurking about the Help and Style ...
- 347
11
votes
Applying HDR (high dynamic range) rendering in QGIS
First of all, what you are trying to achieve is not HDR.
To attain (real) HDR one needs to have excess bit depth, and to discard in a meaningful fashion some bits.
For example, if you have a 3 channel ...
- 6,579
10
votes
Shapefile layers in QGIS don't display unless I zoom out
I had the same problem. In my case, the problematic shapefile had been created by ArcGIS. I fixed it by removing the useless extra files ESRI add to shapefiles (.cpg, .qpj, .sbx, and .shp.xml) ...
- 649
10
votes
Accepted
Contrast enhancement on UInt16 data type to set the maximum value greater than 255 with PyQGIS
Default DataType of QgsContrastEnhancement is Byte (Reference). Specify DataType during instantiation.
Without specifying DataType:
e = QgsContrastEnhancement() # Qgis.Byte by default
e....
- 78k
9
votes
Accepted
Blending DEM hillshade with QMS basemaps
The Multiply blend mode can only darken a layer, not brighten it, so you could only use it for adding shadows from a hillshade layer to a base map, but not the highlights.
I would use the "...
- 6,934
9
votes
Accepted
QGIS low CPU usage why?
A 100% usage display would imply that all CPU cores were being simultaneously fully utilized, no matter how many physical cores the CPU contained (2, 4, 8...). But many software applications are only ...
- 8,356
8
votes
Accepted
How to keep polygons detailed when exporting in QGIS?
Try setting the thickness of the borders of the polygons a bit smaller, in millimeter and maybe change the join style. If you set it too high and on bevel or rounded, the rounded factor you can set in ...
- 7,888
8
votes
Accepted
Labels displaying with multiple bounding rectangles
You're right, it is a debugging setting. It can be handy for troubleshooting labeling issues.
It's next to the pull-down for the labeling list so you may have activated it by mistake. In my version, ...
- 20.6k
8
votes
Accepted
Blending features in QGIS: Approximating road edges for map render
You need to use Symbol levels to have nicely rendered crossing lines. Using symbol levels you can sort the symbol levels and thereby control the order in which the different symbol layers are rendered....
- 41.4k
7
votes
Setting data-driven symbol levels in QGIS
The answer is Yes No.
EDIT
As @Babel pointed it out to me, Symbol levels are a vector layer symbology option to choose the order of symbol layers, see here the official documentation.
So the answer ...
- 15.9k
7
votes
Accepted
In QGIS, how to control the rendering order of objects in a single layer with rule-based symbology?
Go to Symbol Levels, and there choose the order of rendering. Categories with lower number will be rendered first, and thus will show below categories with higher number.
In the above example, drive ...
- 3,211
7
votes
Accepted
Layer not repainting using PyQGIS
I think you are just missing one line needed to create classifications from the color ramp:
ramp_shader.classifyColorRamp()
So, your modified run() method would look like:
def run(self):
# not ...
- 23.1k
6
votes
How to filter features in a layer?
Tested on QGIS 3.10.2-A Coruna
How to apply a filter
* Right-click on the layer listed in panel Layers
* Choose Filter...
* The window Query Builder is displayed
How to build a query in Query ...
- 251
6
votes
Accepted
Wait for canvas to finish rendering before saving image
There are different issues surfacing here
Rendering on screen vs rendering to an image
The signal mapCanvasRefreshed is emitted repeatedly while the canvas is being rendered to screen. For on-screen-...
- 28.1k
6
votes
QGIS 3.0 point cluster renderer, is it possible to control rendering order (z-order)?
It seems as though the point cluster implementation does not allow for this natively.
Consider the point cluster renderer - it essentially analyzes and clusters point data at render time, creating a ...
6
votes
Speed up rendering background vector data in QGIS
You could move the data into PostgreSQL/PostGIS.
This would allow you to make use of spatial indexes on the data and feature simplification in the database.
- 16.9k
6
votes
Accepted
Limit the number of features rendered in a map
QGIS 3.x:
You can use the feature filter in layer properties -> source -> query builder:
E.g. use $id < 51 as expression to only show the first 50 features. Or use "population" &...
- 35.6k
6
votes
Accepted
PyQGIS Legend doesn't update with renderer
You can use the script below (just change your layer name in the first line):
layer_name = 'your_layer_name'
rl = QgsProject.instance().mapLayersByName(layer_name)[0]
prov = rl.dataProvider()
stats = ...
- 23.1k
6
votes
Accepted
Setting symbol rendering based on feature visible length in QGIS
Simply calculate the length on the map canvas using $length / @map_scale and than check if this is longer than the threshold you want: $length / @map_scale > X (don't forget to convert units from ...
- 74.9k
6
votes
Accepted
Set fixed reference scale for QGIS layer with PyQGIS?
You can set a reference scale by getting the renderer of the active layer. You don't need to make a new QgsFeatureRenderer.
lyr = iface.activeLayer()
r = lyr.renderer()
r.setReferenceScale(400_000)
- 78k
5
votes
Accepted
Control custom panes for Leaflet Geojson SVG icons
You just need to specify the pane as an option of your markers (i.e. any individual layer).
L.geoJSON(dots400, {
pointToLayer: function(feature, latlng) {
return L.marker(latlng, {
pane: '...
- 7,253
5
votes
Accepted
If the .osm file encodes all geospatial data, or if Mapnik encodes part of it too
The basic OSM data model (nodes, ways and relations) is described at Elements. The XML format is described at OSM XML, larger extracts usually use PBF instead of XML, PBF has performance advantages (...
- 6,255
5
votes
Accepted
Why QGIS crashes when constructing QgsGraduatedSymbolRenderer object by QgsGraduatedSymbolRenderer.createRenderer() method?
There is no problem in your code or no bug with QGIS. createRenderer method is deprecated since v3.10. Therefore, there may be incompatibility between the method and later versions of QGIS. I ...
- 78k
5
votes
How to speed up the rendering time to display drone-derived orthophoto in QGIS
You need create overviews/pyramids.
You can create them within QGIS in Layer properties / Pyramids. Make sure to use external format to avoid messing up your carefully created, already huge TIFF.
That ...
- 8,406
5
votes
Accepted
Applying HDR (high dynamic range) rendering in QGIS
You can use Orfeo Toolbox, an open source libray specialized in image processing for remote sensing images. It can be used in QGIS - see here how to make it work.
For QGIS versions older than QGIS 3.8,...
- 74.9k
4
votes
Is there a way to render lines with a smooth (bezier) curves in QGIS?
You can use geometry generator to smooth without changing the original data:
- 77.7k
4
votes
Setting data-driven symbol levels in QGIS
Use Control feature rendering order*?
while not at the same technical depth as @J. Monicolo's answer, a workaround (which is not exactly as sporting a full fledge feature-based Symbol levels), is to ...
- 6,579
4
votes
Shapefile layers in QGIS don't display unless I zoom out
I was having the same problem. What solved it for me was using both what RickOrth said and what Vince said.
From the Layer>Properties>General Set the Coordinate reference system from a USER: to the ...
4
votes
Why does rendering from a view take significantly longer than rendering from a table?
I believe that the underlying query (used to make the view) will be executed every time you try to access the view, where if you are just using the source table the select will much simpler.
This ...
- 91
Only top scored, non community-wiki answers of a minimum length are eligible