12
votes
Creating Isochrones in QGIS
Just recently, a new QGIS plugin, called OSM Tools, has been published.
This plugin utilizes OpenRouteService API to compute routes and isochrones for various travel modes such as car, heavy vehicle, ...
- 391
11
votes
Creating Isochrones in QGIS
The plugin QNEAT3 offers a great tool for this creating isochrones or service areas offline based on your own network.
You can run Iso-Areas as polygons or another algorithm:
To get isochrones, ...
- 33k
10
votes
Which tools and methods can be used to create isochrones?
You could have a look at the Targomo API (formerly Route360˚), a pretty simple but powerful JS library which you can use with Leaflet (or even Google maps if you like).
It adds travel time polygons ...
10
votes
Accepted
Average walking distance
The solution: OD Matrix analysis
You can do that with OD Matrix analysis (see here for the concept). This can be done in QGIS using the plugin QNEAT3.
Once installed the plugin, use OD Matrix from ...
- 67.2k
9
votes
PostGIS query for selecting features not connected to rest of road network?
You can easily use PostGIS to select roads that don't intersect any other road:
SELECT id, geom FROM roads a
WHERE NOT EXISTS
(SELECT 1 FROM roads b
WHERE a.id != b.id
AND ...
- 13k
9
votes
Accepted
Is there an optimal algorithm to find the longest shortest path in a network?
I think you may be looking for the Graph Diameter of your network. There are a couple of questions on stackexchange that mention this topic, e.g.:
The time complexity of finding the diameter of a ...
- 2,041
8
votes
Drawing lines between all possible combinations of points using ArcGIS Desktop?
WORKFLOW:
arcpy.SpatialJoin_analysis("points","points", "D:/Scratch/many.shp","JOIN_ONE_TO_MANY","INTERSECT", search_radius="1000000 Meters")
arcpy.SelectLayerByAttribute_management("many", "...
- 22.6k
8
votes
Is there an optimal algorithm to find the longest shortest path in a network?
According to the Wikipedia page Longest path problem, this problem
... is NP-hard, meaning that it cannot be solved in polynomial time
for arbitrary graphs unless P = NP. Stronger hardness ...
- 29.8k
8
votes
Dragging all vertices at a given point programmatically in PyQGIS
This can be done using QGIS tools that you can enable programmatically. That is, there is no need to reinvent the wheel.
Namely, you need to:
Click on the Enable Topological Editing button in the ...
- 36k
8
votes
Accepted
Generating dangle point for polyline in QGIS
Extract the vertices from road layer
Explode the lines
Join each line to the vertices, end points will get line count 1 and all other more than 1
Extract them
- 68.8k
7
votes
Accepted
How to get lines and nodes around the confluence point in a network system (line shapefile)?
You work here with a Graph (Graph Theory) and your confluence point is simply a node with a degree (number of edges adjacent to that node) > 2.
As you mentioned a Python tag, a solution in Python ...
- 54.4k
7
votes
Accepted
Merging close lines using v.clean
Buffering the road may be a solution to this problem.
create a dissolved buffer of the road using around 20 unit map distance.
import the layer into a postgis database and create the middle line ...
- 431
7
votes
Generating dangle point for polyline in QGIS
The specification of any polyline is a little optimistic (given the possibility of duplicate geometries), but for a topologically correct network it can be done using a "Virtual Layer" ...
- 14.7k
7
votes
Automatically extend lines to node in QGIS
Use the following expression with Geoemtry Generator (visualizaiotn only) or Geometry by Expression (for actual geometries) on the line layer. See here for the difference between both options.
Option ...
- 67.2k
6
votes
Creating Isochrones in QGIS
In QGIS 3 a Network analysis toolbox was added:
You can create isochrones based on your network offline by choosing the "Fastest" path type to calculate:
There are fewer settings than in ...
- 33k
6
votes
How to calculate Network Service Areas in QGIS?
QGIS-only answer
QGIS 3 provides out-of-the-box network analysis tools in its Processing toolbox. There are two service area tools: one to compute service areas around a single point and one to ...
- 83.8k
6
votes
How to create an OD road distance matrix in QGIS?
UPDATE - QGIS3:
Since this seems to be an important topic, I would like to share my answer on a similar question.
If you are using the current version of QGIS (3), you can use the plugin QNEAT3. It ...
- 2,375
6
votes
Accepted
How to connect nodes via shortest path along network lines with GRASS v.net modules?
I think I found an answer myself.
The problem seems to be the topology of my network file. If I apply v.clean (snap) followed by v.clean (break or bpol), the nodes can be connected via v.net.steiner ...
- 1,556
6
votes
Shortest path using line layer QGIS
"Shortest path (point to point)" can do what you need. First, all your lines have to be in the same layer. Merge them if needed.
Then, to avoid your error, your lines need to be connected ...
- 33k
6
votes
Selecting certain road length around points in QGIS
This solution relies on two relatively new functions of QGIS expressions: array_sum(), avalilable since QGIS 3.18 and overlay_nearest(), available since QGIS 3.16.
Calculate the total length of the ...
- 67.2k
6
votes
Generating dangle point for polyline in QGIS
To just visualize the dangles, use Geomtetry generator with this expression (see below to create actual geometries):
difference (
collect_geometries (
array_foreach(
array (...
- 67.2k
6
votes
Detecting and making all connected lines in the same direction in QGIS
Compare the azimuth of each line to the line group mean, and reverse the line in each group that deviate the most from the group mean:
Refactor fields (or use two field calculators) to calculate:
...
- 68.8k
6
votes
Calculating distance between two closest points on graph in QGIS
Solution 1: Beeline distance
Use distance matrix tool for a quick and dirty solution: ignoring the network, just beeline distance (for using network, see below). At least from your screenshot, this ...
- 67.2k
5
votes
Creating drive time polygons using Open Source tools?
You might want to check out the open Route360° JavaScript API, which works with both Leaflet and Google maps. It returns travel time polygons for the following travel modes: walk, bike, car, transit.
...
5
votes
Creating network datasets from OSM data in QGIS?
QGIS cannot convert OSM data into a routable graph.
There are other tools which specialize on this task:
osm2pgrouting open source
osm2po free but not open source
Both convert OSM data into a ...
- 83.8k
5
votes
Creating network datasets from OSM data in QGIS?
Assuming you have ArcMap and a Network Analyst extension (as mentioned in your question) it is possible to use OSM data for routing without using qgis. The most important is that you need to generate ...
- 1,938
5
votes
Accepted
ArcGIS Online Network Service
Esri has collected the road datasets from various vendors, but mostly it is HERE (Nokia). For those countries where HERE doesn't have sufficiently good data, local vendor's datasets were obtained (...
- 29.8k
5
votes
Shortest path from points in one layer to points in another layer via roads in QGIS
You'll need some Python scripting because there is currently no GUI solution for this issue.
To get you started, have a look at my point layer to route script for Processing which is based on the ...
- 83.8k
5
votes
Accepted
distance matrix with a linear feature
I did have the same the same research question as you. I wanted to calculate the distance from archaeological sites to rivers. I did have access to a hydrological layer by INEGI. I did have rivers as ...
- 3,002
5
votes
Properter to get travel time as cost for network analysis
Here's a short Properter which I'm working on that might provide part of the answer. It aims to modify shortest path calculations for a road network by excluding freeways (because I'm using it for ...
- 361
Only top scored, non community-wiki answers of a minimum length are eligible