10
votes
Doing heatmap from line data in QGIS?
Since QGIS 3.12 there is an algorithm called Line Density listed in the interpolation algorithm group in the Processing Toolbox (accessible via Processing -> Toolbox).
It is a direct port of the ...
- 211
7
votes
Accepted
What does "layer units" mean?
The documentation says
Radius: Is used to specify the heatmap search radius (or kernel
bandwidth) in meters or map units. The radius specifies the distance
around a point at which the influence ...
- 43.1k
7
votes
Doing heatmap from line data in QGIS?
In fact, it is possible to do line density in QGIS using the standard menus sending parameters to the GDAL executables.
Using gdal_rasterize using the -burn -add switch would create a raster of ...
- 447
7
votes
Doing heatmap from line data in QGIS?
Using a similar approach to the answer from @DPSSpatial, I would use the QChainage plugin to create evenly spaced points along each line.
This plugin generates points along the line, but it doesn't ...
- 20.6k
7
votes
Doing heatmap from line data in QGIS?
I can't find a way to do this in QGIS via the DB Manager / SQLite functions, but in PostGIS, we do the following:
select
(ST_DumpPoints(l.geom)).geom
from linedata as l
This, exported to a new table,...
- 18.9k
7
votes
Uncertainty of a line between two coordinates with uncertainties in QGIS
That was a fun problem! I solved it using QGIS 2.18 but I don't think the tools have drastically changed in 3.0.
1. Generate the lines
I won't give much details here since you already have the lines ...
- 5,719
7
votes
Population density: 1000 people/ km2
Population density is simply calculated by:
Number of People / Land Area
Therefore, 1000 people/km2 is the population density in your case.
Often, population density is measured in km^2 or mi^2 as ...
- 51.8k
6
votes
Accepted
Build Density Map for large dataset
I did a bit of testing and came up with the following solution based on this blog post from Vipin Raj. I think this is the best answer until now, as everything is done on the postgis server.
CREATE ...
- 493
6
votes
Calculating Line Density in QGIS?
Since the release of QGIS 3.12 you can use the native Line Density algorithm from the processing toolbox. It is implemented in C++ and is a 1:1 port of the Line Density tool that is available in the ...
- 2,385
5
votes
Creating population dot density map at the block group level in QGIS
Use Vector -> Research Tools -> Random Points Inside Polygons.
Select the variable, which contains the number of people in each Block (=polygon) under expression. leave sampling strategy ...
- 7,235
5
votes
Accepted
QGIS town label density
I'd be curious to see the data you got, in which you claim there are not fields useful for filtering out smaller localities. QuickOSM will pull in the place and population tags for populated places.
...
- 3,910
4
votes
Accepted
Calculating density map of cycleways using fishnet in ArcGIS Desktop?
To do this I would:
Intersect your cycleways and the fishnet
Use Summary Statistics to SUM the lengths of the intersected cycleways by fishnet polygon ID
Use Join Field to join the summed lengths ...
- 65.4k
4
votes
Accepted
Centroids highest density areas
First you need to convert your Raster to Polygon. Then You can use Eliminate and\or minimum bounding geometry to clean up your polygons. Select your red polygons in any way you wish and run Feature to ...
- 421
4
votes
Accepted
Creating population dot density map at the block group level in QGIS
Unfortunately, you can't set dot density style in QGIS (for now, I hope) as easily as you can do in ArcGIS. You can do it by creating a new Point layer. Do not expect any hope from style window.
You ...
- 78k
4
votes
Producing density map in QGIS
You want the "Graduated" symbology option.
Just choose the column the has the values and choose 4 classes.
- 16.9k
4
votes
Choosing kernel density radius
These are complicated questions, and yes, it does depend on your data but also on your hypothesis. For example you may have an explicit hypothesis regarding boat activity, requiring a set of sigma (...
- 32k
4
votes
Heat Map - Cover non-point areas QGIS
Use the Heatmap renderer for your point-layer: it will cover the whole map canvas.
If you want to cover everything outside of a certain polygon area (city), render this polygon with Inverted Polygon ...
- 74.9k
4
votes
Accepted
Create density map with grid
From this point it is not clear what you would like to have as map in the end. If you need a vector file, do the following in QGIS:
search for "create grid" in the toolbox and create the ...
- 138
4
votes
Accepted
Create density polygons from spatial points in R
Starting with random points as a spatial data frame:
points <- st_sample(polygon, size=50)
st_crs(points) <- "+proj=longlat +ellps=WGS84 +datum=WGS84" #change to lon/lat
get the X-Y ...
- 66.5k
4
votes
Calculating point density as attribute in point layer in QGIS
The best one-step method I can think of is using the Field Calculator to directly create a new attribute with this expression:
array_length(
overlay_nearest(
@layer,
$id,
...
- 74.9k
4
votes
Calculating point density as attribute in point layer in QGIS
There is a possibility of using a "Virtual Layer" through Layer > Add Layer > Add/Edit Virtual Layer....
Let's assume there is a point layer called 'points_in_polygon', see the image ...
- 34k
4
votes
Accepted
Find location of highest point density in QGIS?
Heatmap. Set a search radius, output raster size and kernel_shape=Uniform (Advanced options)
Raster pixels to points to create a point in each raster cell center with the column VALUE storing the cell ...
- 77.8k
3
votes
Getting quantity of intersecting lines of polygons in QGIS?
I tried to also use the refFunctions, in particular the intersecting_geom_count function but I think this only applies if the geometry from both the target and the source are the same. But we can ...
- 76.3k
3
votes
Accepted
How to create a population density heatmap from attributes
In QGIS, you may try to follow these steps:
Right-click on the layer loaded in the Layers Panel;
Go to Properties >> Style;
Choose Heatmap;
Define the field to use for the heatmap (and the ...
- 16.3k
3
votes
Accepted
Calculate Density in QGIS
Your approach have some problems. Creating a grid for calculating density could be wrong, because the dimension (and position) of the grid changes the density (if a group o buildings falls inside two ...
- 1,097
3
votes
Identifying true curves/arcs in ArcMap?
Building on @KHibma's answer, the data access cursor has the token SHAPE@JSON which can be used to check for curves without importing the json module.
with arcpy.da.SearchCursor ("InputFeatures", ["...
- 13.9k
3
votes
How to reduce points by proximity
In the top toolbar: Vector > Shape Tools > Geodesic Geometry Simplification > Geodesic point decimate. You can then specify the input layer, specify the minimum distance between points, and ...
- 51
3
votes
Density map of pedestrian paths and footways in QGIS
Here my workaround:
1) Create an intersect of your lines layer (path/footways) and your polygon layer (grid or areas, e.g. neighborhoods) where you want to represent the density. Your polygons, areas,...
- 356
3
votes
Population density: 1000 people/ km2
They calculate the population density by dividing the number of people by the area of land in square kilometer. If you want to get in people/m2, then you have to divide the result by 1.000.000.
1.000 ...
- 78k
3
votes
Line density for multiple commuters in QGIS
You could try to create a 10m Buffer around your line segments. With the respective geometry operation you should be able to then give the buffer a value according to how many lines overlap with the ...
- 1,639
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